Like most things in life, exercise is good for you — in moderation. Exercise can help you control your weight, a beneficial thing since being overweight or obese can disrupt your menstrual cycle and keep you from ovulating. But excessive exercise can also interfere with your menstrual cycle by stopping ovulation if you lose large amounts of weight. To produce hormones that affect ovulation, you need a normal percentage of body fat; too much or too little can interfere with ovulation.
Causes of Anovulation
Ovulation, the release of a mature, ready-to-be-fertilized egg from a follicle in the female ovary, occurs once a month. If you don't ovulate, you have anovulatory cycles. You may have menstrual bleeding, but it might occur irregularly. Hormones such as the dominant female hormone estrogen play a crucial role in the selection and maturation of an egg. Anything that disrupts the normal flow of hormones will prevent ovulation. Both overweight and underweight can affect ovulation; if increased exercise affects your weight, it can affect ovulation.
Overweight and Ovulation
A study conducted by the Harvard Medical School and Harvard Pilgrim Health Care and reported in the March 2002 issue of "Epidemiology" found that infertility caused by failure to ovulation was associated with being overweight in 25 percent of cases. Because fat cells make estrogen, women with excess fat cell often have excess estrogen production, which interferes with ovulation. In an Australian study reported in the April 1999 "Journal of Clinical Endocrinology and Metabolism," researchers found that anovulatory overweight women who lost weight steadily but not rapidly over a six-month period through a diet and exercise program were more likely to start ovulating. Exercise decreases insulin resistance, a condition that can lead to both weight gain and diabetes over time.
Exercise and Underweight
Around 12 percent of women who have anovulatory cycle are underweight, according to the Harvard Medical School researchers in the March 2002 issue of "Epidemiology." Researchers in this study concluded that more overweight women who don't exercise enough are anovulatory than women who are underweight and who exercise too strenuously. Women need a minimum of 17 percent body fat to ovulate, reproductive endocrinologist Spencer Richlin reports on Baby Center. If you fall into the underweight category after increasing your exercise level, you may stop ovulating. Cutting back on your exercise routine and increasing your weight slightly may restart normal menstrual cycles and ovulation, Richlin advises.
Considerations
Keeping your weight in proper balance helps ensure that you ovulate each month. Excessive exercise can interfere with ovulation if you're too thin, but could help if you're overweight. Irregular menstrual cycles are a sign that you may not be ovulating; estrogen can build up the uterine lining, but if you produce too much or too little estrogen, abnormal hormone levels may prevent ovulation. The uterine lining will eventually break down as what appears to be menstrual bleeding, but you never ovulated.
References
- American Family Physician; Insulin Resistance Syndrome; Rao Goutham, M.D. ,et al.; March 2001
- BabyCenter;I'm Underweight and Have Low Body Fat. Will This Affect my Ability to Get Pregnant?; Spencer Richlin, M.D.
- "Journal of Clinical Endocrinology an Metabolism"; Restoration of Reproductive Potential by Lifestyle Modification in Obese Polycystic Ovary Syndrome: Role of Insulin Sensitivity and Luteinizing Hormone; M. Huber-Buchholz, et al.; April 1999
- "Epidemiology"; Physical Activity, Body Mass Index, and Ovulatory Disorder Infertility; J. Rich-Edwards, et al.; March 2002
- Advanced Fertility Center of Chicago: Anovulation
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