Top things to know:
- Concern about weight gain with birth control use is common and may keep some people from using it
- For a minority of people, hormonal birth control likely does cause weight gain
- For most people the combined hormonal pill, patch, and ring do not appear to cause weight gain and the hormonal IUD likely doesn’t cause weight gain
- The implant and the shot may contribute to weight gain in some people
Birth control and weight
A common belief people have about hormonal birth control is that it will cause weight gain (1-3). Some people may gain weight while using hormonal birth control, while others may experience bloating or changes in body composition (the amount and distribution of body fat) which could make them feel like they’re gaining weight. Concern about side effects like weight gain keeps some people from using hormonal birth control (4). People who report gaining weight while using hormonal birth control (such as the pill and the shot) are more likely to stop using it (5-7).
It’s important to note that what is considered to be an ideal weight or body type is impacted by social and cultural beliefs that are continually changing.
Unfortunately in some cultures, there is harmful pressure to conform to standards that may not be realistic. Even scientific measures such as body mass index (BMI) cannot adequately classify who is healthy or not. As it relates to birth control, some people may fear weight gain, some may desire it, and others may not consider it important at all.
Changes in hormone levels during puberty and menopause can impact body composition. Starting from puberty, estrogen causes body fat to be deposited on the chest, thighs, hips and butt (8). The hormonal changes that occur during and after menopause cause an increase in body fat, particularly around the abdomen (8,9). Some people experience an increase in weight around menopause, but this is believed to be related to aging more so than hormonal changes (8,9). Hormones also likely impact food intake over the menstrual cycle. Food intake decreases during the follicular phase (the first half of the cycle when estrogen is the dominant hormone) until ovulation (release of an egg from the ovary), then increases during the luteal phase (the second half of the cycle when progesterone is dominant) (8).
What your healthcare provider might say
Combined hormonal contraceptives are birth control methods that contain two hormones (estrogen and progestin) and include most pills, the patch, the ring, and some shots. Progestin-only contraceptives contain just a form of progestin hormone and include the implant, most intrauterine devices (IUDs), a shot, and certain pills.
There is not enough evidence to say that combined hormonal contraceptives cause weight changes, but if they do, the change in weight is likely small (10). In people using progestin-only contraceptives, most studies do not show an increase in weight or body fat, but some do show a small increase (11). Some people will gain weight on birth control, and some people may be more prone to weight gain than others.
Hormonal contraceptives have a number of uses in addition to protection from unwanted pregnancy. They are also used to treat or reduce symptoms of PCOS, endometriosis, heavy, irregular, or painful periods, and anemia. Fear of gaining weight may keep someone from starting birth control, or could lead to them using it incorrectly or inconsistently, or could cause them to stop using it altogether. This could leave someone without effective protection from unwanted pregnancy or without treatment for a condition. Talking to a healthcare provider can help you consider the possible risks and benefits of taking hormonal birth control.
Here’s why it’s tricky
Even though many people believe birth control causes weight gain, the research is not so clear cut. People generally tend to gain weight over time and weight fluctuates depending on when it’s measured. Most people gain weight from young adulthood to middle age, with an average weight gain of 0.52 kg (1.15 lbs) each year (12). There are daily, weekly, monthly, and seasonal patterns to weight. Two very small studies have shown that people weigh less in the morning than the evening (13,14). One study showed that weight had a pattern of increasing from Friday to Monday and decreasing from Monday to Friday (15). And adults in the U.S. tend to gain weight around the fall and winter holidays (16).
A study of people using birth control pills who were weighed every day for four months, showed that pill users gained about 0.2 kg (0.44 lbs) over the first 3 weeks of a pill pack and then lost the same amount during the placebo (withdrawal bleeding) week (17). Their weight did not change from the beginning to the end of the four-month study.
The copper IUD (e.g. Paragard, Mona Lisa, T-safe) does not contain any hormones, so there is no direct way that it would affect weight. Copper IUD users still gain weight in long-term studies though, just like people who aren’t using any contraception will gain weight with time and age. One study showed that long-term copper IUD users steadily gained weight—on average 4.0 kg (8.8 lbs) over 7 years (18). Copper IUD users are often used as the comparison group in studies looking at weight gain with various hormonal birth control methods. One group will use a hormonal birth control and one group will have the copper IUD, and typically both groups gain weight over time.
So while it may appear as though someone using a hormonal birth control has gained weight at the end of a study, it may not be any different than what they would have gained if they were using a non-hormonal method (such as a the copper IUD), or nothing at all.
Most adults are gaining weight and have normal patterns of weight gain and loss, but concern about gaining weight keeps people from starting birth control and makes people stop taking it. The issue of weight gain and birth control is not straightforward, and study results can often be unclear or contradictory. It’s possible that longer studies with more people are needed to fully understand the impact of hormonal birth control on weight.
