A lot of people, it seems, are always hungry. Always thinking about food.
Some people spend hours every day resisting their hunger.
Some people give in, and eat until their stomachs hurt. They’re still hungry, but the pain is enough to make them stop.
Some people do both!
I've had a pretty normal metabolism for most of my life, and I can tell you that it's not at all normal to eat until your stomach is full. Not at all normal to feel hungry if you’re already carrying as much fat as you should be carrying.
But recently I've become aware that a lot of young people, Americans particularly, seem never to get the feeling of 'I've eaten enough', at which point the thought of further food is aversive.
My generation call that 'fullness', but we don't mean that we're physically full and there's no more room!
We mean that we have stopped wanting food to the point where we won't want to eat any more even it if it's really good and right in front of us.
In the absence of that feeling of satiety, it seems people literally eat until their stomachs hurt.
I can do that, but I wouldn't do it normally, I'd have gone off the idea of food long before then unless I was in severe calorie deficit. Sometimes I've done it for social reasons, but if I do, I feel ill, and I don't feel hungry for days afterwards.
I think it's the key to the whole mystery of obesity.
I'm fat because an exquisitely balanced homeostat that's worked all my life seems to have become slightly miscalibrated (by about 20kcals/day) over the last decade.
I wonder if in most victims of the obesity epidemic, that homeostat is just completely broken, like a central heating system where the thermostat has stuck, or a car where the fuel warning light is always on.
There are many mechanisms that fall under the heading of 'appetite', and all can become deranged in ways proper to themselves: PUFAs, emulsifiers, hidden sugars, comfort eating, impoverished gut microbiome, inflammatory factors, highly palatable foods, yo-yo dieting metabolism, you name it.