Do we become hungry because our stomach is empty or is it because of something else?

That is a tricky question. There are people who have studied this
and can boil it right down to all kinds of enzymes and
mechanisms that kick into play, stimulating appetite or
depressing appetite.

When I go out to exercise and I get back and sit down, I need to
replenish my water intake. The next thing that I find is I find a combination of fruits to eat, primarily because they are made up
of water, and sugar carbohydrates. But the digestive process is
pretty rapid when it comes to breaking down sugars into glucose.
I can consume a lot of fresh fruits and it doesn’t satisfy my
hunger.

I will still have hunger pains because the digestion is completed
so rapidly as opposed to protein, which takes longer. It almost
seems like exercise can suppress appetite but I think you have to
balance that whole idea with how much exercise you are doing
and how many calories your body needs to replace and what
kinds of food you are going to consume.

It is complex and is another whole area to think about as to why
people are gaining weight, whether it is emotional or whether it is
the amount of exercise they have done.

Everyone studying this issue, trying to help people lose weight,
may have their own theories and their own recommendations.
They all study it in a different way - some try to understand the
psychology and some try to understand the nutritional aspects of
it. If it was well understood, we probably wouldn’t be having the problems we are having today.