Our ancestors struggled to get enough calories just to stay alive. 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 many women, one question that comes up every so often is whether contraception is making weight management harder. Anxiety is contagious, which makes scary stories particularly 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.
For starters, it is important to keep this in mind: No matter what beauty ideals we may absorb from Hollywood and glamour, normal healthy women gain weight during the fertile years with or without contraception. At age 13, many girls are menstruating and some have reached their adult height, but the average weight is 100 pounds. By age 20, most have filled out, and American females 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 gaining weight, regardless of any effects from contraception. Consequently, in all trials of contraceptives, some women complain of weight gain, and so virtually all contraceptives list it as a possible side effect. Only after the fact, as data accumulate, are researchers able to tease apart normal gain from possible effects of contraceptive hormones.
Pregnancy and childbearing have such huge effects on our bodies that (barring certain medical conditions) the most significant health question related to any contraceptive is -- how well does it work? 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 percent, and abstinence commitments may cut that 85 percent 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 contraceptives have little effect on weight -- with a few very important exceptions. Here is the lay of the land.
IUDs -- The copper IUD is in the top tier for efficacy (99-plus percent) and at the same time is completely non-hormonal. 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. Hormone IUDs boost contraceptive effectiveness and may decrease menstrual symptoms. When it comes to weight, though, the difference appears small and inconsistent. One widely-publicized study found modest weight loss for women on both kinds of IUD but the effects were minimal, so don't assume either IUD will prevent normal weight changes.
Implants -- Like IUDs, implants are top-tier (99-plus percent effective). Unfortunately, information about implants and weight is lacking controlled research. In clinical trials and an online side-effect summary (not controlled research) five percent of women complained of weight gain, which is right around the rate found when a contraceptive has no significant effect on weight.
Depo/Shot -- Depo-Provera, also known as the shot, (94 percent effective) is where things get complicated when it comes to contraceptives and weight. When compared to IUD users, women using Depo-Provera gained an extra pound a year on average. But some women's bodies react quite differently, with weight gain that over time is unhealthy. It now appears that any woman who gains 5 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 percent effective) cause weight gain. But guess what? The best controlled studies, taken together, find that the effect of today's 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 percent effective), the primary weight question is going to be unintended pregnancy. With an annual failure rate of 1 in 8, a woman using a barrier method needs to be prepared for the eventuality of either an abortion or an unplanned child.
Natural Family Planning/Abstinence -- Like barrier methods, the primary weight question related to NFP (76 percent) or abstinence commitment is the likelihood of an unintended pregnancy -- only more so. Proponents like to say that abstinence is 100 percent effective. So are diets. In reality, abstinence education and virginity pledges have little measureable effect on STD or pregnancy rates. Plan B or ella can reduce pregnancy risk when an abstinence commitment fails, and has no effect on weight.
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.
 Trussell J. Contraceptive Efficacy. In Hatcher RA, Trussell J, Nelson AL, Cates W, Kowal D, Policar M. Contraceptive Techology: Twentieth Revised Edition. New York NY: Ardent Media, 2011.
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