Although weight gain is the most commonly reported side effect of the birth control pill, studies still have yet to prove that this is a causal relationship. However, we can definitely learn more about this trend by inspecting the mechanism of action of birth control pills in more detail.

How the Pills Work

To start to understand birth control’s association with weight gain, let’s first understand exactly how pills work. The pill releases hormones (estrogen and progestin which is a synthetic form of progesterone) into our bodies. These hormones have three main effects.

1. Combinations of estrogen and progestin prevent the ovaries from forming follicles and releasing eggs. (Without eggs, there is no possibility of pregnancy.)
2. Progestin thins the lining of the uterus to create an unfavorable environment for pregnancy.
3. Progestin thickens the mucus from the cervix, inhibiting sperm from swimming into the uterus to potentially fertilize an egg.

What effects do estrogen and progesterone have on the body?

Weight gain is due to consuming more calories than you expend through your exercise, breathing, and resting metabolic activity. More specifically, weight gain is caused by an increase in fat deposition, fluid retention, and/or muscle mass. Our physiologic circulating levels of estrogen and progesterone influence weight gain.

Estrogen affects our body’s fat storage — or in other words, how our body distributes fat to various body parts: our breasts, hips, and thighs, for example.

Subcutaneous fat — the kind of fat located in our breasts, hips, and thighs — contains a higher amount of estrogen receptors. These receptors are also known as alpha-adrenergic receptors, which block fat burning. Thus, those areas of our body might end up receiving a higher amount of fat distribution between puberty and menopause, when estrogen levels in our body are at their highest.

Estrogen also influences the production of corticosteroids in the kidneys, and thus affects the way our bodies maintain salt balance. Some studies report that women experience fluid retention (“bloating”) at the onset of their menstrual periods suggesting that fluid retention may not be a premenstrual symptom.

Weight gain doesn’t just come, however, in the form of bloating or increased levels of fat. Gaining muscle mass will also cause the numbers on the scale to go up. Anabolic steroids cause an increase in muscle mass.

But first, what is an anabolic hormone? An anabolic hormone is simply a hormone like the androgen, testosterone, that tells our bodies to grow more muscle.

As you may suspect, men tend to have more of these hormones. In general, women have circulating androgen hormones in smaller amounts. Scientists think that combination oral contraceptive pills are unlikely to cause weight gain in the form of muscle mass. However, the anabolic properties of combination hormonal contraceptives could result in increased food intake through a physiological effect on satiety and appetite.

Our body weight is further affected by other hormones such as: cortisol, an adrenal hormone that spikes when we’re stressed, or hormones produced by our thyroid (T3, T4, and calcitonin), which regulate metabolism, sleep, heart rate, and more. Insulin manages our blood sugar levels, leptin signals that we are full and should stop eating, and ghrelin stimulates appetite while increasing fat deposition.

There are numerous ways in which the various hormones in our body affect our body weight. The effects of birth control on weight gain are unproven in the medical literature even though some women and their clinicians are convinced that hormonal contraceptives cause weight gain. Appropriate counseling about typical weight gain on or off birth control may help reduce discontinuation of contraceptives due to perceptions of weight gain.

We must remember that healthy weight gain can come in many forms, such as building muscle mass from increased exercise and eating healthy, nutrient-rich foods. When considering weight-gain, try not to forget all the various hormones involved, rather than focusing on just the estrogen and progesterone found in the pill.

When To See A Doctor

If you are on the pill and experience any of the below side effects, you should speak to a doctor immediately:

• abdominal or stomach pain
• chest pain, shortness of breath, or both
• severe headaches
• eye problems such as blurred vision or loss of vision
• swelling or aching in the legs and thighs
• redness, swelling or pain in the calf or thighs

These conditions may suggest a more serious condition. The pill also has potential long-term effects such as cardiovascular problems or cancer risk.

The pill should not be taken by:

• women who are pregnant
• smokers over the age of 35 years
• anyone who has or has had thrombosis, a stroke, or a heart problem
• anyone with a close relative who had a blood clot before the age of 45 years
• people who have severe migraines, especially with an aura as the warning sign
• anyone who has or had had breast cancer or disease of the liver or gallbladder
• anyone who has had diabetes for at least 20 years or diabetes with complications

Before starting on the pill, it is advised that you thoroughly and completely discuss current medications and your medical history with a trained professional.

Talk to an Alpha Provider Today

If you are trying to gain weight and are considering birth control, there may be more options for you. With Alpha, you can consult with a doctor or nurse practitioner, be examined, and receive your treatment quickly and conveniently from your own home. Our doctors are experts in building custom treatment plans and are happy to walk you through any questions or concerns.

While not for everyone, birth control can be used for many purposes in addition to preventing pregnancy, including managing acne and decreasing menstruation pain. If you are concerned about or unsure of the possibilities of weight gain with birth control, you can be assured that with Alpha, you are always able to consult a professional without the long wait at a physician’s practice.

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