Ever wonder why marijuana smokers get the munchies? So did a team of scientists at Sanofi Recherche lab in Montpelier, France. Fifteen years ago they began investigating marijuana’s effects on the brain, including the well-known fact that cannabis makes users hungry. “We set out to try and create an anti-marijuana,” a drug that could suppress appetite by blocking the same switch in the brain activated by cannabis, says Gérard Le Fur, senior executive vice-president and board member at newly merged French pharmaceutical giant Sanofi-Aventis.

Acomplia diet pill  is the first in a new class of compounds under development to block receptors found in the brain and in fat tissue known as cannabinoid type 1 (CB1). These receptors control hunger and tobacco addiction. Chronic overeating and smoking sends them into overdrive. Blocking the CB1 receptors dramatically reduces such cravings. Results of a two-year clinical trial in the U.S. showed patients given Acomplia lost an average of 19 pounds, compared with five pounds for patients given a placebo. Those on Acomplia also reported higher levels of HDL, the good cholesterol, lower levels of triglycerides, and improved sensitivity to insulin. All are important in keeping heart disease at bay. “This could be a paradigm-shifting drug,” says Dr. Louis J. Aronne, president of the North American Society for the Study of Obesity.

The medicine is approved in 42 countries and is sold in 20 as a treatment for obesity and overweight patients with associated heart risk factors, the company said.

The June 13 decision suggested Zimulti won’t win the FDA’s backing after three patients committed suicide in medical trials. European Union regulators said this month that they will review the medicine for psychiatric side effects, and Sanofi said today it submitted more data to the London-based European Medicines Agency.