Birth Control Can Negatively Affect  Muscle Gains in Young Women

Many young women who exercise regularly and use oral contraceptives (OCs) are not aware of the effects of hormones on their body composition. High-intensity workouts and weight-lifting exercises usually result in muscle gain. Taking potent hormones such as birth control pills could impair muscle response to standardized exercise.

A study published in The Journal of Strength and Conditioning Research compared the muscle growth of women on hormonal birth control and those who were not using hormonal contraception. The women were between the ages of 18-and 29 years and completed a 10-week total-body resistance training program designed to build muscle.

The authors of the study used hydrostatic weighing to determine body composition, and blood samples were taken before and after training to measure the hormones, dehydroepiandrosterone (DHEA), DHEA sulfate (DHEAS), IGF-1, and cortisol levels.

The authors reported that the group of women who were on hormonal birth control developed 40% less lean muscle mass than the women who were not taking hormonal birth control. Additionally, there were significant differences in lean mass gains depending on the type of progestin in hormonal contraceptives users. The more androgenic progestin used less muscle gain was found. Hormonal profiles at rest and post-workout showed that the women taking birth control had lower levels of anabolic hormones (DHEA, DHEAS, and IGF-1), but higher levels of cortisol.

Muscle growth is influenced by several hormones in the woman’s body. Testosterone and growth hormone cause muscle gain. In contrast, cortisol is a catabolic hormone, meaning it breaks muscle tissue down.

The authors of the study concluded that the diminished lean mass may be related to the effect of hormonal contraceptives on anabolic and catabolic hormone levels. Also, progestin present in hormonal contraceptives may bind to androgen receptors and inhibit its function.

Young women need to be informed of the side effects and hormonal changes caused by birth control. Although more research needs to be done in this area, safer alternatives to birth control need to be considered to achieve not only muscle-focused fitness goals but general health and wellbeing.

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