This years hottest weight-loss books are all about eating what you love and still losing weight. Fact or fiction? FITNESS reveals what's really possible.

...The Serotonin Power Diet
by Judith Wurtman, Ph.D., and Nina Frusztajer Marquls, M.D.

The Claim: Eating starchy or sweet snacks in the mid-morning and afternoon will decrease stress and help you lose weight.

The Science Behind It: Research shows that the body needs carbs to produce serotonin — the neurotransmitter that makes you feel happy. Elevated levels of it can also help curb your appetite.

Best Thing About It: You can eat marshmallows and graham crackers guilt-free.

Worst Thing About It: You might pig out.

Try It If: You crave carbs and sugar and have lots of self-control...