A 2015 study from Brown University found that you’re likely to have less belly fat if you have a high degree of “dispositional mindfulness” — where you’re naturally inclined to pay attention to your present thoughts and feelings. The researchers speculated that this kind of “everyday mindfulness” helps overcome the instinct to stock up on calories, which are not in short supply to use modern humans.
This could be because the body increases insulin secretion in anticipation that sugar will appear in the blood. When this doesn’t happen, blood sugar drops and hunger increases. Whether this chain of events regularly takes place is somewhat unclear. Something odd happened when I tested Pepsi Max though, and there are well-designed studies showing increased insulin when using artificial sweeteners.