Birth Control Pills Not Linked to Weight Gain

Women have long complained that popping birth control pills makes them pack on the pounds, but according to a recent study published in the journal of Human Reproduction, there is no correlation found between taking the pill and gaining weight, at least in monkeys.

Scientists from the Oregon National Primate Research Study Center gave oral contraceptives to rhesus macaque monkeys for eight months. Rhesus monkeys have reproductive systems that are nearly identical to those of humans.

The scientists monitored the monkeys' weight, body fat, food intake, activity levels and lean muscle mass. They found that the monkeys originally classified as "obese" lost 8.5 percent of their weight and 12 percent of body fat during the eight-month period because of a spike in metabolism.

The monkeys originally classified as "normal" maintained a steady weight and body fat throughout the study.

Although this most recent study was done on animals, there is a body of evidence that going on the pill does not result in weight gain. "Birth control pills do not make women fat," said Dr. Laura Corio, AOL's women's health expert. "Studies have shown that BMI, percentage of water, percentage of fat and waist-hip ratio did not increase with six cycles of birth control pills. In fact, 20 percent of women lost weight."

Many women doubt the data, saying controlled factors like diet and activity in the study do not mirror the everyday life of women; therefore the study does not provide accurate, real-world findings.

Dr. Lisa Perriera, an assistant professor in obstetrics and gynecology at University Hospitals Case Medical Center, agreed that there is no hard evidence showing the pill causes lasting and significant weight gain in women.

"This has been controversial for some time, and when I see patients, one of their big concerns is weight gain," she told AOL Health. "Birth control pills usually only cause a temporary, maybe five-pound weight gain having to do with bloating. It's real, but it usually goes away for most women taking the pill. It's just their body adjusting to being on new medication."

Performing a similar test on humans would be nearly impossible, Parriera said, because you cannot control a person's diet and exercise as easily.

To learn more about this study and birth control options, visit AOL Health.