I'm sure someone can point to a good writeup on this.

I'm a firm believer that this explains a ton with initial success, later failure, and a host of sub questions.

All food we take in has to be digested, absorbed, or eliminated.

This process is largely regulated by gut bacteria. We are amazingly adaptive creatures with amazing guts.

Most diets work short-term , I believe this is due to caloric restriction. Inadvertant restriction. As we change our dietary intake drastically, our guts have to adapt to the new caloric source.

Now before we explode into calories in vs out debate, this is calories in vs calories absorbed, an inadvertent restriction in calories

Those people that eat all they want without gaining weight likely have horrible gut health and poor food absorption

Those of us that look at food and gain are simply efficient

Those of us who lost heavy, and started regaining may have simply healed our gut and adapted.

I say this for people eating static amounts, the obvious solution is to be completely honest with your body and not follow societal eating norms and only eat when and portions as you feel you need for satiety.

I find I eat less now than when I started, yet I'm still packing on muscle... But my eating schedule is now erratic ...