Scientists Found A New Way to Boost Metabolism (2026 Science)

Imagine that you could burn 600 extra calories per day by changing just one little thing in your diet. That's the amount of energy in this pure fat. Now, when I first heard this, I didn't believe it either, so I get if you're skeptical. But here's the problem: controlled human trials suggest it might be real. And when I tested on myself, because I had to, a self-experiment where I deliberately overate, I actually lost weight. I was shocked, truly calorie confounded. But then, a new study dropped that made it all click. The story I'm gonna tell you today draws from these brand new data that had me, as an MD PhD, with my jaw on the floor. It's a scientific story that took me on a mental journey, bouncing around the literature like a ball on a pinball machine, through crazy human-controlled trials, dietary fads, self-experimentation, and exciting science. That truly changed my mind, my perspective on human energy metabolism. I want to show you what I found and give you a glimpse into the future of human metabolism. Let's go. Participants burned roughly 600 extra calories per day. No extra exercise, no lifestyle change. That doesn't make sense. And a metabolic paradox, the likes of which I hadn't seen in years. What is causing this calorie blasting effect? This is a really important step scientifically.

You can just add like a vanilla whey when you pop it in. An ice cream maker. A little under 9%, something like 1,750 calories.

Okay, here's where we're going. A quick little roadmap to this video. In chapter 1, we're going to go over the most surprising human trial of 2025 and a metabolic paradox the likes of which I hadn't seen in years. And it dovetailed with a bizarre dietary trend that started circulating online, the sugar diet. We're going to get to that in a moment. Then in chapter 2, I'm going to go over my personal fat-burning self-experiment. Then in Chapter 3, I'm gonna bring you to this breakthrough paper. We'll dive into a new study published in one of the world's top scientific journals that begins to explain the biology behind the puzzling results. Then in Chapter 4, we're gonna review the fat-burning cocktail. We'll explore what the researchers attempted to do in terms of isolating key human components responsible for the remarkable Calorie Burning Advantage. Then in Chapter 5, I'm going to tell you what this means for us, for me, for you, and for the future of human metabolic sciences. And lastly, before we begin, a quick note: if you want all the references, extra nuance, practical protocols, and deeper dives into topics like this, you should check out our best-selling science newsletter, Stay Curious Metabolism. Premium subscribers call it an oasis of nuance on the internet and the best $8 they've ever spent.. But plugs for that community aside, let's get started. Let's get to Chapter 1: The Most Surprising Study of 2025. Because to really understand the story we're going to go through, you need to understand this human-controlled trial that found that eating less protein—yes, you heard me, less protein—caused people to burn dramatically more calories. Not a little bit more, a lot more calories. About 20% more. A 20% increase in total energy expenditure. This was not one, but 3 separate human-controlled trials. What the researchers did is they reduced protein intake by human participants to just 9% of total calories. And the results? Participants burned roughly 600 extra calories per day. No extra exercise, no lifestyle change, just diet composition. In fact, the effect was even independent of the other calories present. So even a high-fat, high-carb, low protein diet worked to increase caloric burn by about 600 calories per day, and no meaningful muscle loss. At the time, I assumed the answer had to lie somewhere in human metabolism, but it actually turns out the real explanation might not be human at all. And I'll pay off that tease later, so bank it in your brain. Now, when I read this paper, I had the same reaction most people probably would. That doesn't make sense. But that's where things get extra weird, because at the same time, a diet trend started circulating in the fitness world. People began experimenting with something called the sugar diet. This is my breakfast. I had some Sour Patch Kids, Starburst jelly beans, 8 ounces of apple juice. Sugar on the bottom, sugar on the top. Sugar. The idea was what it sounds like. It was simple. Eat low protein and huge amounts of sugar. Fruit juice, dried fruit, candy. And according to people trying it, they were reporting losing body fat while eating gobs and gobs of sugar, and their exercise performance and strength were actually improving. Ridiculous. Except for one problem. The controlled human data suggests something might actually be going on here, something legitimate. And that brings us to Chapter 2, my fat-burning self-experiment, because I couldn't help it. I just had to test it on myself. So what I did is I gradually lowered my protein intake from around 18% of total calories down to 9%. I cut it in half.

Now, to just give you a sense of what my 9% calories from protein diet looked like, it could be some buttery eggs for breakfast, a bunch of walnuts, and coffee and cream. I think this came out to a little under 9%, something like 1,750 calories with 8% frob protein. So that's what I was eating.

Pretty delicious.

Yolk in the beard.

And I began losing weight. I started to increase my caloric intake to compensate.

Another indispensable tool I used on my low-protein diet was keto ice cream. So it's basically cream, yogurt, sugar-free dark chocolate, stevia. And if you wanted to make a high-protein version, you can just add like a vanilla whey when you pop it in an ice cream maker. Science pro tip: always test your methodology along the way. Yeah.

