Birth Control and Weight Gain: Is there a relationship?

Many women worry about birth control causing weight gain. Our ancestors struggled to get enough calories just to stay alive. But now, as we try to keep our weight in a healthy range, we look at all kinds of factors: diet, exercise, sleep, supplements, meditation, hypnosis, psychotherapy, prayer, or even surgery that might help us tip the scales a little less.

For a woman who is struggling to fend off excess weight, one question that comes up is whether birth control could be making weight management harder. The typical woman spends almost forty years trying to not get pregnant. That’s a lot of time to be putting stuff into our bodies–pills, rubber, spermacides, IUDs–and consequently rumors abound. Anxiety is contagious, which makes scary stories go viral. As a woman trying to figure out what is best for your body, it can be challenging to sort out reality from hype or haze.

Birth Control Weight Gain Vs. Ordinary Weight Gain

To figure out which contraceptive is best for your health, it is important to keep this in mind:  No matter what beauty ideals we may absorb from Hollywood and Glamour Magazine, normal healthy women gain some weight during the fertile years with or without birth control. Weight gain is a natural part of maturation. At age 13, many girls are menstruating and some have reached their adult height,  but the average weight is 100 pounds.  By age 20, they have filled out, and American women weigh on average 125-130 pounds. By age 55, the norm is closer to 165 before average weight then starts declining. (Even long distance runners and other highly active women tend to gain over time.)

The net-net is that any time a woman is contracepting is a time she is also likely to be on the upward-moving part of her personal lifetime weight curve, regardless of any effects from birth control. Consequently, in all clinical trials of contraceptives some women complain of weight gain, and so virtually all types of hormonal birth control list weight gain as a possible side effect. Only after the fact, as data accumulate, are researchers able to tease apart normal age-related changes from possible effects of contraceptive hormones.

Also, sometimes we forget the big picture: Pregnancy and childbearing have such huge effects on our bodies that (barring certain medical conditions) the most significant health question related to any birth control method is–how well does it work? Many people don’t realize how often most contraceptives fail with “human factors” built into the equation. On the Pill, one in eleven women gets pregnant each year; relying on condoms alone, that rate is almost one in six. (Without birth control the annual rate is more than eight in ten; abstinence commitments may cut that 85% rate by about half.) With a long acting method like an implant or IUD, the pregnancy rate drops to 1 in 500 or less. If you are trying to managing weight for health or lifestyle reasons, efficacy should be a primary consideration in choosing among contraceptive options.

Efficacy aside, the best research available suggests that most forms of birth control have little effect on weight gain, with a few very important exceptions. Here is the lay of the land.

Weight Gain and Birth Control Options

IUD’s – The copper IUD is in the top tier for efficacy (99%+) and at the same time is a completely non-hormonal method. This means that, despite some challenges in insertion and adjustment, it is the gold standard for women who want no artificial hormones. Its only effect on weight gain is through reducing unintended pregnancies. Hormonal IUDs boost contraceptive effectiveness (and also decrease menstrual symptoms) by releasing a mostly local micro-dose of a progestin, Levonorgestrel. When it comes to weight gain or loss, though, the difference appears minimal. One study showed slightly more gain in hormonal IUD than copper IUD users, but a longer study found that women with hormonal IUDs gained slightly less weight than women with no hormonal contraceptive. Other research reported modest weight loss for women on both kinds of IUD. Since the differences appear small and inconsistent, don’t assume either IUD will prevent normal weight changes.

Implants—Like IUD’s, implants are in the top tier of effective birth control (99%+). Unlike an IUD, an implant releases a systemic dose of hormone, which has both advantages and disadvantages. Unfortunately, information about implants and weight is lacking controlled research. In an online side-effect summary (not controlled research) five percent of women using an implant complained of weight gain, which is right around the rate found when a contraceptive has no significant effect on weight. One study monitored implant users for a year and found no change. Anecdotes include stories of both weight gain and, less often, loss. Such stories may not be good evidence, but they are a good reminder: even when the typical effect of a contraceptive is neutral it is important to listen to your own body.

Depo/Shot—Depo-Provera, also known as the Shot, (94% effective) is where things get complicated when it comes to birth control and weight gain. On average, users of Depo-Provera gained an extra pound a year when compared to IUD users. But the average doesn’t tell the whole story. Some women appear to gain a couple of pounds over many years of using Depo, which they find well worth trading for effective contraception and menstrual suppression that they have to think about only four times per year. Other women’s bodies react quite differently to injectible birth control, with weight gain that over time is unhealthy. Teenagers who are already heavy (who, incidentally, appear most at risk to develop obesity after pregnancy), may be particularly vulnerable. Fortunately, the difference shows up pretty quickly. It now appears that any woman who gains five percent of her body weight in the first six months on the Shot is at risk for ongoing, contraception-related weight gain and should consider another method.

