Busting the Myth of the Pre and Post Workout Meal: Fasted Exercise and Its Benefits

I have a Master's degree in physiology, biomechanics and human nutrition. I've spent the past two decades competing in some of the most masochistic events on the planet. From seal fit, Kokoro, Spartan, Agoji, and the world's toughest mudder to 13 Ironman triathlons, brutal bow hunts, adventure races, spearfishing, plant foraging, free diving, bodybuilding and beyond. I combine this intense time in the trenches with a blend of ancestral wisdom and modern science. Search the globe for the world's top experts in performance, fat loss recovery, gut hormones, brain beauty and brawn to deliver you this podcast. Everything you need to know to live an adventurous, joyful and fulfilling life. My name is Ben Greenfield. Enjoy the ride.

Hey, what's up? The episode that you're about to hear is actually taken from a private event that I spoke at on stage in Las Vegas, Nevada recently called Live it to lead it. It was an event for chiropractic docs, physicians, physical therapists, nutritionists, etc. Who wanted to build their business or learn more about some cutting edge health concepts. And a big focus of this particular conference was fasting, the benefits of fasting and the practical ins and outs of fasting. I spoke on something I really haven't spoken on much in the past, but that I have studied up on quite a bit and that would be how to combine fasting with an active lifestyle. How to combine fasting with exercise. So in today's podcast you are getting full access to that talk in which I cover how to actually fast and do exercise, how to fast post workout, how to fast pre workout when not to fast, things that help to support a fast, and the benefits of fasting even when you're active. So hopefully you get a little bit out of today's show. Now this show is actually brought to you by one of the best ways to support fasting and to enhance the benefits of fasting. And that would be the top weight loss and fat burning supplement that I have over at Kion K I O N it's called Kion Lean. Kion Lean is 10% off right now and it is a support for the liver and also support for converting white adipose to brown fat, metabolically active brown fat, and then also controlling your blood sugar levels. It just hits a whole host of parameters that support blood sugar management, weight loss, and again it's called Kion Lean. So you can grab that over at getkeon.com that's getk I-O-N.com very powerful fat loss supplement. I use That a lot before. In particular, something I talk about on today's show, cold thermogenesis. Because when you do that and then you do cryotherapy or you do that and you eat carbs, those would be the two times to use Kion Lean to the best efficacy, you actually get a vastly improved response to carbohydrates and a better conversion of white fat into brown fat. So very cool kind of unique supplement. Kionlean getkion.com Get K O n.k I-O-N.com this podcast is also brought to you by Organifi. If you like to put strange things in powder form into blenders or cups or smoothies and drink those strange things to make your friends jealous of you, that you can drink your salad rather than eating your salad like a cow. You're not a fricking cow. You're not a ruminant, so drink your salad. No, I'm just kidding. Like eat your salad, but also drink all your superfoods in one fell swoop with the best tasting green juice that I think exists. It's got moringa and spirulina and coconut powder, all sorts of minerals in it. It's very, very good stuff. And it tastes. Well, it doesn't taste like ass. Basically, as you would expect, a bunch of greens, you know, the equivalent of like five salads in a can to taste actually tastes pretty, pretty dang good. They do a red juice, they do gold juice. They're probably going to do a purple and a black juice eventually. Maybe a bunch of juices fashioned after the color teams of popular NFL or NBA professional sports organizations. I don't know. But right now they got green, they got gold, they got red. All three are in my pantry. Check them out. It's organifi spelled with an I organifi.com and the discount code that you can use is GREENFIELD. That'll get you 20% off of any of their fine, fine, fair. Organifi. Organifi with an I. Btw, that means by the way. By the way lol. Means laughing out loud, btw. Anyways though, I am actually leading a fasting challenge. A really nifty fasty challenge. Fasty challenge. Nifty fasty. A nifty fasting challenge. It's gonna take place January 5th through January 12th. Sorry, redo that, James. It's going to take place January 7th through January 11th. And what I've compiled is this free how to fasting guide. I'm going to be leading everybody on a five day fast and it's kind of like a version where I've put together different options for people who are familiar with fasting and who want to do this as a water day fast, or a liquid fast, or a very kind of strict fast. I'm including those options. I also have written out options for people who want to do like a modified fast, more of like a fasting mimicking DIET Similar to Dr. Valter Longo's protocol. But basically we are getting as many people together as possible to fast. If you've never fasted before and you want a community, accountability, help, direction, et cetera from me and the team at Kion, then that's an option. And if you just frickin have never fasted before, need your wrap your head around this and you're just, you're scared of fasting and everything that's involved with it, it's perfect for you too. So if you go to the URL for the show notes of this podcast over at BenGreenfieldFitness.com Fasted Exercise, that's BenGreenfieldFitness.com FastedExercise I'll put a link to exactly where you can click to go download the free fasting guide that I've created. It's actually a really good fasting guide even if you don't want to do the fast with everybody from January 7th through 11th. It's a good guide for you. But anyways, you can go download guide for free and join the challenge if you want to join the challenge. So again, it's BenGreenfieldFitness.com Fasted exercise is where you can get all the shownotes and also sign up for the free Fasting Challenge with Keon. I've been thrown to the lions. I feel like having to talk to a bunch of hungry people about how to exercise when you're hungry. So how many of you in here are fasting this morning, by the way? Of course, anyone who doesn't have their hand raised now feels incredibly guilty that they put that they put that stick of butter in their coffee this morning. But ultimately, you know, what Dan has outlined to you is fantastic as far as the actual science of fasting, and I want to get into some of the practical, nitty gritty ways that you can benefit from the combination of exercise and fasting. I actually thought I went a little walk today on the golf course. I like to take take off my shoes and go outside in the sunshine and just get in touch with the planet when I'm traveling. And as I was Walking, I thought, geez, we're so blessed for me to be able to even get up and talk about this. With as many people as are starving around the world, who don't have access to food and who are trying to conserve as much energy as possible by not exercising, we're actually talking about something completely different. We're kind of on a different level and we, we live in this blessed society where we're affluent enough to A, not eat when calories are present and deny that ancestral survival mechanism and then B, not only do that, but then go burn a bunch of calories that normally we'd want to conserve if we were trying to survive for as long as possible. So in a way this is not a super ancestral tactic, exercise while fasting, but in a way it actually is. If you look at some of the, some of the historical examples and current examples of things like persistence, hunting or going for long periods of time without food. When I personally go out on hunts, you know, I forgo the granola bars and the sodium chloride laden prepackaged meals I try to plant, forage or just go hungry. And it's amazing, your sensory perception increases once you cross over into that ketogenic threshold. You're able to go for a longer period of time. You get far more desperate to actually get what you're going after. And it tastes a lot better to cook a backstrap over the fire when you have an eating for two days. But ultimately a lot of this stuff really does spark a little bit of that ancestral mechanism. That's why I think there's so many benefits to what I'm going to share with you today. So I actually got into all of this when I was a bodybuilder, got into this concept of pre and post workout nutrition and how to time it. And of course the prevailing thought pattern in the industry at that point was twofold. A, as soon as you drop the bar, you go stuff face so that you can recover, so that you can hit the magic post workout window, right? The magic post workout window where you have the Jamba Juice vendor right outside the health club and you gotta stop in there and grab your shake. And if you don't miss that magic post workout window, you probably shouldn't have exercised at all because you're not gonna see any benefits. And then of course the other thing was snack and graze, right? So I'd show up to my office each day because at that time I was a personal trainer and I'd have my yogurt and my broccoli and chicken and my energy bar and my other energy bar and my protein shake and my handful of seeds and nuts and raisins. And I would just graze and snack all day long. And really, it wasn't until I got into Ironman triathlon and endurance sports that I began to explore other options. And primarily for me, that was because I was testing my own blood and biomarkers at that point. I was noting issues such as pre type 2 diabetes, rampant insulin levels, rampant glucose levels. My CRP was through the roof. I was healthy on the outside, but I was unhealthy on the inside. And so I remember it was 2013 when I first began to look into this thing called ketosis. And not a lot of people were really talking about ketosis at that point.