"Nailed it." I kept increasing. By the end of the experiment, I was eating 500 extra calories per day in surplus. Over the course of a few weeks, I should have added well over 6,000 calories in surplus, which means I should have gained a pound or two. But instead, I lost 6.4 pounds. What that means in a nutshell, a high-fat nutshell, is that my body was burning through far more energy than the calorie math predicted, and by a margin that would make a bomb calorimeter Cry.

Oh yeah, my favorite things is eating the ice cream shards. Oh yeah, and they're so good.

Now to be clear, I'm not advocating for low protein diets. I am though extremely interested in whatever metabolic phenomena is going on here. Ones that challenge our assumptions, because I assume you had the same assumption as me, that low protein will be maybe bad for calorie burning, but here we have the opposite effect. So what is causing this calorie blasting effect? That was a question going through my mind, and can we mimic it without starving ourselves of protein? That's the question we're going to unpack. Can we have our steak and eat it too, or have our steak and eat cake too? And that brings us to Chapter 3: The Breakthrough Paper. Our story now picks up with this new paper published in one of the top science journals in the world, Nature. The researchers set out to answer a very specific question: how do low-protein diets trigger what scientists call white fat browning, or more accurately, white fat beiging? And to understand why this matters, what jargon I'm talking about, we need to take a quick detour into the strange taxonomy of body fat. There is white fat. This is the typical storage fat most people think about. It stores excess energy. Then there's brown fat. It, by contrast, acts more like a metabolic furnace. It's actually derived from muscle stem cells. It burns through fuel actually faster than muscles through a process called thermogenesis, which just means heat production. And then there's beige fat. This is ordinary white fat that can actually transform into more metabolically active brown fat-like state. And that raises the key question: could protein restriction be beijing white fat to increase its thermogenic calorie-burning potential? And the short answer appears to be— yeah! The next question though, this is the interesting one, and how? This paper contains a truly gargantuan amount of data, and I know I have a tendency to be long-winded, "Endothelial nitric oxide synthase uncoupling caused by reduced vascular tetrahydrobiopterin availability." So I'm gonna try something different and jump straight to something that should make a big impression. The researchers looked directly at the fat itself in humans, and what they found was strange. Some people had fat that appeared almost completely metabolically silent, while others had fat that was burning through calories like a furnace. Same species, completely different metabolic behavior. You can actually see it here in these special FDG PET images. This is an imaging technique that tracks glucose uptake across the body. Areas of lots of fuel consumption show up dark on the scan. And what you see here, on the far left of the spectrum, participant labeled T07, is an individual who shows essentially no detectable brown or beige fat activity in these regions. Now, if you want a little peek into my double-nerd mind, when I saw this graph and looked at that participant, I imagined like Lord Voldemort casting a spell on mitochondria. "Metabolus Tardis!" Then, at the other end of the spectrum are participants highlighted in red, individuals showing very high metabolic activity in these fat deposits visible on the scans, these dark regions indicated by the arrows in red. It's kind of like Dumbledore now entering with his metabolism speeding up spell, "Thermogenesis incendiae." Sorry, I'm a super nerd, I know. In other words, some people have fat that is metabolically quiescent, while others have fat that is actively burning through fuel, even at rest. I know what you're thinking now. Some of you are probably thinking, "Ugh, the profound metabolic injustice." To you I say, hang in there, please. The researchers then asked an obvious question: what makes these groups of participants indifferent? And that brings us to Chapter 4: The Fat-Burning Cocktail. So to cut to the chase, the researchers eventually identified the mediator of this calorie-burning effect: the human gut microbiome. But that raises an even stranger question. If microbes can control how many calories we burn—me, you, Why do some people naturally have microbes that help us burn through calories while others don't? Ferment that question in your mind as we move forward, because we will answer it. But let's return to this idea of low-protein diets in humans boosting metabolic rate. Now, when protein intake drops, this signals to the microbiome, a bridge between the outside world and your body, causing it to change composition and change the hormones it produces, particularly hormones called secondary bile acids that influence metabolism. And these changes, the researchers found, activate not one, but two key pathways, one called FXR and one called FGF21, which we've talked about before. The easiest way to think about it is like a lock that requires not one but two keys. One key alone, one pathway doesn't work. You need to activate both keys for the lock to open. And when you open that lock, you get white fat transforming into this metabolically active beige fat that just burns through energy. So to review, this appears to be exactly what happens when protein intake drops. The microbiome, ships, hormones, bile acids change, and those signals together activate the dual lock, both pathways simultaneously unlocking a metabolic program that increases fat beijing, fat browning, and thermogenesis, energy burning. So in the most concise possible version, low protein diets reshape the microbiome, which alters hormonal signaling that then activates two coordinated metabolic pathways that together trigger fat Beijing. But this raises an even stranger and more promising question: if the microbiome is