Think clenbuterol and Alli are the only weight-loss pills that work? Ritalin (methylphenidate) is used to treat attention deficit disorder (ADD), narcolepsy (daytime sleepiness) and chronic fatigue syndrome.

It is a central nervous system stimulant that works by increasing dopamine levels in the brain. Dopamine is part of the body’s reward system that promotes feelings of well-being. Ritalin improves focus and energy levels and has a calming effect in people with ADD. It may also decrease appetite.

Canadian scientists found that people ate less food after receiving a single dose of Ritalin before eating at an all-you-can-eat buffet. They ate 11 percent fewer calories and 17 percent less fat. The researchers speculated that increased dopamine levels induced satiety (feeling of fullness) and reduced the craving for food.

The study involved a single dose of the drug administered to only 14 people, so it is too early to speculate about its long-term effects on weight loss. Weight-loss drugs undergo extreme scrutiny before they can be approved by the Food and Drug Administration (FDA).

They must demonstrate long-term effectiveness and safety (12 months) in well-controlled clinical studies and show minimal rebound weight gain for 12 months after people stop taking the drug. [sources: FitnessRX, The New York Times]