There weren't all these fancy keto supplements and keto summits and keto bars and keto oatmeal and keto cookies that taste like cardboard, by the way.

But I wanted to figure out if there was a way that I could do something like an Ironman triathlon and not eat the 400 ish calories of carbohydrates that most of my peers were consuming at the time. So I began to look into. Although things like ketone salts and ketone esters weren't really a thing at that point, or commercially available, I began to look into things like MCT oils or different forms of caprylic acid. I began to look into amino acids. I began to look into electrolytes, a lot of these things that could help to sustain the body during exercise without many carbohydrates on board. And I started to tap into the minds of some of these people who were in the industry at that point. Like I remember when I bonked during Ironman Canada with my first foray into ketosis. I called Dr. Peter Attia, and he exposed me to this idea of taking amino acids so that while you're exercising, you can stave off a blood glucose response, but still not bonk, because the amino acids compete for tryptophan across the blood brain barrier and keep you from getting sleepy during exercise. A lot of people think they run out of carbohydrate during exercise. They actually run out of amino acids. There was this other guy, this shy little researcher in the corner of, I think it was the Ancestral Health Symposium, and nobody knew him, and his name was Dominique d'. Agostino, and he had this little poster presentation of these ketones he was studying up in rats. And now, of course, he's at the forefront of the keto movement. But he kind of turned me onto this idea of using some of these caprylic acids and MCTs and some of these things that were available before the advent of ketones. So that was how I started to get into this idea of some of the things I'm going to talk about in the presentation today, like the myth of pre and post workout nutrition and some of the alternatives to stuffing our face with carbohydrates to support exercise, even long periods of exercise. And when I began to experiment with a lot of these things, a lot of my blood and biomarkers began to normalize.

No more high blood glucose levels, no more high insulin levels, my testosterone went up, my CRP went down. I witnessed a lot of things happen that showed me that these are things that you can do. And as a matter of fact, you can actually gain muscle or maintain muscle if that's your goal when exercising in a fasted state due to some of the growth hormone responses that I'm going to tell you about today.

