A study by OHSU researchers may contradict what you thought you knew about "the pill." It indicates birth control pills no not lead to weight gain. Instead, it may help overweight women drop a few pounds. Doctor Allison Edelman says her team studied Rhesus Macaque monkeys; keeping their diets and activity levels the same while they were on "the pill." the normal weight monkeys stayed the same. Edelman says weight gain is one of the top reasons women decide to stop taking medications; but the study suggests it's more likely women are gaining weight because of changes in age or lifestyle. The doctor says the study was performed on monkeys because they're bodies are similar to humans, and it is extremely difficult to study weight changes in humans who have differing diet and exercise patterns.