Does Metformin Make You Lose Weight?

Metformin, an oral medication approved for treating type 2 diabetes, helps regulate blood sugar in patients that do not require insulin. This medicine is associated with weight loss in people with certain health disorders or taking certain additional types of medication, according to an article published in the April 2002 issue of the "American Journal of Psychiatry." This does not necessarily mean metformin can make anyone else lose weight.

Function

Insulin resistance, one cause of type 2 diabetes, involves diminished ability of cells to respond to insulin's function of transporting glucose from the blood into tissue and muscle. With cells unable to accept this glucose, it builds up in the blood and leads to high blood sugar. Metformin improves cellular response to insulin. The medication is linked to weight loss in people with conditions characterized by insulin resistance other than type 2 diabetes, according to the "American Journal of Psychiatry" article. Metformin may induce weight loss in women with polycystic ovary syndrome, known as PCOS, and in obese men and women with hyperlipidemia.

Research

Drug manufacturers must conduct large clinical trials before the U.S. Food and Drug Administration approves pharmaceutical products, in order to determine effectiveness and incidence of side effects. Preapproval metformin research focused on people taking the drug for type 2 diabetes. In most preapproval studies on metformin, as detailed by eMedTV, participants taking the drug lost an average of 1.4 to 8.4 lbs., but the participants taking a placebo also lost weight. The difference in weight loss between the two groups was not statistically significant, making it difficult to know if taking metformin actually induces weight loss in people with type 2 diabetes.

Metformin and PCOS

Doctors are allowed to prescribe medication for so-called off-label uses, or uses not approved by the FDA, as long as the medication is legal. Although the FDA has only approved metformin for treating type 2 diabetes, doctors commonly prescribe it for women with PCOS. A study appearing in the "Journal of Clinical Endocrinology and Metabolism" in 2005, Vol. 90, No. 8, found that obese women taking PCOS experienced significant weight loss when taking either 1,500 or 2,550 mg metformin per day.

Metformin and Antipsychotic Drugs

Metformin may be beneficial for patients taking antipsychotic drugs, because those drugs are notorious for causing weight gain. The "American Journal of Psychiatry" study evaluated metformin as a treatment for weight gain in 19 children ages 10 to 18 years old taking various antipsychotic drugs. Over 12 weeks while taking metformin, the majority lost weight and experienced highly significant improvements in weight and body mass. Another study, this one published in the January 9-16, 2008 issue of the "Journal of the American Medical Association," focused on 128 adult patients with schizophrenia with weight gain due to medication. Metformin with no behavior changes was more effective for weight loss than lifestyle intervention by itself, while lifestyle intervention plus metformin had the best effects on weight loss.

No Weight Gain

In most clinical trials with metformin, participants with type 2 diabetes did not gain weight, according to eMedTV. This is noteworthy because many other medications for diabetes cause weight gain, of particular concern since being overweight is associated with type 2 diabetes, and many people with type 2 diabetes are already overweight.