Now, now, just a little bit about me. I live at home in Washington state with my wife and twin boys. My wife does a lot of cooking demos and ancestral food preparation. I like to tell people I spend my life with one foot in the realm of ancestral science and one foot in the realm of modern biohacking. I'm not close to the idea of a lot of these supplements like ketone salts and ketone esters, a lot of these biohacks out there like photobiomodulation. But I really like to look to what our ancestors would have done as well and try to combine both of those, those things. In my practice and in the supplements that I formulate for my company, Kion, and the work that I do, I like to encourage people to forego all these crazy supplements and biohacks and everything until they are earthing and grounding, getting a lot of mineral rich water that's pure and getting out in the sunlight. If you can start with those three things, then just about every other concept is just the icing on the cake. So it's earthing, grounding, getting outside, mineral rich water and sunlight. Start there. If there's anywhere that you can start to start to optimize your health, that's the key. So Kion, I mentioned, it's just a company that I run where I formulate supplements. And if you want to learn more about that, you can go to getkion.com, getk I-O-N.com and also as I alluded to on the opening for this slide. If you go to liveit18bengreenfieldfitness.com liveit18 for those of you propeller hat wearing nerds in the audience who want to take a deeper dive into the research, et cetera, I've got all the research studies and places where you can take a deeper dive there on that page. So let's begin here. Before I jump into 10 of the benefits of fasting the myth that you need to snack throughout the day and eat a pre and post workout meal. Now this of course was the prevailing opinion for a very long period of time. But when you look at a lot of these studies that are telling you that you need to drop everything to go have your maltodextrin fructose whey protein shake within 20 minutes after you finished your workout, there are specific things at play in a lot of these studies that people aren't aware of. For example, the studies that show this to be beneficial show it only to be beneficial for maintaining anabolism after an 8 to 12 hour overnight fast. Meaning that the only reason that you would benefit from eating after a workout would be if you say wake up after an overnight fast and you haven't eaten for eight to 12 hours, you've worked out that would be the time where eating could be beneficial from a hormonal from a post workout protein synthesis standpoint. But it's very seldom that a lot of people, especially in the fitness industry, are getting up, fasted in the morning, working out and then moving on to their meal. Usually there's a pre workout supplement, usually there's a breakfast, usually there's fats in the coffee. All of those things would blunt a lot of the benefits that I'm going to show you later on. But that's one thing is that a lot of these studies that showed the benefit of post workout nutrition, they were done in people who were working out after an 8 to 12 hour overnight fast and then eating. So lesson number one is that post workout nutrition important vastly decreases if you haven't been fasting leading into the workout. Meaning if you're working out at 4pm and you had lunch at noon, or you're working out at 10am and you had breakfast at 8am the other thing that these studies show is that the only benefit that you get from a performance standpoint to eating after a workout would be if you are going to workout again within eight hours. How many of you have children who compete in sports or maybe like weekend volleyball tournaments or Tennis tournaments, water polo matches, any of these kind of events where, you know, like a child for example, and in many cases a professional athlete has two a days, three a days, multiple competitions during a tournament, et cetera. In those situations, post workout nutrition and eating becomes paramount. Hitting that post workout window and preferably getting it as close to 20 minutes becomes paramount. Because if you are exercising again within eight hours after the workout or the exercise or the competition that you've just done, then that becomes necessary to actually eat that much to refill those stores and get the hormonal response and the recovery response to eating post exercise. Now, if you simply eat ad libitum according to appetite, following a basic meal plan, or even following this one a day meal plan, doesn't matter. What happens is after 24 hours, the body naturally restores all of its glycogen levels and it's just fine for the next day's workout. So again, the only two scenarios in which eating after a workout has been shown to be beneficial would be a, if you've been fasting for 8 to 12 hours and then you work out, eating a post workout meal at that point would be beneficial. And it appears based on literature and women's hormones especially, that that's even more paramount for women. And then the second scenario in which you would want to prioritize eating after workout would be if you are going to workout again within eight hours, or you're a professional athlete in a tournament or doing like a two a day or something like that, those are really the only two scenarios. Everything else, when it comes to this pre and post workout nutrition, there's no reason to do it. And especially when it comes to pre workout nutrition, if you've eaten prior to a workout, like if, let's say you've had breakfast at 7 and you're working out at 9, or you've had lunch at 1 and you're working out at 4, your blood levels of amino acids, your glycogen availability and all the substrates necessary for exercise are still in your bloodstream. I mean, there is no reason to go eat the post workout nutrition bar when you're still burping up your pre workout nutrition bar. And I wish more people in the fitness industry knew this. The only caveat to this is I've worked with a lot of, you know, for example, like high school football players, some athletes who need to put on mass, who need to put on weight.

I break all the rules in that scenario. All the rules? Yes, you can maintain muscle mass and you can build muscle if you're fasting due to the growth hormone response that we'll talk about. But when your number one pure goal is muscle mass, which admittedly flies in the face of longevity. But there are certain people who need to put on muscle for, you know, for making the varsity squad. For example, in those individuals, I have them eating six to eight times per day. And often it's 6,000 to 8,000 calories per day. I mean, it's a lot of food. But that's kind of a very unique scenario. And most people, well, I don't know, I mean, how many of you in here would prioritize health and longevity over muscle mass and peer performance?

