New research shows that women taking the birth control shot known as DMPA gained an average of 11 pounds over three years, but once they switched to nonhormonal contraception they began to lose the weight.

The study, which was published in the American Journal of Obstetrics and Gynecology, followed 703 women using depot medroxyprogesterone acetate (DPMA), oral contraception (desogestrel), or nonhormonal contraception (bilateral tubal ligation, condom or abstinence) for three years. DPMA users who switched to another method were followed for an additional two years. After analyzing the subjects' body weight and body mass, researchers found that DMPA users were more than twice as likely as the other women to become obese. "One concern is DMPA's link to increased abdominal fat, a known component of metabolic syndrome, which increases the risk of cardiovascular disease, stroke and diabetes," said lead author Abbey Berenson, M.D. The amount of weight gain on DMPA did slow down over time. Users of the shot who switched to non-hormonal control lost nearly four pounds over the next two years, but those who switched to oral contraception gained an additional four pounds. [EurekAlert]

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