driving the effect, could we reproduce it without changing our diet at all? Can we have our steak and eat cake too? Faced with this complexity, what did the researchers do? And sure, a lot, kudos to them. But one of the most important experiments they performed was a classic causal test in microbiome research, termed fecal microbiome transplants, or more simply, poop transplants. The researchers took microbiome samples from human volunteers in the study and transplanted them into mice. And the results were striking. When mice received microbiomes from humans who had high brown fat activity, high beige fat activity, the mice themselves began showing increased fat browning, beiging, and thermogenic activity. But when the mice received microbiomes from humans with low brown and beige fat activity, that effect largely disappeared. This is a really important step scientifically because it moves the story from correlation to causation. In other words, it strongly suggests, I'd even say it proves, that the microbiome itself is mediating the fat-beiging thermogenic calorie-burning effect. But the researchers didn't stop there. They set out to identify which specific microbes were responsible. The ideal outcome here would be to find the smallest possible combination of bacterial strains, a little team if you will, that could reproduce this effect. In theory, that would make it possible to design a targeted probiotic capsule mimicking the metabolic response, the metabolic benefits, the calorie-burning benefits of a low-protein diet, and no, you don't have to give up steak and eggs. That's exactly what what the researchers did. The researchers were ultimately able to assemble a defined cocktail of bacterial strains associated with a low-protein diet. They called this microbiome consortium HU4, presumably shorthand for human-derived and for strains. And when the mice received this HU4 human bacterial cocktail in combination with a low-protein diet, the metabolic effects became even more pronounced. Compared to control mice, the mice that got the human 4 microbiome cocktail showed greater body weight loss, greater fat loss, maintenance of muscle mass, lower fat in the blood, lower triglycerides, and lower blood sugar levels. Taken all together, this is something truly exciting. The findings suggest that a specific, pretty minimal microbiome cocktail, a group of microbes, can amplify the metabolic response of protein restriction, increasing fat beijing and energy expenditure, blasting through calories. Now, to quickly add a nuanced note and double-click on the muscle preservation effects, what might be happening in the body is the metabolic shift associated with this dietary change or microbiome cocktail leads to the production of hormones like FGF21 that protect muscle. And you can find more details on that in the newsletter below. But anyway, that brings us to Chapter 5: What this means for the future and for me and you. Remember where our story started. The original signal, the strange observation that protein restriction increases energy expenditure, lasting through calories, this was seen in human controlled trials, not one, but three. What the researchers of this study appear to have uncovered here is not merely a mouse curiosity, but a possible mechanism linking dietary change, the microbiome, and human energy metabolism in a profound new way. And if that interpretation is correct, and I think it is, it suggests that the metabolism-boosting effect of a low-protein diet could be mimicked, perhaps within the next few years. In fact, I put my money on it. But I think that also reveals a broader important point about why it's so important to study metabolism, why it's so important for me to be here communicating with you and you communicating with me. Once we understand the mechanisms behind metabolic phenomenon, we are no longer limited to the original trigger that revealed them. You don't have to give up your steak to get these calorie-blasting effects. We can innovate. But that brings us to the section on actionable insights. What can you do today? Now, in the long run, as I mentioned, I believe we're on the cusp of commercializing insights based on these data, developing engraftable therapies such as targeted probiotics or microbiome transplants that reproduce the metabolic advantages of certain dietary interventions—not limited to protein restriction, basically any dietary intervention—without actually having to adopt them directly, or perhaps, more likely, synergizing with dietary interventions, amplifying their beneficial effects. But admittedly, we're not there yet, and I hope that's not disappointing, it's just honest. So the question is, what can we do in the meantime? Well, you know I'm a big advocate of the n=1 approach. While I don't advocate chronically low protein diets, I do think that safe, controlled n=1 experiments can be very informative. Because as much as we emphasize rigorous data, human-controlled trials, and rightly so to some extent, there is something uniquely illuminating about experiencing a physiological phenomenon in your own body for yourself. I can definitely speak to that in this case, which is why I'm so animated and excited. When I ran that experiment where I reduced my protein intake to about 9% of calories, I'll be honest, I was nervous, but I was curious too. And what I observed, what I felt, was undeniable. Now, if you do decide to experiment with a low protein approach, and I'm not per se advocating for it, but I realize you're curious too, I would suggest doing it through eating a whole foods diet, not a sugar diet. I hope that's logical, but a little confusion arose when I did my prior sugar diet video, so let me clarify that. Now, when I ran this experiment on myself, I actually leaned towards a low protein ketogenic diet, and that actually brings us to another potentially actionable insight. Can ketogenic diets enhance fat beiging and browning and reproduce the effects we just discussed? Well, let's dig into reference 22 in the paper we just reviewed. It describes a fascinating animal study showing that ketogenic diets were sufficient to