Yeah, I used to be someone who wouldn't have had my hand raised. I was just, yeah, I want to get out there and crush it and perform and build as much muscle as possible. And I no longer feel that way. I mean, you just feel so much better when you live in this more natural way rather than just basically operating based on performance and vanity. So what we're going to go over today before we get into the 10 benefits of fasted exercise, is what facet exercise actually is. I mean, when we look at a lot of these studies, you already know what fasted exercise is. So first of all, it would be exercising in a state of glycogen depletion. So after about an 8 to 12 hour overnight fast, your liver is emptied primarily of its glycogen stores. The liver can store about 300 to 400 calories or so of glycogen. So after you fasted overnight, you're going to begin tapping into muscle glycogen. And when that happens, some of these protein repair mechanisms, growth hormone responses and testosterone responses, begin to kick in. Now you still see some of those benefits even if you fasted for four to five hours. So this would be a scenario in which you've had lunch and you're going to go workout before dinner. And this is often my case, this is exactly what I do. So my scenario, my exercise scenario is I begin an intermittent fast of 12 to 16 hours each day. So if I finish dinner, let's say around 8pm, then I won't eat again until at least 8am and I'm typically eating closer to about 10 to 11am at some point during that window of time, I'm doing something easy, like the barefoot walk out in the golf course course that I did this morning, a swim, a sauna session, something like that, like easy fasted exercise in the morning. Primarily because you have a natural cortisol release in the morning, it's not necessarily beneficial to activate your sympathetic nervous system and go to a CrossFit wad or a very difficult workout versus something a little bit easier. You run into things that I'll talk about later like post workout caloric hyper compensation and a little bit more of a temptation to be sedentary. And a lot of these issues we see when you work out hard in the morning. Whereas when you work out easy in the morning and save your hard workout for the afternoon or the early evening when body temperature peaks and grip strength peaks and post workout protein synthesis peaks and all these things happen that make a hard workout later on in the afternoon better. It's a very beautiful scenario. Easy something in the morning, hard something in the evening. And this doesn't count as a scenario that would fit into that like two a day scenario where you'd want to prioritize eating right after that morning fasted exercise because you're going to be working out hard again within eight hours. I don't count that morning fasted easy exercise session as a formal exercise session per se as much as just moving. So the idea is that this means that if you're going to exercise hard in the afternoon or the early evening, you would not eat prior to that exercise session. So you would be fasted from lunch all the way up to a hard workout session in the afternoon or the early evening. And in an ideal scenario you would also be fasted overnight and then you would do something easy in the morning. Now there are a lot of different ways that you can kind of work around that scenario. If you're somebody who can only work out in the morning, then you just fast overnight and then work out in the morning. But the idea is you're fasted for about 8 to 12 hours and then you do eat after the actual workout, but it doesn't need to be immediately after the workout. And there are some benefits of especially if you are. If you've eaten within the past several hours and it's not that overnight fast. There are some benefits to actually waiting for one to two hours until insulin has subsided from that workout that you've done for you to eat again. I'll get into some of that in a second. But ultimately that's my scenario is an 8 to 12 hour overnight fast and then usually something done in the later afternoon or the early evening when the body is very primed for hard exercise. And in that scenario I've still fasted since lunch, with lunch usually being about 1 or 2pm well, hello. I want to interrupt today's show to talk to you about manscaping. No, I'm not shaving. I have a lot of friends who manscape and it's not something so I manscape, but not as often as some of these cats. 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Let's go ahead and go over these 10 benefits of fasted exercise. So the first is burning more fat. And a lot of these are going to be pretty intuitive for you based on Dan's presentation. What they found is that for 24 hours, for 24 hours following a fasted morning exercise session, and in this case it was a fasted aerobic morning exercise session. Meaning we're only talking like 30 to 45 minutes of hiking or walking or swimming or yoga or even like you know, sauna to the cold pool, anything like that that gets the blood flowing. We see increased fat oxidation rates for 24 hours following that type of fasted workout. And in this case this was fasted in the morning before breakfast. There's actually a great book called Change youe Schedule, Change youe Life. It's kind of like an ayurvedic medicine book. And it goes into this idea of some of the most important things that you can do would be to do some type of movement in the morning before breakfast and then to have your biggest meal of the day be lunch. And then the final one was to just basically be outdoors as much as possible and get exposure to sunlight during the day. But ultimately this idea of increased beta oxidation, increased fat oxidation for 24 hours post exercise is one of the benefits that we see if the exercise is done in the morning before breakfast. And again, it can be easy. This does not have to be like a soul crushing hard workout. The Next benefit is an anti aging effect. Now, one of the reasons for this is because two of the things that are responsible for shutting down some of the oxidation pathways related to aging are glutathione and superoxide dismutase. We see an increase in both of these antioxidants when exercise is done in a fasted state. Again, this is that scenario where there's an overnight fast of 8 to 12 hours, then an exercise session, and after that you can still eat. But the important thing is that the exercise session be done in a fasted state after eight to 12 hours to get that up. Regulation of some of these antioxidant pathways that have a direct anti aging effect. Now, Dan alluded to some of the stem cell benefits of fasting as well. And of course, that's also a key benefit is the upregulation of this stem cell production or stem cell proliferation. So the anti aging effect is another one. Better brain function. There's two different proteins, one that you're probably familiar with. Bdnf, Brain derived neurotrophic factor. This one goes way up when you do a facet exercise session. I mean, it's amplified with aerobic training more than strength training, simply because when you strength train, a little bit more of the BDNF stays at the muscular level, less travels and gets to the brain for the brain effects. But ultimately, both aerobic exercise and to a lesser extent, weight training will increase bdnf. But doing it in a fasted state amplifies the effect even more. This is why, you know, if I have a cognitively demanding day or I have to go talk to a bunch of hungry people at a conference about fasting, I'll go out and do some kind of like easy walk or easy session or easy something in the morning because you get that amplification of bdnf. There are other ways that we could increase bdnf, right? Like examples would be the sauna, right. We know heat exposure increases bdnf. Lion's mane extract is another one. There's a lot of research that's kind of hot on the presses right now about psilocybin and psychedelics for increasing bdnf. A lot of different ways to do it. But aerobic exercise in a fasted state really amplifies bdnf. So that's another one that we see in literature. Increased growth hormone levels. This one I get a lot of questions about. And I didn't even really look into this or realize it. I always thought, and this was still just like leftover relics from my bodybuilding days that you had to eat after a workout to get that anabolic growth hormone testosterone response. But it turns out that one of the key mechanisms for preserving proteins and for enhancing muscle fiber and repair via better protein synthesis is growth hormone. And our bodies have this natural ancestral built in mechanism that when we don't have enough calories on board, but yet we still need to maintain muscle, one of the best ways to do that is to increase growth hormone production and to a lesser extent, when the fasted exercise is done in moderation and not overdone an increase in testosterone as well. Now this would be the case where for example, you've had lunch, you go out and you do a late afternoon or an early evening exercise session and then you wait about one to two hours to eat dinner. And this is my practice most days. Now the reasoning behind waiting about one to two hours to get that growth hormone or eat testosterone response is because the lower the insulin levels are, the better that that's going to happen. When you work out, you get a natural rise in insulin. It takes about one to two hours for that natural rise in insulin to diminish. So when people say, well, how long should I wait after a fasted workout to eat? If you've eaten in the past four to five hours, like you've had lunch and it's an afternoon early evening session, you'd wait about one to two hours. If you've already fasted overnight, you've done an eight to 12 hour overnight fast and you've done like that morning exercise session. You can actually still see a growth hormone response if you have a breakfast right after or in the hour after that morning exercise session. Right. So it kind of depends how long you've been fasting going into the exercise session. But ultimately the growth hormone and the testosterone response are there to actually maintain and preserve muscle. And very similar to how you see an upregulation, I'll talk about this when I talk about the performance effects. Very similar to how you can see an upregulation in in endurance performance. Because the body gets better at sparing glucose, it's sparing glycogen, it up regulates this enzyme called glycogen synthase. When you exercise, the same thing happens with growth hormone and testosterone. You upregulate the sensitivity of the receptors that interact with growth hormone and testosterone. And this is why many of my friends who have done like these 3 and 5 day fasts or fmds similar to Valter Longo's protocol once they start lifting and exercising and eating a little bit more more after they've done that three to five day fast, they note a remarkable increase in muscle mass and muscle gain from doing that. So this is also something you can put at several points throughout the year. These three to five day fasts which when you finish them and you start lifting again, you get an increased growth hormone and testosterone sensitivity, better muscle mass, better muscle maintenance. So it's a very cool trick for growth hormone and testosterone. Improved insulin sensitivity. This one really is kind of a no brainer.

