Most weight loss supplements are not effective

An Oregon State University researcher has reviewed the body of evidence around weight loss supplements and has come with bad news for those trying to find a magic pill to lose weight and keep it off - it doesn't exist.

Melinda Manore reviewed the evidence surrounding hundreds of weight loss supplements, a $2.4 billion industry in the United States, and said no research evidence exists that any single product results in significant weight loss - and many have detrimental health benefits.
 
The study is online in the International Journal of Sport Nutrition and Exercise Metabolism.

A few products, including green tea, fiber and low-fat dairy supplements, can have a modest weight loss benefit of 3-4 pounds (2 kilos), but it is important to know that most of these supplements were tested as part of a reduced calorie diet.

''For most people, unless you alter your diet and get daily exercise, no supplement is going to have a big impact,'' Manore said.

Manore looked at supplements that fell into four categories: products such as 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.

She found that many products had no randomised clinical trials examining their effectiveness, and most of the research studies did not include exercise. Most of the products showed less than a two-pound weight loss benefit compared to the placebo groups.