Here’s what the research says about each birth control type
Progestin-only contraceptives and weight gain
The implant and the shot may contribute to weight gain in some people, but the hormonal IUD likely doesn’t cause weight gain.
Implant (e.g. Nexplanon):
It’s unclear whether the implant contributes to weight gain. One study showed that after using the implant for a year, users had gained 0.1 kg (0.22 lbs), which was similar to the weight gained by people using the copper IUD (19). The same study showed that there was no difference in the amount of body fat of implant users compared to copper IUD users after one year (19). Another study showed that implant users gained 2.1 kg (4.6 lbs) after a year of use, which was more than the people using the copper IUD in the study, but this difference in weight was only seen when users of all races were looked at together (20). When the researchers separated participants into two groups based on race (implant users who were black and implant users who were white or any other race), there was no difference in weight gain between implant and copper IUD users (20).
More research is needed to determine whether weight gain is associated with using the implant.
Hormonal IUD (e.g. Mirena, Liletta):
The hormonal IUD appears to not cause weight gain, but could possibly result in an increase in body fat. Several studies show that people who used the hormonal IUD for one year gained between 0.5 kg (1.1 lbs) and 2.9 kg (6.4 lbs), which was the same as the weight gained by copper IUD users (19-22).
One of these studies measured the change in weight of people who had been using the hormonal IUD for 10 years. After 10 years of continuous use, hormonal IUD users had gained an average of 4.0 kg (8.8 lbs), which was no different than the amount of weight gained by people who had been using the copper IUD for 10 years (21).
Looking at changes in body composition with hormonal IUD use is tricky. One study showed that there was no increase in the amount of body fat after a year of hormonal IUD use (19), while another study did find an increase in body fat percentage (22).
There are other hormonal IUDs, such as Kyleena, Jaydess, or Skyla, which have lower doses of progestin than Mirena or Liletta, but changes in weight on these particular types of IUD have not been well studied.
The shot (e.g. Depo-Provera):
Some studies have shown that people using the shot gain weight and others show no change in weight attributed to the shot. After using the shot for a year, users gained between 1.3 kg (2.9 lbs) and 2.2 kg (4.9 lbs), which was more than the weight gained by people using the copper IUD in some studies (20,21), but similar to the weight gained by copper IUD users in other studies (23,24).
Even studies that measured changes in weight for people using the shot for longer periods of time give conflicting results. In one study, shot users gained 6.5 kg (14.3 lbs) after 10 years, which was more than the weight gained by copper IUD users (21), but in another study, shot users gained 9.5 kg (20.9 lbs) over the 10-year period, which was the same as the weight gained by copper IUD users (25).
After 12 months of using the shot, one study showed an increase in overall body fat—particularly around the abdomen (23), but another small study showed no difference in body fat compared to copper IUD users (24).
But averages don’t tell the whole story. In one study that showed that the users of the shot did gain more weight on average than copper IUD users, this difference went away when researchers separated the research participants into two groups based on race (users of the shot who were black and users of the shot who were white or any other race) (20). In this study, black study participants were more likely to gain weight regardless of the birth control method (20). In another study, even though the average weight gains didn’t differ between groups, 4 out of 10 users of the shot had a large weight gain (an average of 4.6 kg or 10 lbs) and had an increase in abdominal fat, which didn’t happen in the copper IUD users (24).
Combined hormonal contraceptives
Research shows that the combined pill, patch, and ring do not appear to cause weight gain.
The pill (various brands):
After using the pill for six months, research participants in two studies did not gain any more weight than the people who weren’t using any kind of birth control (26,27), gaining 0.88 kg (1.94 lbs) on average (26). Pill users also did not have changes in body fat after six months (27) or a year (28). Among pill users, 10 out of 100 gained more than 7% of their body weight in one year of use, and 5 out of 100 lost more than 7% of their body weight (29).
The patch (e.g. Xulane):
After one year of patch use, people gained an average of 0.4 kg (0.88 lbs) (30,31), which was the same amount gained by pill users (31).
The ring (e.g. Nuvaring):
After a year, people using the ring gained 0.4 kg (0.88 lbs), which was the same as the amount of weight gained by people using the pill (28). There was also no difference in body fat among Nuvaring users after a year (28). For ring users, 8 out of 100 people gained more than 7% of their body weight after a year, and 7 out of 100 people lost more than 7% of their body weight (29).
It’s important to remember that these numbers are just averages. Some people in these studies gain weight and some lose weight, and the amount of weight differs from person-to-person. Some people may be more prone to gaining weight on birth control than others.
More research is needed to fully understand how and why different types of birth control may contribute to weight gain in some people, but not others.
Using Clue to track a new birth control method, along with weight and other symptoms (like whether you feel bloated), can help you figure out if things are changing and whether they are related to your birth control.