US Pharm
. 2011;36(2):6. 

Portland, OR—Contrary to popular belief, researchers at the Oregon National Primate Research Center at Oregon Health & Science University have found that birth control pills do not contribute to weight gain. Due to many variables, issues surrounding weight may be hard to study in humans, so two groups of rhesus monkeys—half obese, half normal weight—were given oral contraceptives over an 8-month period. At the study’s conclusion, the normal group’s weight remained stable, whereas the obese group lost a significant amount of weight (8.5%) and percentage of body fat (12%). According to senior author Judy Cameron, PhD, “We realize that research in non-human primates cannot entirely dismiss the connection between contraceptives and weight gain in humans, but it strongly suggests that women should not be as worried as they previously were.” Concern about weight gain is a major reason why women may avoid or discontinue birth control pills. 

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