Anorexia nervosa is a serious eating disorder characterized by severe food restriction and an intense fear of gaining weight. This condition often leads to a significantly low body weight and can manifest in various physical complications. One common physical manifestation is amenorrhea, the cessation of menstruation. This article explores the physiological reasons behind this connection, explaining how the body’s systems respond to severe energy restriction.
Understanding Anorexia Nervosa and Amenorrhea
Anorexia nervosa is an eating disorder defined by specific criteria from the Diagnostic and Statistical Manual of Mental Disorders (DSM-5). These include persistent restriction of energy intake, resulting in a significantly low body weight. Individuals also exhibit an intense fear of gaining weight, even when underweight, and experience a distorted perception of their body weight or shape.
Amenorrhea refers to the absence of menstruation. In anorexia nervosa, it typically presents as secondary amenorrhea, the cessation of periods for three or more consecutive months in someone who previously had regular cycles. This differs from primary amenorrhea, which describes the absence of menstruation by age 15. While amenorrhea was previously a diagnostic criterion for anorexia nervosa, it was removed in the DSM-5, although it remains a frequent physical consequence of the disorder.
The Body’s Hormonal Adaptation to Energy Deprivation
Severe energy deficit and malnutrition in anorexia nervosa trigger a survival response. This adaptive mechanism prioritizes essential bodily functions over reproduction, leading to a cascade of hormonal changes. The primary impact occurs in the hypothalamus, a brain region regulating many bodily processes, including hormone production.
The hypothalamus responds to low energy availability by suppressing gonadotropin-releasing hormone (GnRH) production. GnRH stimulates the pituitary gland at the base of the brain. Reduced GnRH signaling diminishes the pituitary gland’s secretion of luteinizing hormone (LH) and follicle-stimulating hormone (FSH).
LH and FSH are necessary for ovarian function, including estrogen production and egg release. Insufficient LH and FSH levels mean ovaries are not adequately stimulated, producing very little estrogen. This reduction prevents the uterine lining from thickening, a necessary step for menstruation, ultimately leading to amenorrhea.
Other hormones also play a role in this complex physiological response. Leptin, a hormone produced by fat cells, signals the brain about the body’s energy stores. In anorexia nervosa, low body fat leads to reduced leptin levels, signaling to the hypothalamus that energy reserves are too low to support reproduction.
Conversely, ghrelin, an appetite-stimulating hormone, is often elevated. This dysregulation of leptin and ghrelin further contributes to the brain’s perception of famine, reinforcing the suppression of the reproductive axis. The body conserves energy by shutting down non-essential functions like menstruation, perceiving it as a luxury it cannot afford during severe caloric restriction.
Reversing Amenorrhea and Restoring Health
Restoring menstrual function in anorexia nervosa primarily requires nutritional rehabilitation and sustained weight restoration. When the body receives consistent, adequate energy, it perceives the state of famine has ended. This allows the hypothalamus to gradually resume GnRH production, which leads to the restoration of LH and FSH secretion from the pituitary gland.
As LH and FSH levels normalize, the ovaries are once again stimulated to produce sufficient estrogen, enabling the menstrual cycle to return. This process of hormonal rebalancing and the return of menstruation can take time, even after a healthy body weight is achieved. Some sources suggest menstruation may resume once 90% of ideal body weight is reached, though this can vary.
Comprehensive treatment for anorexia nervosa addresses both physical and psychological aspects. Nutritional guidance, often starting with a gradual increase in caloric intake to prevent refeeding syndrome, is a core component. This holistic approach supports the body in rebuilding energy reserves and hormonal balance, leading to the restoration of menstrual cycles and overall health.