[mateo1]

It's not just that. I'm pretty sure your stomach and gut also provide information regarding caloric intake, on top of other sensors detecting the raise in blood sugars/lipids/aminoacids. And even if it didn't, you'll get hungry when your body/brain detects you've switched to using reserve power. If eating doesn't satiate the hunger by providing energy, the response would likely be to make you hungrier and hungrier.

[arghwhat]

Well, "reserve power" is from starvation, intense exercise, or weird diets, not hunger.

From brain perspective, "reserve power" would be when it ends up relying on ketone bodies, which start to be produced in higher numbers when you have been in high glucagon, low insulin condition for a longer period of time. Long enough that the liver burned through its glycogen stores and the liver cells redirect oxaloacetate to gluconeogenesis (producing glucose from stuff in the blood) to the point where the cells become unable to finish its own metabolism of free fatty acids. It then turns the intermediate products it can't use itself into ketone bodies.

That part can be regulated with nutrition, glucagon and insulin, but having plenty of glucose won't replace sensations from the digestive system itself.

[sethammons]

Your gut bacteria is amazing - it will signal even what kids of food it wants. By passing those hungry bacteria will eventually kill of those specific cravings I guess, but meanwhile, I'd wager a lack of satiation if bypassing the gut.

[mcmoor]

Yeah I've heard that the reason artificial sweetener makes people fatter instead is that the body feels robbed when they don't get the supposed caloric intake they should get when eating something sweet. So they crave more.

I actually do feel it, I still feel hungry if I eat lots of something that has little caloric value. So eating lots of vegetable and water doesn't fool my body into satisfaction.