"And happiness is thought to depend on leisure; for we are busy that we may have leisure, and make war that we may live in peace." -- Aristotle. Nicomachean Ethics.(X.1177b4). c. 325 BC.
Sugar can heighten insulin and make you sleepy after the initial high from the sugar. I guess this can be like depression.
Okay, I can see being overweight possibly leading to depression. But to assert that having an extra sweet, sweet tooth could be a sign of depression I think goes too far. I mean, it could just be a sign that he or she like candy. Taken to it's extremes anything could be a sign of almost anything else.