The Real Truth About Weight Gain and Contraception
Come post-holiday season, many of us feel a little outside our comfort zone weight-wise, and we look at all kinds of factors: diet, exercise, sleep, supplements, meditation, hypnosis, psychotherapy, even surgery that might help us tip the scales a little less.
For many women, one question that inevitably comes up is whether contraception is making weight management harder. Modern Western women spend almost 40 years trying not to get pregnant. We have close to 400 fertile cycles out of which we want to get pregnant maybe once or twice or four times or not at all. That’s a lot of women spending a lot of time engaged in some kind of contraception, and consequently rumors abound about contraceptives and weight gain. What’s real?
The real scoop includes some bad news: Normal healthy women gain weight during their fertile years with or without contraception. At age 20, American women weigh on average 125-130 pounds. By age 55, the average is closer to 165, a total gain of 35 pounds. (Weight gain during the teen years is even more rapid, an average of 30 pounds in six years. Even long-distance runners 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 gaining weight, regardless of any effects from contraception. This is borne out in the fact that in all clinical trials of contraceptives some percentage of women complains of weight gain, and consequently, virtually all contraceptives subsequently list weight gain as a possible side-effect. Only after the fact, as data accumulate, are researchers able to tease apart normal weight gain from possible effects of contraceptive hormones.
This means that 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. The best research compares women with and without a given method over a span of months or years, but research like that can be hard to find. The kind of information that spreads the fastest and furthest is stories. Anxiety, in particular, is contagious, which makes scary stories particularly viral.
Sometimes we forget the big picture: Pregnancy and childbearing have such big effects on our bodies that with rare but noteworthy exceptions the most significant health question related to any contraceptive is--how well does it work? Many women don’t realize how often most contraceptives fail with “human factors” built into the equation. On the Pill, 1 in 12 women gets pregnant each year; relying on condoms alone, that rate is 1 in 8. (For no contraception the annual rate is 85%; 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 concerned about managing weight for health or lifestyle reasons, efficacy should be a primary consideration in choosing among contraceptive options.
Independent of the question of efficacy, the best research available suggests that most contraceptives have little effect on weight, with a few important exceptions. Here is the lay of the land.
IUD’s: The copper IUD is in the top category 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 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 IUDs, implants are in the top category of contraceptive efficacy (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 contraceptives and weight. 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, 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 40 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, life changes, and ... the holidays. 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 terminate 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/Abstinence: Like barrier methods, the primary weight question related to NFP (76% ) or abstinence commitment (58%) 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. Plan B or ella can reduce pregnancy risk when an abstinence commitment fails, and—just to stay on topic here--has no effect on weight. But in the end, the only hormone-free methods that are very effective are copper IUDs 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, and indeed they are a small part of the 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 as 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: mostly it 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.