What is the relationship between amenorrhea (absence of menstruation) and weight loss?

From the Guidelines

Amenorrhea due to weight loss is a serious condition that requires prompt medical attention and weight restoration to a healthy BMI, typically above 18.5-19 kg/m², as it is crucial for preventing further bone mass loss and improving overall health outcomes 1. To address this, the following steps can be taken:

• Increase caloric intake gradually, aiming for 500-1000 extra calories per day to support weight gain and resumption of menses.
• Focus on nutrient-dense foods, including proteins, healthy fats, and complex carbohydrates, to optimize energy availability and support bone health.
• Consider working with a registered dietitian for a personalized meal plan to ensure adequate nutrition and energy intake.
• Reduce excessive exercise if present, as it can exacerbate energy deficiency and worsen amenorrhea.
• Aim for weight gain of 0.5-1 kg (1-2 lbs) per week, as significant improvements in bone health outcomes were observed in studies of amenorrhoeic anorexic female athletes who gained weight 1. It is essential to understand that amenorrhea from weight loss is the body's way of conserving energy when it perceives a threat to survival, and low body fat disrupts the hormonal balance necessary for menstruation. Restoring weight helps normalize hormone levels, particularly leptin, which is crucial for reproductive function. Persistent amenorrhea can lead to long-term health issues, including bone density loss, so addressing it promptly is essential for overall health. The relationship between amenorrhea and weight loss is complex, and the aetiology of bone loss among amenorrhoeic women includes energy deficiency-related factors and oestrogen deficiency, highlighting the importance of weight gain and resumption of menses in preventing further bone mass loss 1. Key findings from the 2014 female athlete triad coalition consensus statement suggest that weight gain and subsequent resumption of menses are key to preventing further loss of bone mass, with estimates indicating that amenorrhoeic women will lose approximately 2–3% of bone mass per year if the condition remains untreated 1.

From the Research

Relationship Between Amenorrhea and Weight Loss

• Amenorrhea, or the absence of menstruation, is often associated with weight loss, particularly in adolescents and women of reproductive age 2.
• Weight loss-related amenorrhea is defined as the reversible functional inhibition of the hypothalamic-pituitary-ovarian (HPO) axis associated with weight loss or low body weight 2.
• Studies have shown that women with moderate weight loss (10%-15% of ideal weight) may experience secondary or primary amenorrhea, which is usually reversible with weight gain, decreased exercise, or both 3.

Mechanisms and Effects

• The specific pathological mechanisms of weight loss-related amenorrhea have not yet been fully elucidated, but it is thought to be related to hypothalamic dysfunction, which affects the pituitary-ovary axis 2, 3.
• Weight loss-related amenorrhea can have adverse effects on female health, including reproduction, skeletal and cardiovascular systems, and mental health 2.
• Increased neuropeptide Y (NPY) pulsatility may have pathophysiological significance in weight loss-related hypothalamic amenorrhea 4.

Treatment and Recovery

• Lifestyle changes, such as weight gain and decreased exercise, and hormonal replacement therapy have been shown to alleviate the underlying causes of weight loss-related amenorrhea and lead to the recovery of menstruation 2, 3.
• Individualized treatments need to be optimized, and emerging or multidisciplinary therapeutic approaches need to be explored to recover normal menstruation and ovulation, eliminate the undesirable effects of prolonged hypoestrogenism, and alleviate psychological disorders 2.

Body Fat and Ovulation

• A minimum level of stored, easily mobilized energy, indicated by an index of fatness, is necessary for ovulation and menstrual cycles in the human female 5.
• Simple weight loss is associated with menstrual dysfunction when over 30% of body fat is lost, and women using oral contraceptives who lose minor degrees of weight or body fat are at risk for the development of secondary amenorrhea 6.