People don't realize how wildly appetite varies between individuals. Thinner people tend to think they eat a lot, because they're fulfilling their appetite. Fatter people often think they don't eat that much, because they're rarely full. IME, that's the thing that varies far more than actual metabolism stuff.

Yeah this is correct. I eat whatever I want, snack a lot, etc. Never been fat because I just don't eat that much in aggregate.

I averaged 4,000+ calories per day in high school through the first couple years of college. Almost all junk food—pizza, chips, crackers, eggo waffles, french fries, that kind of thing. Enormous amounts of soda. Milk shakes. Cappuchinos and mochas, in the later years.

All I did for activity was ride bikes some and lift weights a little, plus usual kid stuff, no serious sports or training.

I had visible ab muscles and would get a full-on six pack if I did e.g. a lot of swimming in a week. During those times I'd have relatives concerned I was sick or something, my face would get so gaunt.

Metabolisms are weird. HGH and T are basically magic I guess? I truly have no idea where all that energy was going. Must have been mostly coming out the other end unprocessed, I suppose, or else somehow used up by my gut biome. Can't figure any other way.

> I truly have no idea where all that energy was going.

Growing your body. I was the same in my late teens and early 20's. Family called it the POW Aesthetic. 6'1" & 150lbs, couldn't put an lb more on. I was strong as shit though, in a practical sense. No issue throwing 100lb feed bags over a shoulder and walking it up some stairs into storage, things like that. I was both doing active things all the time, and finishing growing my body. The summer I got my last growth spurt was agony, my bones hurt every night and I was a bottomless void of hunger.

Also, do not underestimate this bit:

> All I did for activity was ride bikes some and lift weights a little, plus usual kid stuff, no serious sports or training.

Specifically I believe the "usual kid stuff" part was doing a lot for you, I know it was for me. Looking back I now realize that my "usual kid stuff" was me being very, very active. I was pounding out 20k+ steps a day just moving around the family farm, miles on a bike (often on grass too), and then maybe an hour of pick-up soccer in the evening. This was just normal activity for me back then, I would not have considered any of it Intentional Exercise. Today I'd have to intentionally train for an ironman to even start approaching that level of activity.

I gained 15lbs the _summer_ I got my first desk job, that was entirely because I replaced 8 hours of walking around and doing things with 8 hours of sitting in a chair, and about 30 minutes of walking for breaks and lunch.

Right, me too, which lead me to one conclusion: the root cause of obesity isn't overeating, it's a propensity to overeat. I don't have that propensity so I'm not obese, and probably won't be, unless that changes.

It's the same way I kind of view alcohol. Alcoholics are always alcoholics, even if they don't drink. Because drinking isn't alcoholism, having the desire to drink to the point of self-destruction is alcoholism.

Yep. I have IBD and have to track calories to keep my intake _up_. It's shocking how much food you have to eat to get much more than 2k a day.

It's not at all difficult if you are eating junk food. For example a single Medium Pizza alone is enough to fill your entire day's worth of calories.

I know because I've experimented with this when I started measuring my weight, heck sometimes having a single Wendy's Baconator will not only fill your entire calories but even make you gain weight.

Your activity levels of course also matter but I'm assuming sedentary lifestyle.

This is much more different for healthy foods however.

I get sick of junk food quickly (and sometimes sick from junk food).

Counter-anecdote: I have a smallish build and have well-tuned satiety, but a consistent measured TDEE of 2400~2500 kCal, and would go hungry and waste away at 1.5k.

I agree there’s no substitute for measuring your numbers. But meticulous calorie and weight tracking is probably a big ask for the average person, even though it’s imo absolutely necessary for controlling your weight one way or another.

Spending some months with a TDEE spreadsheet can be helpful but requires logging a lot of CI and weights -- if you go to any online TDEE calc you might overestimate your activity level.

I was surprised that running 6h/week and 15k/steps a day gave me an TDEE activity level at barely above "Light Exercise" and I need about 2460/day.

The "Moderate" activity level is if you actually work construction and haul bricks all day!