Do Oral Contraceptives Cause Weight Gain?
Combined oral contraceptives (COCs) do not cause clinically significant weight gain, and available evidence does not support a causal relationship between COC use and weight changes. 1
Evidence for Combined Oral Contraceptives
The highest quality evidence comes from systematic reviews that demonstrate:
Placebo-controlled trials show no evidence supporting a causal association between combination oral contraceptives and weight change. 1 This represents the strongest level of evidence available, as these trials control for natural weight fluctuations over time.
Most women (52%) remain within 2 pounds of their starting weight during COC use, and 72% of women experience either no weight change or weight loss. 2 The mean weight change after four cycles of triphasic OC use was 0.0 pounds. 2
Daily weight measurements reveal only minor cyclic fluctuations during COC use—approximately 0.5 pounds rising during the first weeks of each cycle and falling by the same amount during the last few days. 2 These normal menstrual cycle variations may be incorrectly attributed to the contraceptive itself.
Body Composition Considerations
When examining body composition specifically in young women using low-dose COCs (30 μg ethinyl estradiol):
Overall, there is no significant change in body mass index, body fat percentage, body water percentage, or fat distribution after six cycles of use. 3
Among the subset of women who do gain weight (approximately 30%), the gain is due to fat accumulation rather than water retention, but this occurs at similar rates in non-users. 3 This suggests the weight gain is not causally related to COC use.
Evidence for Progestin-Only Methods
The picture differs substantially for progestin-only contraceptives, particularly DMPA (depot medroxyprogesterone acetate):
DMPA (Depo-Provera)
DMPA is associated with weight gain in a subset of users, with studies showing weight gain status at 6 months is a strong predictor of future excessive weight gain with ongoing use. 4 However, weight gain does not occur in all patients. 4
Adolescents using DMPA show greater increases in body fat percentage (mean difference 11.00%; 95% CI 2.64 to 19.36) and greater decreases in lean body mass compared to those using no hormonal method. 5
The proportion of women gaining >3 kg/year is higher with DMPA compared to other hormonal contraceptives. 6
Adolescents with obesity who use DMPA appear to be at higher risk for weight gain compared to normal-weight DMPA users, normal-weight non-users, and obese COC users. 7
Other Progestin-Only Methods
Hormonal IUDs may affect body composition, with a 2.5% increase in body fat mass and a 1.4% decrease in lean body mass compared to non-hormonal IUD users. 7 However, whether hormonal IUDs are truly weight-neutral requires additional investigation. 7
Most progestin-only contraceptive studies show mean weight gain less than 2 kg up to 12 months, usually similar to comparison groups using other contraceptives. 5
Clinical Counseling Approach
Patients should be counseled that weight gain with COCs is a misperception and that concern about weight should not deter use of this highly effective contraceptive method. 2
For patients particularly concerned about weight:
Copper IUDs, barrier methods, and surgical sterilization are the most weight-neutral options. 7
Women with obesity are generally not more likely to gain weight with COCs, vaginal rings, IUDs, or implants than their normal-weight peers (with the exception of DMPA in adolescents). 7
Special Considerations for DMPA
When prescribing DMPA, specific counseling is warranted:
Inform patients that weight gain is a possible adverse effect, but emphasize that it does not occur in all patients. 4
Monitor weight at 6 months, as early weight gain predicts future excessive weight gain with continued use. 4
Consider alternative methods for adolescents with obesity who are at higher risk for weight gain with DMPA. 7
Common Pitfalls to Avoid
Do not attribute normal age-related weight gain (approximately 300 g/year or 0.1 kg/m² annually) to contraceptive use. 6
Recognize that cyclic weight fluctuations of 0.5 pounds during the menstrual cycle are normal and not caused by the contraceptive. 2
Avoid discontinuing effective contraception based on weight concerns without first reviewing the evidence with the patient. 1