I've been hitting the gym for a few months now, and one thing that completely blew my mind was the existence of hypercalorics. Imagine that, not being able to eat a lot (specially carbs) and having to resort to these solutions. Point being, people like to spew out CICO as if fat people just don't understand thermodynamics. What I've found is that matters is appetite: some people just get full way faster than others.…
This is a half truth. If you cut down portion size your stomach will shrink over time. I eat a lot less before feeling full now, and I only changed my life a year ago.
It's also important that you eat stuff that makes you feel full, fibers and greens. Changing diet also changed my taste, so I crave more healthy things now, while the food I used to eat honestly don't appeal to me any longer or tastes empty.
OTOH if you push yourself to eat a little more every meal, your stomach will grown, accommodating room for more before you feel full.