CORVALLIS, Ore. — An Oregon State University researcher says weight loss supplements don't work.
Melinda Manore, professor of nutrition and exercise sciences at the university, reviewed the evidence surrounding hundreds of weight loss supplements and found no credible evidence that any single product results in significant weight loss. Many have detrimental health benefits, she reported.
The weight loss supplement industry rakes in about $2.4 billion a year in the United States.
The study, "Dietary Supplements for Improving Body Composition and Reducing Body Weight: Where is the evidence?" is published online in the International Journal of Sport Nutrition and Exercise Metabolism.
She learned that a few products, including green tea, fiber and low-fat dairy supplements, can have a modest weight loss benefit of 3-4 pounds. But they were tested as part of reduced calorie diets.
“For most people, unless you alter your diet and get daily exercise, no supplement is going to have a big impact,” Manore said.
The supplements Manor examined fell into four categories:
chitosan that block absorption of fat or carbohydrates,
stimulants such as caffeine or ephedra that increase metabolism,
products such as conjugated linoleic acid that claim to change the body composition by decreasing fat, and
appetite suppressants such as soluble fibers.
Many products had no randomized clinical trials to hold up the claims. Many don't include exercise as part of the regimen.
No regimen for weight loss has replaced eating a balanced diet and regular exercise, she said.