Patch, Ring, Pill –It is widely believed by women and doctors alike that the Pill and related combination contraceptives (all around 91% effective) cause weight gain. But guess what? The best controlled studies, taken together, don’t find any such effect. Women on the Pill or Patch or Ring absolutely do gain weight over time; remember those pounds we tend to gain between adolescence and menopause? But carefully comparing women who use combination hormonal contraceptives and women who do not suggests the spurts of weight gain some women experience while on these methods are largely caused by other factors like aging, stress, health issues, and  life changes. The best data available to date suggest that the effect of the Pill, Patch or Ring is usually negligible and that women who respond by putting on pounds are roughly equaled by those who respond by dropping pounds.

Barrier Methods—For a barrier method like condoms or a diaphragm (82-88% effective), the primary weight question is going to be unintended pregnancy. With an annual failure rate of one in eight, a woman using a barrier method needs to be prepared for the eventuality of either an abortion or an unplanned child. Needless to say, a pregnancy, even one that is terminated, causes fluctuations in hormones. Fortunately, pregnancies can be identified earlier and earlier, and women who choose to end a problem pregnancy don’t go through the same level of hormonal and body changes that were characteristic a generation ago. However, a woman who feels strongly that she is not ready to have a child (or another child) is probably better off with a more effective method of contraception.

Natural Family Planning or Abstinence Commitment– Like barrier methods, the primary weight gain question related to NFP (76% effective) or abstinence commitment is the likelihood of an unintended pregnancy—only more so. Proponents like to say that abstinence is 100% effective. So are diets. The reality is that humans are imperfect, and sex and hunger are two of our most powerful drives. NFP requires not only monthly abstinence but a level of self monitoring and communication that is not feasible for most people. Abstinence education and virginity pledges have little measurable effect on STDs or sexual behavior. Eighty-eight percent of pledgers have sex before marriage. Plan B or ella can reduce pregnancy risk when an abstinence commitment fails, and has no effect on weight gain. But in the end, the only hormone-free methods that get rid of this risk cycle are copper IUD’s and nonreversible methods like tubal ligation or vasectomy.

For a woman who wants a child, hormonal changes and weight gain related to pregnancy are a small price to pay.  Indeed they are a small part of a larger price we gladly pay when we decide to have a baby. Surprisingly, except in women already prone to gain and retain weight, childbearing itself has little long term effect on body weight. Within a couple years after a pregnancy, most women tend to be back on a similar weight trajectory to their same age peers, with an average of an extra pound or so per child.

Women’s bodies respond differently to hormones, as we all know. Some of us have horrid periods and pregnancies. Some of us breeze through. Some of us barely gain a few pounds while incubating a baby; others gain a third or even half of our body weight. It is reasonable to assume that there are differences in how we respond to hormonal contraceptives as well, and every woman needs to listen to her own mind and body. All the same, it helps at times to remind ourselves of what is known—and to update our knowledge, since technology and research are constantly moving forward.

So, the bad news about contraception is this: mostly it isn’t the explanation for those frustrating extra pounds. You are likely to gain some weight over the next decade regardless. So am I. Throwing the Pill pack in the garbage or getting the IUD or implant pulled isn’t likely to be a magic bullet. The great news about contraception is this: “birth control weight gain” isn’t the explanation for those frustrating extra pounds. We really do have good options when it comes to managing our fertility, better options than most of us thought; better options than our mothers and grandmothers could even imagine.

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Read more:
A Brief History of Your Period and Why You Don’t Have to Have It
Picture a Technology Revolution. In Contraception. It’s Here.
Dramatic Drop In Teen Pregnancy Really a Technology Tipping Point
Pamper, Pamper, Pamper – Plus 9  Other Tips for Falling in Love With Your IUD
The Big Lie About Plan B – What You Really Should Be Telling Your Friends

Valerie Tarico is a psychologist and writer in Seattle, Washington.  She is the author of Trusting Doubt: A Former Evangelical Looks at Old Beliefs in a New Light and Deas and Other Imaginings, and the founder of www.WisdomCommons.org.  Her articles can be found at Awaypoint.Wordpress.com and videos on the psychology of religion at YouTube:AwayPoint.