The birth control method most consistently linked to weight gain is the Depo-Provera shot (DMPA). Combined oral contraceptives, often called “the pill,” have not been shown to cause meaningful weight gain in clinical trials. Other methods fall somewhere in between, with most hormonal options causing little to no measurable change for the average user.
That said, individual experiences vary widely. Here’s what the research actually shows for each type.
The Depo-Provera Shot: The Strongest Link
Depo-Provera stands apart from other contraceptives when it comes to weight gain. On average, users gain about 5.3 pounds (2.4 kg) while on the shot, but the range depends heavily on age. In one study, adolescents gained roughly 11.8 pounds (5.35 kg) compared to about 3.9 pounds (1.75 kg) for adults. That’s a significant difference, and it’s one reason the CDC specifically recommends monitoring weight over time for people using this method.
Starting weight matters too. A prospective study of adolescent girls found that those who were already in the obese BMI range at the time they started Depo-Provera gained significantly more weight than girls in the same weight category who started the pill or no method at all. Among girls who weren’t obese at baseline, the contraceptive method made no statistically significant difference. So if you’re considering the shot and already concerned about your weight, this is worth factoring in.
Combined Pills, Patches, and Rings
Despite their reputation, combination contraceptives (those containing both estrogen and a progestin) have not been shown to cause real weight gain. A Cochrane systematic review, the gold standard for evaluating medical evidence, looked at trials that compared combination methods against placebos or no treatment. The conclusion: no causal relationship between combination contraceptives and weight gain has been established, and no large effect is evident.
This applies regardless of which progestin the pill contains. You may have heard that newer formulations with drospirenone are more “weight-neutral” than older pills with levonorgestrel, but the available evidence doesn’t show a meaningful difference between them. Neither type causes significant weight gain compared to a placebo.
What combination methods can cause is temporary water retention. Estrogen shifts the body’s fluid regulation, lowering the threshold at which your body holds onto water and slightly increasing plasma volume. This can show up as a pound or two on the scale, especially in the first few months, but it’s fluid, not fat. It typically stabilizes and doesn’t progress over time.
Hormonal IUDs
Hormonal IUDs like Mirena and Kyleena release a progestin (levonorgestrel) directly into the uterus, so very little hormone reaches the rest of your body. The weight data reflects this: in a 12-month study, hormonal IUD users gained an average of about 2.3 pounds (1 kg), which was not statistically different from users of the copper (non-hormonal) IUD. After adjusting for age and race, the association between the hormonal IUD and weight change disappeared entirely.
In short, hormonal IUDs are one of the least likely hormonal methods to affect your weight.
The Implant (Nexplanon)
The implant sits in a gray zone. In one clinical trial, 15.3% of implant users reported perceived weight gain at three months, compared to 4.3% in the control group. That’s a real difference in how users felt, but when researchers measured actual weight changes over 12 months and adjusted for age and race, the implant did not show a statistically significant difference from other methods.
This gap between perceived and measured weight change is common across contraceptive research. It doesn’t mean your experience isn’t real, but it does suggest the implant’s effect on weight, if any, is modest for most users.
The Copper IUD (Paragard)
The copper IUD contains no hormones, so it’s often recommended as a weight-neutral option. But “weight-neutral” doesn’t mean your weight will stay frozen. In a large cohort study following nearly 1,700 copper IUD users over seven years, women gained an average of about 8.6 pounds. That gain had nothing to do with the IUD itself. It reflected normal weight changes during the reproductive years, the same gradual increase most adults experience over time regardless of contraception.
Why Progestins Can Affect Appetite
The reason Depo-Provera is the outlier comes down to dose. The shot delivers a large amount of progestin into your bloodstream every three months. Progestins can influence hunger signals in the brain by increasing the activity of appetite-stimulating pathways while suppressing appetite-reducing ones. In animal studies, progesterone administration increased food intake, body mass, and fat tissue. The appetite-stimulating signal in the brain roughly doubled, while the appetite-suppressing signal dropped to about a third of normal levels.
Methods that deliver progestin locally (like the hormonal IUD) or in lower systemic doses (like the implant or the pill) expose the brain to far less hormone, which is why their weight effects are minimal or undetectable. The dose reaching your bloodstream, not just the type of hormone, is what matters most.
Who Is Most Likely to Gain Weight
Not everyone on the same method will have the same experience. The research points to a few factors that increase the likelihood of noticeable weight gain on hormonal contraception:
- Age: Adolescents on Depo-Provera gain roughly three times as much weight as adults on the same method.
- Starting weight: People who are already at a higher BMI when they begin Depo-Provera tend to gain more than those at a lower starting weight.
- Method choice: The shot carries the highest risk. The pill, patch, ring, hormonal IUD, and implant carry little to no measurable risk for most users.
Race also appeared as a factor in some studies, with Black women showing slightly higher weight gain across multiple contraceptive types, but this association became statistically insignificant after adjusting for age and other variables. It likely reflects broader metabolic and socioeconomic factors rather than a different hormonal response.
Water Retention vs. Actual Fat Gain
It’s worth separating two different things that both show up on a scale. Estrogen-containing methods can cause mild fluid retention by increasing sodium reabsorption in the kidneys and shifting how your body manages plasma volume. Progesterone does something similar through a slightly different mechanism, expanding fluid in the bloodstream by keeping more protein in the vascular space. These effects are small, typically a few pounds at most, and they stabilize.
True fat gain, the kind seen with Depo-Provera in some users, involves increased appetite and actual changes in fat tissue. This distinction matters because fluid-related changes reverse quickly if you stop the method, while fat gain requires the same effort to lose as weight gained for any other reason. If you notice a jump of two to three pounds in the first month or two on a new pill, that’s almost certainly water. If you notice a steady upward trend over six months on the shot, the method itself may be contributing.