The key though, especially with that afternoon evening exercise, would be to wait until insulin has dropped off a little bit after the workout. So yet again, it's not just fasted exercise, it's waiting after the exercise for one to two hours if you've eaten about four to five hours prior to the workout. For the morning exercise, we still see increased insulin sensitivity even when breakfast is eaten right after the workout, meaning sitting down to a smoothie 20 minutes after your workout, provided that that workout's done after fasting for 8 to 12 hours. So increase in insulin sensitivity is another big one and that doesn't take a lot of people by surprise. Increased testosterone. I talked about this. But the one thing that you need to be careful with, and this is more so especially in lean active women who require testosterone quite significantly, as do men. Of course the issue is that when you overdo fasted exercise or you do extremely good glycogen depleting exercise sessions in a completely fasted, especially an overnight state, you can tend to see a drop in hormone production. Basically it's another one of those ancestral mechanisms where nature doesn't want starved people who are hungry and running from lions to make babies. That's not a very sustainable scenario in which to bring new people into the world to get eaten by the lions and chase and not have food. So we down regulate a lot of these hormones responsible for fertility. So the trick is if you're going to do harder workout sessions and you're going to do those in a fasted state, then ideally you would save them for the afternoon or the early evening. So you haven't been fasting for eight to 12 hours or you do them in the morning, but you do make sure to prioritize a post workout meal. I see over and over again in the people who will do like a hard morning workout but then not eat a drop in those hormones or in the people who just basically are working out too much and not eating enough, you see the same thing but ultimately the scenario here is if you get up in the morning, and this is especially important to tell your female clients or patients or you yourself, if you get up in the morning and your only time to do a hard exercise session is in the morning and you've been fasting for eight to 12 hours, if you are male, you would actually be able to get through that pretty well. But you'd want to prioritize your post workout and nutrition. And in women, I'll even have them do something like a smaller workout snack after they've been fasting. But this would be something that's non insulinogenic. Like you take 20 grams of amino acids or you take a little bit of MCT oil or something like that. That's only if it's going to be a really hard workout though, like an hour long strength training workout, a CrossFit wad, something like that. Not the easy morning movement that I was talking about. But you do see an increase in testosterone when fasted workouts are done in, in moderation. And it's not like a crazy soul crushing workout in which you're starved before and you're starving yourself after. Enhanced fat loss, that's another one that of course is related to the beta oxidation that we see. You see an upregulation.

In adiponectin, a lot of these enzymes responsible for mobilizing fatty acids from fat tissue. Again that one's kind of a no brainer, but it's, it's another thing that we see right off the bat is better fat loss due to directly an increased ability to be able to mobilize fatty acids from adipose tissue. What I like about this is you can amplify this response even more. And this is a little trick if you combine fasted exercise with cold. Because when you already have these enzymes in your system, you can also upregulate the conversion of white fat into metabolically active brown fat. And so a perfect scenario for this would be you wake up overnight in a fasted state. You've been fasting for eight to 12 hours. You do that easy morning exercise session like a walk and then you finish with a five minute cold shower or a quick dip into a cold plunge, or a cryotherapy session, or jumping into an icy river or lake or sea that up regulates that fat enzyme conversion even more. So I really like the scenario of waking up fasted, doing something easy and then finishing with the cold. That's how I help a lot of people lose a lot of weight in a sustainable way without feeling like they have to roll out of bed and do something hard every morning. Typically, it's sustainable for most people to kind of ease themselves into a cold shower after an easy 30 minute walk in the sunshine, and they haven't eaten for eight to 12 hours. It's a very simple, sustainable scenario for a lot of people and it works really well. Better endurance. I alluded to this and that glycogen synthase enzyme, but there's some really fascinating studies that they've done in athletes called train low, race high, or train low, compete high. And what they found is that when you take endurance athletes and have them train in a carbohydrate depleted state, you actually upregulate some of these enzymes, such as glycogen synthase, for example, which is responsible for taking glucose and converting it into storage glycogen, like muscle glycogen in the body. You also see better glucose sparing, better use of fatty acids during exercise, and a lower throughput of glucose or a less steep exhaustion of glycogen stores during exercise. So what this means is that, for example, for an endurance athlete, someone who's going to do a triathlon or a marathon or a swimming race or anything like that, by going through a carbohydrate depletion state or carbohydrate depleted training over and over again. And some of the studies, these were actually studies where they would fast them overnight, they'd go out, do a hard endurance session, come back, and then they'd have their breakfast. Basically that kind of training in a depleted state. In some studies they would train at night, not eat carbs, sleep overnight, then train again. Some of these studies are pretty rigorous. What they found was that once these people got carbohydrates before exercise or during exercise, they used them far more efficiently. So this is something that can be used as almost like a hack to increase endurance as well. The key is that for someone like an Ironman triathlete, and this is what I'll have my athlete do, is they'll follow a relatively ketotic low carbohydrate diet as long as they don't have familial hypercholesteremia or some PPAR gene issue or an inflammatory response to a ketogenic diet, a very small number of people do. But ultimately if they don't fall into that category, I'll keep them relatively ketotic for all the way going into the race until just a few days before the race, and then we'll start to get more sweet potatoes and Yams and white rice and some of these safe starches and healthy carbs, the body soaks that up and the performance goes through the roof. But it requires a carbohydrate depletion phase beforehand. It's very similar to this idea, especially for active people, of doing like a weekly refeed, or in very active people, sometimes a nightly refeed where you actually eat carbohydrates ad libitum, but only at specific portions during the week or at specific stages during the week. And that'll depend on your level of physical activity. Like a lot of lot of folks who just live a, a normal kind of non athletic, sane life, they'll do like a weekly refeed. A lot of the people I work with who are like bodybuilders or pro athletes, they'll literally do like a nightly refeed on carbohydrates, where you have 100 to 200 grams of carbohydrate at night, then you do an intermittent fast. You don't eat carbohydrates all day long, and then you rinse, wash and repeat at the end of the day, again with good, healthy carbohydrates. So that's another very, very cool effect that actually was only elucidated in the past several years. More stable gut during exercise.

