Too Thin To Conceive

How Anorexia Impacts Fertility

By Kelly Burgess

Marlene Clark, a registered dietician who specializes in eating disorders at Cedars-Sinai Medical Center and co-author of Carrying a Little Extra: A Guide to Healthy Pregnancy for the Plus-Size Woman (Berkley Publishing Group, 2003), says that eating disorders can effect a woman's fertility, but the desire to become pregnant is so powerful that many women can overcome their problem – at least long enough to conceive and carry a pregnancy to term. But, it's important to work with your doctor to address the problem and become healthy enough to get pregnant.

The two most common eating disorders are anorexia and bulimia. A person with anorexia strictly controls caloric intake, often to the point of near-starvation. Bulimics control calories through purging, or vomiting, after meals. Both anorexics and bulimics often exercise to excess and use laxatives and diuretics inappropriately. An overlap between the two disorders, as was apparently the case with Schiavo, is not unusual.

To put it simply, in order to conceive, a woman must have a certain percentage of body fat. This not only controls our monthly cycles, it's what controls the onset of menstruation. As Clark points out in her book, once this cycle is established, it is body fat dependent.

When a person diets, most of the weight loss is fat. As a result, a relatively small percentage of weight loss can represent a large percentage of total body fat. This loss of body fat causes the body to conserve energy in anyway it can. "Someone who is severely anorexic doesn't have enough body fat to support their own needs through the calories they're eating," says Clark. "The body recognizes that a pregnancy can't be supported, and ceases to menstruate because that's not a necessary function."

The effect of caloric restriction on conception isn't limited to women. Dr. Jack Katz, chairman of the department of psychiatry at North Shore University Hospital at Manhasset, says that an extreme drop in body fat has a similar effect on male fertility. "In males who are anorective, the analog to the cessation of menses is their sperm count drops once their weight gets below 15 to 20 percent of body," he says. "This causes their fertility to drops substantially. Once they gain weight, they can become fertile."

In bulimia, there often isn't this loss of body fat, as Dr. Katz points out, so bulimia may not affect conception. "We do have to differentiate between a normal-weight bulimic and women with anorexia," he says. "The rate of infertility in women who meet the criteria of anorexia nervosa is very high – I'd say close to 100 percent. Those who suffer from bulimia may ovulate. Certainly some can become pregnant, but whether you can maintain it is another story. It's not a healthy situation for the woman or for the pregnancy."

Want to see more?

• The Skinny on Weight While Trying to Conceive
• Too Toxic to Conceive: Is Your Lifestyle to Blame?
• A Weighty Issue: Trying to Conceive When You're Overweight
• Talk about it!