Greetings!
Yes, indeed others think along those lines 8n a world that is, in effect, a giant recycling system from any perspective.

As far as fat goes, if I remember my biology lessons correctly, we never lose fat cells, per se. However we can grow them. We can add to the number of fat cells, but not get rid of them once created.

They fill up or are depleted depending upon diet and the body uses the fat for energy necessary to heat the body to protect from cold or to provide fuel for exercising of the body (physical work). So when the fat cells are filled up we gain weight. When the fat is metabolized and no more fat is added, we lose weight. Of course the endocrine system is in play here as well. This is the way it goes if the endocrine system is in a healthy balance. Which, of course is rare these days. Funny thing about the endocrine system: Modern medicine, to this day, NO ONE knows exactly how this complicated system really works!! This information is still hidden from us in this world of petroplastic "paradise"! Which of course is never considered when pushing the opt out of fossil fuels...yep... plastics of all kinds are petro based...but that is another thought to ponder...