research doctors in humans. Sero-
tonin, Wurtman says, "provides the brain with telltale information on
the body's nutritional state. This information then helps the brain de-
cide what and when to eat next, and whether to be sleepy or responsive
to the environment."
About half of all obese people are "carbohydrate cravers," and Wurt-
man believes that most of them suffer from a short circuit somewhere
in their serotonin-producing systems. Indeed, the drug d-fenfluramine,
which...