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The right weight: body fat, menarche and ovulation
Bailliere'S Clinical Obstetrics and Gynaecology
|September 1, 1990
Summary
Amenorrhea in women, including athletes, is often caused by hypothalamic dysfunction due to low body fat. This condition is typically reversible with weight gain or reduced exercise, highlighting body fat
Area of Science:
- Reproductive Endocrinology
- Human Physiology
Background:
- Secondary or primary amenorrhea affects women with significant weight loss (10-15% or anorexia nervosa's 30%).
- Amenorrhea is also prevalent in highly trained dancers and athletes, even with normal body weight, due to high muscle mass.
- This condition is generally reversible with weight restoration and/or reduced physical activity.
Purpose of the Study:
- To investigate the relationship between body fat percentage, weight loss, and amenorrhea in women.
- To establish target weights for evaluating and treating amenorrhea related to weight loss.
- To explore the mechanisms by which body fat influences reproductive cycles.
Main Methods:
- Review of existing evidence on weight loss, body composition, and menstrual function.
- Analysis of the hypothalamic-pituitary-ovary axis in amenorrheic individuals.
- Discussion of the role of body fat in estrogen production and metabolism.
Main Results:
- Hypothalamic dysfunction, not pituitary-ovary axis issues, causes amenorrhea in these cases, suggesting an adaptive response.
- A body fat percentage of 26-28% in mature women appears necessary for regular ovulatory cycles.
- Body fat influences reproductive ability through extragonadal estrogen production, estrogen metabolism, and sex hormone-binding globulin interactions.
Conclusions:
- Amenorrhea associated with weight loss or intense training is primarily due to hypothalamic dysfunction.
- Adequate body fat is crucial for maintaining regular ovulatory cycles in women.
- Understanding these mechanisms aids in the evaluation and treatment of amenorrhea.