Again, like bdnf, there's a lot of ways to stabilize the gut during exercise. You know, I'm a huge fan of, for example, colostrum, I like L glutamine, I like bone broth. You know, there's a lot of things that you can do to coat the lining of the stomach and keep the gut less permeable, especially during exercise. Anytime you exercise, and especially when you exercise in the heat, what happens is you get increased gut permeability. And that can not only lead to passage of undigested food matter and larger proteins from the digestive tract into the bloodstream, but it can also lead to gastric distress. So the idea here is that you can minimize a lot of that by simply not eating before exercise or consuming things that don't need to be digested or are pre digested. This is why I'm a fan of amino acids. This is why I'm a fan of MCT oils, which, which can largely bypass a lot of the digestive process to be converted directly into triglycerides. This is why I'm a fan of electrolytes, which we'll talk about momentarily. But a lot of things that don't need to be digested could be taken prior to a Harder or a longer fasted workout, but anything that requires digestion, protein, carbohydrates, traditional fats, et cetera, you just get a more stable gut during exercise. And you'll find a lot of people simply exercise better when they exercise in a fasted state. Hunger management you definitely see when you have people who are hungry, who have appetite cravings, carbohydrate cravings, et cetera, One of the best ways to actually get rid of those cravings is to go for a walk or go exercise. You actually see a blunting of the hormone ghrelin, you see an increase in the hormone leptin. So the two hormones responsible for stabilizing appetite become more regulated as soon as you start exercising. And I mean, this is something I'll tell a lot of people who get a lot of cravings, I'll tell them, well, a, are you hydrated? Drink water, see if you're still hungry, and B, go for a walk and see if you're still hungry. These are two very potent ways to stabilize the appetite. Again, this is all very simple and straightforward and understandable, but the idea is that it's a very, very potent way to manage hunger as well. Now, of course the only caveat I would put in there is you need to be careful with the post workout caloric hyper compensation, doing the fasted morning workout, slapping yourself on the back that you did it, and then heading to Denny's for the stack of pancakes or making your smoothie twice as big because you exercised in a fasted state. Those are the kind of things that you do need to be careful with. Okay, so how do we actually do it? What are some of the practical ways to do this? The first, and these are going to go pretty quickly because I explained a lot of this to you already.

One is to exercise before breakfast. And I will allow time for questions too when I finish. So if you guys have questions and you want to explore some of this a little bit more, that's fine. But exercising before breakfast. One question I do get is if you exercise before breakfast, does this mean that you need to include carbohydrates with breakfast? This would only be the case where again, you're one of those like pro athletes or the 2 a day people who are going to exercise again within eight hours. In that case, you would include carbohydrates with breakfast. But in most cases you can wait all the way until the end of the day because that end of the day carbohydrate refeed will restore the glycogen levels Restore the carbohydrate levels so that you can get up the next day and work out hard just fine without necessarily eating carbohydrates after breakfast. But one way to do it, the easiest way to do it, I think this is the best way to get people started, is exercise before breakfast. Easy walk in the sunshine, finish with a little bit of cold, and then go have your breakfast. It's a very simple entry level way for people to get into this. I already talked about this. Wait after afternoon or early evening exercise. So what this means is that you have lunch whenever you're gonna have lunch, then you do preferably your harder workout session in the afternoon or the early evening, then you wait one to two hours to eat. So in my personal scenario, we actually wait in our household slightly longer than what I think is healthy to eat dinner. And the reason for that is because I'm a big fan fan of family dinners and our entire family being able to gather at the end of the day and chat about our day and share our gratitude journals and talk about how the kids enjoyed the day at school and just we take out games and cards and table topics cards and we have an amazing family dinner. But the only way that that happens is we have to wait until the kids are done with jiu jitsu and tennis and mom and I are done with all of our tasks and she's done being the chauffeur and I've gotten everything out of the way. And so we often eat dinner at 8 or 8:30pm ideally from a metabolic standpoint and a circadian rhythmicity standpoint. You can read about these kind of concepts in, for example, Dr. Satchin Panda's new book, the Circadian Code.