increase energy expenditure and promote weight loss by causing brown fat activation. Let me draw your attention to this image. This is electron microscopy, extremely high-resolution imaging of brown fat tissue. And the key feature I want you to focus on is that letter M, which stands for mitochondria. Under the ketogenic diet condition, shown on the right, the mitochondria are larger and more abundant compared to those animals on a standard control chow diet. The ketogenic diet mitochondria just contain more mitochondrial proteins, more uncoupling proteins, indicating greater thermogenic energy-producing capacity. And at the same time, look at L. These are lipid droplets. They've become smaller and more numerous in the brown fat tissue, increasing their surface area and making them more readily accessible for energy use. So in other words, put simply, the ketogenic diet forced brown fat tissue to undergo structural remodeling. The mitochondria essentially bulked up, became more powerful, increasing their energy-burning capacity, while the fat droplets became more accessible fuel sources. The net result was that these animals burned through more energy despite consuming the same number of calories. I'm sorry if we just made another bomb calorimeter cry. Now, exactly how much of this metabolic advantage comes from nutritional ketosis, carbohydrate restriction, or even protein restriction is still unclear. My best guess is that it varies from person to person, or mouse to mouse, but I certainly think it's at least possible that ketosis itself may enhance thermogenesis, at least in some individuals. Finally, in terms of actionable insights, I just want to take a step back and talk about caring for your microbiome broadly. Because one broader lesson from everything we've just covered is that the microbiome plays a major role in mediating how environmental inputs like diet affect metabolism. So, for the sake of simplicity, if your microbiome is good and healthy, you're more likely to benefit from various dietary and lifestyle interventions and vice versa. To that end, I'm gonna briefly share my own gut health routine just for transparency, it's pretty simple. Principle 1: Time-Restricted Feeding. I restrict my eating window to an 8-hour window typically between 10 AM and 6 PM. Intermittent fasting has several potential benefits that go beyond weight changes. This includes acting as a circadian signal, what's known in the scientific literature as a Zeitgeber, which is just a word I like to say. It helps coordinate the body's biological rhythms. Second, I eat effectively no highly processed food. Now, I know processed food is a vague term, but just use common sense to some extent. I largely avoid ultra-processed foods or products containing artificial sweeteners, emulsifiers, things like sucralose, aspartame, etc., which can disrupt the microbiome and cause insulin resistance. Third, I include fermented foods in my diet where possible. For me, that includes things like live culture yogurts, sauerkraut, and goat milk kefir. I've also considered adding natto, although I'll be honest, it's just somewhat difficult to source where I live in Boston, Massachusetts. That said, there's a lot of really promising data on natto, or more specifically an enzyme in natto called nattokinase.. So if you found this video interesting, definitely check out this video next. Lastly, and I always get a little bit shy about plugs, I do take a probiotic by Winnow Labs, which is designed not only as a top-in-class probiotic, but also to bind microplastics in the gut. Now, if you've followed my work for a while, you've probably heard me talk about this issue. Microplastic exposure is increasing worldwide, and there's growing concerns about its impact on human health. I won't get into the weeds in this video, I just want to spare you the time, but if you're interested, you can check out these prior piece of content on microplastics and heart health and brain health, dementia. So to that end, transparently, I personally take 2 capsules of Winnow each morning as a sort of microplastic insurance, but also because it's simply a very high-quality probiotic. That's not mine. So if you're interested, you can use my discount code STAYCURIOUS or check the referral link below. But I also want to clarify, I'm not mentioning this as just some random Force plug. I really want to share it because I genuinely like the company, the work they're doing, and I'm trying to help them on the back end with exactly what we're doing together here and now, learning about the frontier of the microbiome and metabolism. And when interesting data like these that we just discussed surface, I try to communicate it to the private sector. The goal here is to help accelerate development of the kinds of tools and therapies I think many of us want to exist. I know because I certainly do. I do for myself, for my family, and for you. And I thought that was worth sharing. But wrapping up for real, maybe the real lesson here is progress in science rarely begins with certainty. It begins with confusion. And you should immerse and enjoy that moment with a result that makes you stop, stare at the data, and think, this can't be right. Those moments are uncomfortable. I get it. They challenge our models, our assumptions, sometimes even the foundation of what we think we know for certain. But they're also where discovery lives and thrives. Because when the data refuse to fit the model, one of two things have to change: the data or the model. And I think it's way more interesting when the model changes. That is how science moves forward, not by confirming what we already believe, but by confronting what we don't understand. The odd observations, the what the heck. And if this line of research continues to hold up, it hints at a remarkable possibility: that one day, maybe soon, we may be able to tune human metabolism by carefully modulating the biological systems that decide how energy is burned in our body. And that possibility began the same way many breakthroughs do: with a paper that looked Totally wrong. Until it wasn't. Which is why— stay curious. Thanks.