FWIW, I went like two months managing to barely eat anything and not feeling hungry--using electrolytes, supplements, and careful decisions about fat vs. carbohydrate intake with respect to satiety--but I swear my body started breaking down and it led me to panic. I am considering trying again and bulk-loading protein at the same time... but I feel like I haven't even recovered yet from trying to eat less the last time. At least I haven't gained back much weight... but I only lost (net) 10 pounds.

Honestly, I just don't understand how people lose weight by simply not eating, as it feels like you have remarkably little control over what your body spends its remaining energy on or even how much energy it chooses to spend.

To flip this: up until a few years ago for me--when a switch flipped and I started rapidly gaining weight for some reason--it was also hard for me to gain too much weight, despite how I cared absolutely not for how much I ate. Like, people act like eating is some choice and that's what causes you to gain or lose weight, but if you try to eat too much it isn't trivial that you just gain weight. My experience is that I'd get full and just not want to eat as much for days after I ate too much, I'd get feelings of more energy leading me to burn more without realizing I was doing so, and I swear your digestion changes somewhat and you absorb less.

Like, what actually causes this mysterious engine to stop regulating itself is crazy. You know what has correlated with my gaining weight? I started feeling cold a lot. I used to never feel cold, but I started getting cold all the time and now I sleep under a giant stack of blankets and it is difficult for me to sleep without them... it is actually ridiculous how cold I get now. My body has clearly decided to stop spending much energy on raising its body temperature.

So like, I can eat less, but there are a ton of ramifications to that and my body starts automatically trying to correct and fight against it and inherently is making energy tradeoffs that I disagree with ("just burn the fat already!" ;P). People do these weird diet regimes--like keto--because it makes them think (maybe correctly!) that it gives them some control over how their body spends that energy budget. I honestly frankly think maybe I just need "more sun" or something stupid like that and I'll lose weight without even trying so hard.

I think there could be even more components. For example eating some foods actually makes me way more hungry than I was before. Take yogurt or (stevia) sweetened, flavored whey protein powder. I'm ok, then I eat some, then I'm ravenous. I'm literally way hungrier after eating those foods than before. Cheese has it, too. Most carbs as well, especially sweet ones I think it might be something about insulin being released from dairy and from sweet taste. Even if it's zero-caloric sweetener like stevia or monk fruit, I feel a spike in appetite 15-30 minutes later.