How does the body regulate appetite?

Sometimes we eat when we’re not hungry or fast when we are, but actually, our bodies have a complex system for telling us when we need food. When we feel hungry it’s because the stomach wall signals that it’s empty, and when we feel full, it’s because the small intestine and pancreas send signals to the brain to say that we’re not hungry anymore. Our fat tissues also send signals to say we have enough fat. One reason it might be hard to stick to a diet is that as you lose body fat the fat tissues send fewer signals, but the stomach wall will send more.