During the Covid lockdowns, like millions of others, I watched YouTube to kill time. This included fitness content. I was among the 40–60 percent of people who gained weight during the lockdowns (in their infinite wisdom, the “experts” decided a virus with a ~100% survivability rate for healthy adults necessitated shutting down the economy). I finally lost the weight, and more, around early 2023. This got me into studying metabolism. I had already written a ton about IQ when I started my blog, but other aspects of human biology, such as weight, I ignored.
Twitter, unlike Instagram, is not a visual medium, but it’s still impossible to escape the grip of fitness culture. Political commentary is juxtaposed with dieting advice and viral “before and after” transformations. But as I continued to consume fitness content, either of my own volition on YouTube or through recommendations on social media, I kept wondering how some people were able to lose weight and become lean, whereas most people struggle, even when cutting the calories really low and doing lots of cardio.
Yes, undisclosed drug use can play a role (as well as calorie miscounting), but many of these people insist they are drug-free, and I want to believe them.
Drug use is only part of the equation; it doesn’t explain how some individuals can become lean without drugs. In other words, it’s more likely that there is another factor involved than that everyone is on drugs. Millions of people online follow this “commonsense” dieting and fitness advice, without the sought-after leanness to show for it. People cut the calories low and the weight simply does not come off much. This is corroborated on Twitter and Reddit, as well as in YouTube comments.
So what is going on here? This dieting advice is claimed to work, and in principle it should. But it doesn’t, except for a minority, those being influencers and maybe a few others. I decided to treat it with the seriousness of a science problem. This led to my own research about metabolism. Enough with the videos; instead, I read studies and gathered testimonials online from people trying to lose weight, along with their recorded calorie consumption. This led to my first hypothesis: the slow-metabolism explanation for obesity.
Obesity is a major problem worldwide. “Hyperpalatable food” (or simply, junk food) and inactivity are commonly blamed. This has never struck me as useful. Really, how much more inactive are Americans today than they were in the ’70s to ’90s? TVs, cars, and “office jobs” were commonplace back then. Gym attendance was much lower, too. Same for junk food: chains such as McDonald’s and KFC were household names. This is assuming we can even define what makes food “hyperpalatable” or “processed.” Preserved and canned goods, for example, were common well before obesity became a problem.
Other explanations include seed oil consumption. Or falling testosterone levels. But overlooked in the discussion is the role of metabolism. My thesis has been that metabolism plays an underappreciated but vital role in the sustainability of a non-obese body weight. The crux of my argument is that if someone is obese despite not consuming that many calories relative to weight & height (as predicted by regression equations), then this leaves less room for calorie cutting.
The “black pill” is that for many of these people, the number of calories they can eat without being obese is set very low, likely by bad genes/biology, as metabolism, similar to IQ or height, does appear innate (again, when controlling for factors like weight, height, and lean muscle mass). So these people are pretty much screwed unless they can somehow sustain Minnesota-starvation-level rations for life. Yes, life (with no guarantee that dieting gets easier or the body becomes less efficient with time).
This does not answer the question of why obesity rates have risen over time, especially since the early ’90s. Genes change far slower than the environment. But metabolism can explain variability between individuals in regard to weight loss success, leanness on social media, and resistance towards not being obese, when the environment is held constant. Having a higher baseline metabolism to begin with means more room to cut calories. This is useful as it pertains to “cutting” when trying to be lean on social media.
Then there is the second question: why do some people not become obese at all, or quickly lose weight after becoming obese and not regain it, as in my case? It’s easy to forget that 25% of Americans are NOT overweight or obese despite headlines about obesity. People tend to gain weight as they age, with obesity rates climbing to a peak at 60–70:
But excluding people with serious illness, drug abusers, anorexics, or those who do excessive cardio, the percentage of men past, say, 40, who are able to maintain a BMI of 25 or lower without much effort and while not restricting food much or doing excessive cardio must be lower than 25%. So who are they? This led to my second hypothesis: the brain-body gap explanation for obesity, which I came up with a month ago.
So basically, the brain wants “x” calories, but the body needs “y” as measured by resting metabolic rate (RMR), where x>y and both lie on a normal distribution. This makes sense because if x
The estimated risk of gaining more than 7.5 kg in body weight was increased fourfold in persons with a low adjusted 24-hour energy expenditure (200 kcal per day below predicted values) as compared with persons with a high 24-hour energy expenditure (200 kcal per day above predicted values; P less than 0.01).
Conversely, good genetics would mean a very high value of “y”, with a high value of “x” to match as predicted by x>y—but not such a wide gap as to make it too easy to become obese. “Fitness people” who seem to stay lean year-round relatively easily despite eating lots of food, I posit, fall into this category. This also makes cutting easier too, as explained in my post, “Bulking, Metabolism, and Selection Effects.” This has not been studied closely. It’s just a hunch based on self-reported calorie counts and how audience members report lower calorie counts and worse success when following said advice of the influencer, as mentioned above. This is what led to this research.
Activity can help close the gap, but this requires vigilance. So this can again explain how people become obese by being sedentary. The gap can also explain the small but persistent percentage of obese people, even in the 1950s, before hyperpalatable foods were common. It also explains why dieting often fails, because the gap never closes. When weight is gained, both values go up, but the gap persists. The fact that x>y can also explain gradual weight gain as people age, irrespective of the size of the gap.
My model also explains why GLP-1 drugs work so well. The drugs make the brain want less food by suppressing the “reward system,” but also by creating the sensation of fullness sooner. For people with good genetics, if they need the extra dopamine hit from food, they overeat and can get fat, but because the baseline gap is so small, they can quickly lose the weight when returning to baseline. This can explain how a small minority of people succeed at dieting (e.g., actors who gain weight for a role and do not seem to have much difficulty losing it), as a narrow gap again makes cutting easier.