How well do weight-loss drugs work?

Prescription weight-loss drugs that you can use for more than 12 weeks, called long-term use, lead to major weight loss compared with an inactive treatment that doesn't use medicine, called a placebo. The combination of weight-loss medicine and lifestyle changes leads to greater weight loss than do lifestyle changes alone.

Taking these drugs for a year can mean a loss of total body weight of 3% to 12% more than that lost with lifestyle changes alone. That may not seem like a lot. But losing 5% to 10% of your total weight and keeping it off can have important health benefits. For example, it can lower blood pressure, blood sugar levels and levels of fats in the blood called triglycerides.