Does My Birth Control Make Me Fat?

When women start hormonal birth control, they are often worried about weight gain. We looked at the science and separated fact from fiction in regards to weight gain associated with the pill.

Women around the world use hormonal birth control, not just to prevent pregnancy but also to regulate their periods and control acne.

These hormonal interventions are effective in resolving many of these issues. However, they do come with a risk.

Birth control changes your body’s hormonal environment. Women often worry about whether birth control will make them gain weight.

Research is vague, as are the causes.

It is a problem that the current studies are contradictory. Some women report gaining or losing weight; both side effects are listed in product information.

Weight gain due to birth control can be a temporary side-effect caused by fluid retention, not fat. It usually subsides within 2 or 3 months. Remember that weight gain is common from early adulthood until middle age.

 

In a study of women who took birth control pills and were weighed daily for four months, it was found that the pill users gained 0.2 kg (0.44 pounds) in the first three weeks before losing the same amount the following week. The weight of those who took birth control pills did not change between the beginning and the end.

In studies examining weight gain or hormonal birth control, copper IUDs are often used as a standard. In most cases, the intervention group uses hormonal birth control and the control group has an IUD made of copper. Both groups gained weight regardless of the birth control method.

In one study, copper IUD users who had been using the contraceptive for seven years (but did not use hormones) gained weight steadily (average 4kg or 8.8lbs). Weight gain can be as common with hormonal contraception as it is without.

What causes temporary weight gain and why?

Water retention is a common side effect, especially when combined with synthetic estrogens, giving the appearance of gaining weight. Theoretically, hormonal contraceptives can cause weight gain but only by causing fluid retention.

Several women report changes to their appetites, which can lead to an increase in calorie intake and weight gain. There is no conclusive proof that birth control directly causes weight gain.

It is often impossible to conduct large-scale studies in order to disprove myths about birth control and obesity. Researchers would have to give birth control and placebos to two groups of women. This could lead to an increase in unwanted pregnancies.

The weight gain of each woman is highly variable, as they are all genetically unique, have different body fat percentages, and are hormonally distinct.

Even though further research will help us better understand the effects of hormonal birth control, it is unlikely that birth control pills or vaginal rings, or contraceptive skin patchs, on average, will affect weight.