JJ Virgin explains why your brain needs 100-130g of carbs daily: glucose is its preferred fuel, and neurons use twice the energy of other cells. Cutting carbs forces your body into inefficient ketone production, causing brain fog and fatigue. Women over 40 are especially vulnerable due to hormonal shifts that amplify these effects.
So let's talk about how avoiding carbs might impact energy levels, your brain function, and your overall health. Now, here's the deal. Your brain is a carb lover. It requires about 100 to 130 grams of carbohydrates a day to really function optimally. Why? Because glucose, which comes from carbs, is the brain's preferred fuel source. And neurons demand twice as much energy as the other cells in your body. So carbs are essential for mental clarity and focus. When you cut carbs dramatically, your body will either need to start using ketones or it will need to convert protein into glucose. This is not an efficient process though. And that's why you can hear, you've heard about like the keto flu. You might feel drained, you might feel foggy, might zap your energy and make just simple things that you can normally do, like hard to focus on. And again, if you've ever felt foggy or forgetful on a low-carb diet, your brain needs time to make a shift. Your brain can run on ketones, but it needs time to do that. And so what you're feeling is your brain not getting what it needs. Also, remember, low-carb diets can disrupt serotonin production, and serotonin is that feel-good neurotransmitter that regulates mood and focus. So without enough carbs, your brain struggles to produce serotonin efficiently. It can make you irritable, more tired, and just kind of have crappy cognitive function. This is especially true for women over 40. Hormonal shifts during this time make the brain more sensitive to energy fluctuations, so cutting carbs just basically amplifies those symptoms of brain fog and fatigue.
