We don't need a complicated explanation, the simple factual explanation for Americans being the fattest people in the world is, they eat more calories than anyone else.
3,600 calories per day is the maintenance weight for 350lbs man who exercises 1-3 days per week.
Depending on distributions there’s some wiggle room, but if the average calorie consumption were anywhere near that high you’d expect to be average weight to be about 150 lbs more than it is.
That's why kids who grow up eating unhealthy can look healthy for a while, but eventually they look like their parents. And once the body is out of buffer, any extra calory goes straight into storage
Basal metabolic rate does go down with age, but basal metabolic rate and total energy expenditure are mostly stable between 20-60. A 60 year old burns about 122 fewer calories than a 20 year old.
What happened is that the kid is either eating more, or is exercising less.
A normal 20 year old who isn’t an exercising a significant amount can’t regularly eat 3600 calories and maintain a healthy weight. That is to say, the average 20 year old with a healthy BMI who exercises 1-3 times per week will gain somewhere around 2 lbs per week eating 3600 calorie per day. They’ll gain less over time if they don’t start eating more as they get closer to 350lbs because their maintenance weight will go up.
And despite individual variation in BMR, I haven’t heard any evidence that some people have the ability to significantly ramp up their metabolism in response to consuming more calories.
But portion sizes are very small. Workers doing heavy construction work will have a large bowl of pho for lunch. That's like 400-500 calories. They are super lean and muscular.
That's not an answer, though. Or at least not a root cause.
Why are American portion sizes bigger?
Why do I need to eat more American food to be satiated?
In China, I'm regularly taken out to banquets, where people stuff themselves until they can't eat anymore. I do too. I still lose weight. Other places, we feast too. I'm then full for a long time.
In the US, I'm back to hunger pangs a lot more quickly.
What does it mean to engineer satiety? An example is Doritos, they are a food which has been very effectively engineered to compel more consumption without making you full. More consumption and less satiety equals more revenue. Lots of American junk food is engineered with this principle in mind.
A roast duck with some rice and vegetables or something at a banquet will have much better satiety per calorie than Doritos and Hot Pockets, or most typical fast food meals, probably even fast casual meals etc.
That's very insightful.
What I don't quite understand, though, is the lack of satiety even from American food not engineered like this. There's a big difference between basic foods like meats and vegetables between the industrial crops of the US and ones from local farms in less industrialized countries.
My hypothesis -- with zero evidence -- is that industrial foods are lower on some nutrient my body needs, and my body wants to eat to get enough.
Protein is notably declining across staples. Protein is not substitutable like carbohydrates. Meaning that your body will trigger you to eat until you get enough protein. Conversely, if you have an abundance of protein and the various micronutrients or vitamins your body can happily convert protein to carbohydrates via ketogenesis. One can subsist on a nearly complete protein diet so long as nutrient deficiencies causing diseases like scurvy are addressed. The same is not true of fat or carbs.
Food or environmental, but in a larger sense, it's likely to be some additives, is my uneducated gut-feel (pun unintended) guess. Here by additives, I don't mean only ones in food, but also fertilizers, pesticides, other synthetic chemicals, and agricultural and industrial effluents.
It feels like there is a pick 2 situation between lean body, being full of energy and being satisfied by food
I’d put money on this not being the case with McDougall, if you follow it strictly. I’ve known several dozens of people personally who have switched, and he has a few published papers on many hundreds of patients. You eat as much as you want. It’s quite hard to keep the pounds on until you hit some natural base weight. (I had to add some fats back into the diet after a while because I otherwise look too thin.)
It should be noted, if you’re on insulin, you need to see a doctor when starting the diet, because you’re likely to need to reduce or eliminate your insulin pretty quickly. Same is true for blood thinners, blood pressure meds, and a number of other drugs. If you’re on a lot of meds, it’s probably worth going through his 12 day program.
I’m unaffiliated— just have personally seen the reversal of supposedly genetic disease and am a fan.
I put on weight in the US no matter what I eat if I eat until I'm full. I naturally drift up by about a pound a year, and faster if I recently dieted. The only way to lose weight is to be constantly hungry. I will sometimes do that for a few months to get my weight under control. It then wanders back up. I've tried all sorts of diets, including plant-based, and it doesn't help. I need to be hungry all the time.
I find it easy to lose weight in less developed countries, even eating what would be considered much less healthy food in the US (fried fatty food, lots of meat, etc.). The food also tastes more, for lack of a better word, real.
I'm not sure we have any clear sense of what, in out hyper-efficient industrial food economy does this. Come to think of it, we don't even know it's the food -- could be something else environmental.
But that's how my own body behaves.