The drug Redux was developed by a biochemist who published the carb/serotonin link. His wife used to counsel patients to have some sweet before bed and it will help you sleep. The old milk/cookies = serotonin boost and tryptophan. Redux was recalled for affecting heart valves. But that story is true.

You can release serotonin by chewing also. Gum or anything crunchy is more satisfying for that reason.

The things that help depression:
chewing
sweets/carbs
DHA found in fish oil
B6 which is needed to make serotonin
magnesium which helps metabolize good fats
Proper light exposure for SAD
tryptophan or 5-HTP
folate (low folate has been shown to cause depression)

I was just reading up on the boards here about what I missed while on my summer break. And I saw a post of yours, Kimmy, that you are in "pain management". Drugs can cause depression, and if you are on opiates orally, they can depress the pituitary axis and change hormone ratios. Some drugs deplete nutrients just by their nature. If you want to PM me or email me for privacy I can look at that for you.

Eating carbs can affect insulin levels. About 1/4 of people in this country, can eat carbs/sugar and show no negative metabolic effects and remain slim.
But most others gain weight, and become insulin resistant and eventually may develop Type II diabetes.

There is some evidence that what you crave you are intolerant of. There is a very good doctor with a book and online site that explains this. I really think she is the closest to the truth I have seen yet.
Dr. Kittley (Jensen) at www.obesitysanswer.com
Her elimination diet reveals if you are intolerant to something, and if it is controlling your health. I have her book too.

The brain uses glucose only for energy. So carbs (high glycemic carbs) and sugar give instant gratification. The supplement inositol helps with metabolizing carbs in the brain-- it helps insulin. So Dr. Kittley suggests it in addition to the amino acid taurine to help with cravings.

So your seemingly simple question, is not so simple after all!

I am just starting tryptophan myself, and hope to find some good effects in this same area of appetite control. (serotonin is involved with appetite and some diet drugs were designed for this effect --Redux and Meridia. Unfortunately they affect heart valves and pulmonary artery blood pressure so have been discarded).