Do birth control pills cause weight gain? New research says no

Jan 19, 2011

According to research conducted at the Oregon National Primate Research Center at Oregon Health & Science University, the commonly held belief that oral contraceptives cause weight gain appears to be false. The results of the study are published online and will appear in next month's edition of the journal Human Reproduction.

"A simple Google search will reveal that contraceptives and the possibility that they may cause weight gain is a very highly debated topic," said Alison Edelman, M.D., a physician and researcher in the Department of Obstetrics and Gynecology at OHSU and lead author of the study.

"Issues surrounding weight are hard to study in humans, and the research thus far has been insufficient to demonstrate whether or not cause weight gain or loss. But this is an extremely important question as concern about weight gain is one of the main reasons why women may avoid or discontinue birth control, which in turn places them at greater risk for an unplanned pregnancy."

To conduct their research, scientists and physicians studied a group of rhesus macaque monkeys at the OHSU Oregon National Primate Research Center for almost a year. Rhesus monkeys were used in this study because their reproductive system is nearly identical to humans. However, unlike human studies, more variables can be controlled and measured – such as exact food intake - to provide more meaningful data.

At the beginning of the study, half the animals were obese and half were normal weight. During the eight-month treatment period, animals received doses of oral contraceptives, adjusted to the weight of the animals so that it mimicked dosage in humans. Researchers tracked weight, food intake, activity levels, body fat and lean muscle mass. At the study's conclusion, the normal weight group remained weight stable whereas the obese group lost a significant amount of weight (8.5%) and percent of body fat (12%) due to an increase in basal metabolic rate. No changes were seen in , activity or lean muscle mass for either group.

"This study suggests that worries about weight gain with pill use appear to be based more on fiction than on fact," said Judy Cameron, Ph.D., senior author of the paper and a researcher at the primate center.

"Additionally, there may be a differential affect depending on your starting weight – heavier individuals who keep their diet stable may see a weight loss with pill use. Most likely, the reason why this belief continues to exist is that the weight gain that seems to occur with age is being attributed to these medications. We realize that research in nonhuman primates cannot entirely dismiss the connection between contraceptives and in humans, but it strongly suggests that women should not be as worried as they previously were."

Explore further: India's meth addiction grows as criminals tap chemical hub

add to favorites email to friend print save as pdf

Related Stories

Diet alone will not likely lead to significant weight loss

Apr 13, 2010

Newly-published research by scientists at Oregon Health & Science University demonstrates that simply reducing caloric intake is not enough to promote significant weight loss. This appears to be due to a natural compensatory ...

Study shows why weight gain is inevitable

May 09, 2006

Denmark's National Exercise and Nutrition Council says it has found people cannot lose more than 5 percent to 10 percent of their weight through dieting.

Recommended for you

FDA to start regulating lab-developed tests

18 hours ago

(AP)—The Food and Drug Administration announced Thursday it will begin regulating laboratory-developed tests, a growing class of medical diagnostics that have never before been subject to federal oversight.

Determine patient preferences by means of conjoint analysis

Jul 29, 2014

The Conjoint Analysis (CA) method is in principle suitable to find out which preferences patients have regarding treatment goals. However, to widely use it in health economic evaluations, some (primarily methodological) issues ...

User comments : 1

Adjust slider to filter visible comments by rank

Display comments: newest first

rgwalther
not rated yet Jan 30, 2011
Not taking BC and engaging in sex... weight gain is certain though limited to 9+ months.