You should have most of your hard exercise and you should have most of your eating done by about 3 hours prior to bedtime. But I break those rules in our house regarding the dinner simply because for me, the pros of having the family all eat together outweigh any metabolic cons of me going to bed, you know, an hour after dinner. But anyways, the idea is you would wait until the afternoon or the evening to exercise. So I'll have lunch around 1:30, I'll work out around 5 or 6, and then I'll get some work done, play with the kids, et cetera. And we'll usually eat dinner around 8 or 8:30. So that's typically the way that we do it in our house. But there's a few different ways you can skin that cap, but ultimately you wait one to two hours after your afternoon or early evening exercise to eat dinner. The next one is to use supplements. I talked about amino acids already. That's a really good one. Another one, are these ketone salts or ketone esters? Yes, they are almost like, I mean if you look at macronutrients, we talk about carbohydrates, protein and fat, but really there's five, right? There's carbohydrates, protein, fat, alcohol and ketones. They're all burnt in very different ways. So I would classify us as having five different macronutrients. Now ketones do contain some amount of calories, but they can actually amplify some of the anti inflammatory and longevity benefits of fasted exercise. So I'm not opposed to, especially for very active people who aren't necessarily trying to restrict calories as much as get a lot of the benefits of fasting. I'm not opposed to those people actually doing something like ketone salt or ketone esters prior to exercise. I'll do this quite often. The two I'm holding there, essential amino acids and some form of a ketone ester or ketone salt. I find that I can exercise in a fasted state and even do like a harder exercise session in a fasted state. And it's like rocket fuel. Another one. And this is especially important because as the body dumps glycogen, as the body loses storage carbohydrate, you tend to lose minerals along with that. And anyone in a ketotic state also needs higher levels of potassium. And so the use of electrolytes I think is very important as well. And that could be anything from. There's a lot of options out there. Like I have the trace liquid minerals made by aqua. True. I've got a quicksilver scientific hypertonic solution called Quintron which is almost like seawater. I use a lot of Celtic sea salt. I'll use like the noon effervescent electrolyte tablets. But for me, for a lot of those fasted sessions and just on a daily basis, because I stay in a relatively ketogenic state, I find that electrolytes tend to work really well also. And then there are some things that can amplify the benefits of being in a fasted state that can increase fatty acid utilization when you exercise while fasted. We're talking about things like coffee. Green tea is another fantastic one. I get some questions about these so called exercise mimetics like berberine or bitter melon extract fats or metformin like derivatives. I'm not A fan of those. A lot of people have asked me about combining those with exercise. Usually the hypoglycemic response to those is so profound you get dizzy and tired during exercise. So I'm not a fan of those. But some of these other supplements that are relatively low in calories but don't have an insulinogenic response, like amino acids, like ketones, like electrolytes, those are all very useful to have in your pocket especially for harder fasted workouts. Like if you start into this afternoon or early evening or hard workout scenario and you find yourself dizzy or low on energy or just like too hungry afterwards, sometimes just like having lunch and let's say you're going to work out at 5 and just doing a little bit of ketones, a little bit of amino acids before that afternoon or early evening workout, especially if it's going to be harder. That can help out. I find especially for leaner people, that works. Okay, so a few cautions here. One would be bonking and I already alluded to this.

Of course you can, if you're working out for a long period of time, completely run out of liver glycogen and muscle glycogen. And very few people, for example in this crowd that I'm speaking to now are like professional ironman triathletes or professional athletes. Sometimes I'll lecture in front of pro teams and stuff and I have to warn guys, don't overdo this or you're going to run out of glycogen. But I find in many cases in the general population who's well fed and not overly active, a drop in blood levels of amino acids and the subsequent central nervous system fatigue that occurs from when that happens is the number one reason that a bonk happens. And so if you find yourself super hungry during a workout and you're like, man, I ate carbs last night, I'm not too calorically depleted. I'm in this fasted workout and I'm super duper light headed and sluggish. You may want to look into whether or not that's just tryptophan crossing the blood brain barrier and making you excessively sleepy, in which case you can use amino acids to actually stave that off. So that's one thing that you can do. But then if you're very active, you want to be aware that you your carbohydrate needs and the importance of that carbohydrate refeed in the evening, if you're doing a lot of these fasted sessions, becomes very important.

Next is decreased intensity. So here's the deal. They've found that folks who exercise in a fasted state, who are doing low level aerobic endurance or who are doing powerlifting in very quick like 10 to 30 second efforts, they do just fine. And in a ketotic state or a fasted state, there's not that much of a, a loss of performance because the aerobic exercise uses mostly fatty acids as a fuel. And those short 10 to 30 second like hardcore efforts, those primarily use creatine phosphate as a fuel. But then once you start to get into like CrossFit workouts, longer, like two minute row sessions, a lot of these kind of like metabolic interval training sessions, spin classes, things that require you to be at an elevated level of intensity for two minutes or longer, that's where you start to see a decrease intensity. So if I'm working with like a power lifter or someone who's just creating very short bursts of energy that are under 30 seconds, I'm not worried about that person losing intensity in a fasted state. Neither am I worried about an endurance athlete not being able to train aerobically in a fasted state. But people who are doing like two, three, four minute intervals, things that cause the body to actually burn areas where we create a lot of lactic acid, that's where the loss of glycogen and the decreased glycogen availability from, from working out in a fasted state can decrease intensity and decrease performance. So that's a population or workout scenario in which you'd want to be a little bit more careful. So decrease intensity with a caveat. Depends on the actual scenario. Post workout caloric hyper compensation where like face stuffing. Those are the two things I see like people who do a hard workout in the morning because I fall into the same category, right? Like you're tempted to eat more for breakfast. If you don't actually just be mindful and realize that you're going to be hungrier. I mean for me that's part of it is I just tell myself when I finish anything that's hard, including that afternoon or early evening hard workout, hey, you're going to be hungry and that's okay. You're going to have a little bit of a growth hormone and a testosterone response. The pros outweigh the cons. But that's one thing is post workout caloric hyper compensation then also just sedentary, right? You worked out hard in the morning, so you justify sitting for two or three hours during the day at work because your legs are sore. From the squats or whatever. But those are two things to be cautious with. And post workout caloric hyper compensation is just something to keep an eye on in people who are doing fasted workouts. Because I tend to see that pop up over and over again. By the end of the day they've eaten more calories than they normally would have. And granted, Dan made a good point. Like part of the magic of fasting is not the caloric depletion, it is the compressed feeding window. Right. So you could make an argument that yeah, well if you are going to post workout calorically hyper compensate, it's going to be breakfast. Well, maybe you're going to have breakfast, you're not going to eat again until dinner if you just decide you're going to have this big ass meal after a morning workout. So it really depends. But ultimately you need to be aware of post workout caloric hyper compensation and then men versus women, there is a little bit of a difference there. It's really interesting. I didn't want to neglect pointing this out to you, but in the studies that have been done on men versus women and facet exercise, what they found found is that women who eat before exercise but then don't eat after exercise tend to burn more fat for a longer period of time compared to the opposite scenario. And men are completely the opposite. Men who fast before exercise then don't eat after exercise tend to burn more fat. And it's related to how women versus men, women tend to be more efficient at burning fat as a of fuel. And so when they're given a little bit of carbohydrates before a workout, they eat a little bit of carbohydrate before the workout and then they go out and they do the workout and then they fast after the workout, they actually burn more fat. And men are the opposite. Men, they don't eat before the workout and then they eat following the workout. We tend to see a little bit of a difference in the sex response to this. Now you need to realize this was done in like lean trained individuals. So I would say, you know, again, a caveat for, for like a really lean trained female would be that you may actually want to again eat something small before a workout. If you fall into that category of a lean active female because I have seen some hormonal issues arise. And the cool thing is if you do that but then you fast after the workout, you still see a really good increase in fat oxidation. So some of the studies have been done on men vs women are really fascinating. And then finally, it takes time. You know, I've talked about this on my podcast before and, and you know, Mark Sisson refers to this as being a fat burning machine or others who refer to it as becoming fat adapted or keto adapted. But the fact is that for you to feel really good doing fasted exercise sessions and for me to do things like go out and do an ironman triathlon on ketosis takes about one and a half to two years to actually build adequate mitochondrial density, fat burning efficiency, beta oxidation, et cetera, to really start to feel like a champ and be able to perform at the drop of a hat in, in any scenario, in a fasted state during exercise. I think people could do it more quickly if we weren't ripped off the ketogenic state of breastfeeding when we were young and then shifted into Cheerios and Gerber baby food and fruit roll ups and all these carbohydrates that we tend to rely upon. And then at age 30 we realized, oh, hey, I should be in ketosis. And we expect it takes two weeks to get into ketosis when we spent the past 29 years teaching ourselves how to become glucose adapted. So it does take some time, but ultimately plan on it being a good one and a half to two years before you really feel like you can crush it. With fasted workouts, you'll still get all the benefits right away, but to feel really good, it does take a little bit of time. So there is a time investment for this.

