I’m a biology geek. I especially like human physiology. When I think of the intricacy and infinite complexity of how the human body works in perfect unison, it blows my mind. I’ll spare you the really geeky stuff, but let’s talk a bit about physiology in relationship to exercise and weight loss, things that matter to all of us. There are so many cool and amazing things about our bodies that we never think of, but that play a big role in our understanding, or not….. of the science of fitness, weight loss and nutrition. The epidemic of quick weight loss schemes is a perfect example of how we have ignored human physiology and evolutionary adaptation. 80-90% of quick weight loss schemes won’t work, and sadly, result in rapid weight regain eventually. Here’s why, in real world, “non-scientific” terms.
First of all, rapid weight loss diets cannibalize muscle and thus lower the metabolism. A slower metabolism means less calories burned, even while sleeping! This negative affect is compounded by a second fact: rapid diets also negatively affect major hormones that regulate hunger and fullness. This is because our bodies are genetically designed to store excess energy as fat in order to protect us from quick starvation when food sources are low. Our ancient ancestors, like all animals, naturally over ate when food was abundant. Over eating was never a bad thing. It meant ongoing survival, as fat was stored for future use. Survival of the fittest meant survival of the fattest! Under eating was never intentional (as it is now) as it zapped fat stores. No caveman ever went on the “21 Day Fix” unless it was the winter, and their food sources were scarce.
Thus, our bodies adapted hormonally to encourage significant over eating after a period of fasting. These hormonal signals have not changed over thousands and thousands of years, but our world certainly has. Food is abundant. Over eating is not evolutionarily necessary, and yet we still do it. (This speaks to the void that hyper-satiating foods play for those with emotional eating issues- a whole other blog topic!) On the other hand, half of us are starving ourselves, thinking we can out run evolution.
You can’t fool Mother Nature! Quick weight loss programs/diets/cleanses/scams all eventually signal our bodies to eat- eat- eat by stimulating the same hunger hormones we have succumbed to over the millenniums. “Starvation Diets” increase ghrelin, a hormone which increases hunger. High ghrelin= more hunger. Strict diets lower leptin, the hormone which signals fullness. Lower leptin=lower fullness. And, when leptin lowers, the thyroid also slows. This makes sense; the body is regulating it’s metabolism to accommodate a perceived period of starvation. This is why rapid weight gain, over hunger, inability to stop eating in excess, all can and will occur after a starvation diet. And, with muscle tissue cannibalized, and thyroid slower, boy does weight come on fast and furious! Great if you’re a caveman, not so much if you’re a desk slave.
Rapid weight gain in our ancient ancestors was not an issue. It is with us. We are a sedentary world. We’d all be much better off if we found moderation in eating- a slow lowering of caloric intake over time to produce a patient, positive fat loss. But that’s not sexy. And we want instant results. This is why intelligent, thoughtful people will buy packaged, fabricated foods, loaded with salt and chemicals, without any positive nutritive value, just because they are portion controlled. Or, why people continue to fall for the maple syrup-lemon rind weight loss cleanse…. or some other cleanse that your sister-in-law’s manicurist recommended. Why do we listen to non-nutritionists or non-fitness professionals for our nutrition advice? Maybe because we don’t want to know the real answer. Fat loss is hard work. It takes time and awareness. It means permanent change. And we aren’t so good at that. But it’s the only answer to our nation’s obesity epidemic. What we don’t need is another diet or cleanse.
Lastly, we’d also all be much better off if we moved a lot more. Exercise is a part of the equation, but, really plays a small role in fat loss and weight maintenance. Daily walking, lifting, moving, pulling, pushing, manual labor, and even fidgeting, play a much bigger role in calorie expenditure than exercise itself. So please exercise. But also please walk to get your newspaper, do your own housework, take the stairs, park far away when shopping. Don’t conserve energy, expend it.