I had hoped to leave a little bit of time for questions. I'm going to actually skip the summary because there's not a whole lot to summarize. A lot of this is pretty straightforward. But since we have about three minutes or so, I believe I'll take a couple of questions if you guys would like. And I also have a URL again with lots of studies, lots of resources, references, podcasts, all my favorite books on fasting, all those I put up on that website for you. So let's take a couple of burning questions. When you said that for women they should maybe eat a little bit before they work out and then fast after. Are you talking about like have lunch a few, few hours before the workout or like minutes before, have a tiny bit of food? Yeah, in the study it was right before the workout, like, like a pre workout snack type of scenario. And again that's only if you're, if you're a lean, very active female. And then would it be best if it was mostly fat or some carbs and protein well, that was carbs in that study. It was carbs, Yeah. I think you could probably see a pretty good response though by using some of the alternate fuels I was talking about like amino acids or ketones, for example, or MCT oil. So the only time that I am able to work out is in the morning and it would be early, like 6ish a.m. normally though, I'm fasting starting at like 8.30pm and then I don't eat again until like lunch. Sure. Or like a late lunch really. So I guess for me I'm a little confused as far as like, what would be best for me. I don't, I didn't really want to break my fast by eating prior to the workout, but. Are you saying that I should? I. I don't know. Yeah. It kind of depends on your workout, but you know, not doing anything crazy. It's a, it's a light workout. Yeah. Yeah. If it's a light workout, you could, you could get by with just doing a light workout. But I would consider having breakfast about one to two hours after the other scenario that I'll use with, with like some of my athletes were like hardcore athletes, but they did, you know, and Also some, some CEOs I work with who they have that hour and a half in the morning, that's their gym time. I tell them, well, go there, go to the gym and do 30 minutes of fasted aerobic exercise and then slip into the locker room and grab some amino acids and some ketones, then go crush the weights. So you get the best of both worlds. You get the aerobic exercise in a fasted state, then you replenish a little bit, then you go do the hard thing. So that's a scenario too that you can do. You can actually fuel a little bit during the workout. Thank you. Yeah, let's go ahead and get. We got one minute left. So we've got time for one or two more questions. Do you vary dietary changes for insulin dependent diabetics who are endurance doing endurance training, insulin dependent diabetics? Yeah. I mean you certainly have to pay a lot better attention to blood glucose levels, to hypoglycemia, the timing of the insulin. Yeah, I actually have a, I have a podcast that I did on type 1 diabetes and endurance athletes with a guy who runs a triathlon squad for, I think it's called Team Type one, something like that. That would be a good resource for you. Yeah. If you go to my website and do a search for Team Type one, I have a whole interview on that. Thank you. Yeah.

Ben, one more. Yeah, I've read a bunch of your articles and listen to some of your podcasts where you discuss alternate day fasting to get more in an anabolic state. Can you comment a little bit about that with training and how you would vary that? Right. Yeah, it's pretty simple. What I do is I actually alter my macronutrient ratios and go higher protein, more carbohydrates with those carbohydrate refeeds, and dial down the fat on the more active, more difficult days. And then on the other days, it's less carbohydrate, slightly less protein, more fat. I mean, it's that simple. And of course, slightly fewer calories. So when I'm working on a meal plan for somebody, you know, it's not 2000 calories. Like, some days they're at 1700, some days they're at 3000. So we're kind of pressing and pulsing depending on the day's activities. Because for like, for my clients, I'm writing out their exercise program and their nutrition program so I can pair both and partner the nutrition to the actual exercise days. Awesome. Thank you. Yeah, so I've got resources for you up on the website. I also do a lot of mentoring and coaching of my own with a lot of health professionals at key on you. You can learn more about that. We open up enrollment for that again next January. I'll be around most of the day today and tomorrow. If you guys have questions for me about any of these things, I'm happy to answer them or point you to resources. Thank you so much. I appreciate your support.

Want more? Go to BenGreenfieldFitness.com where you can subscribe to my information packed and entertaining newsletter and click the link up on the right hand side of that webpage that says Ben Recommends, where you'll see a full list of everything I've ever recommended to enhance your body and your brain. Finally, to get your hands on all of the unique supplement formulations that I personally develop, you can visit the website of my company, kion@getkion.com that's get K I N.