Modest weight loss goes far in PCOS patients. (Better Endocrine, Reproductive Function).

NEW YORK -- Modest calorie restriction can have a profound effect on reproductive and endocrine function in some overweight women with polycystic ovary syndrome, Dr. Sarah L. Berga said at a media briefing on pituitary/hormonal disorders sponsored by the American Medical Association.

The key is in reversing insulin resistance, and this can be accomplished through moderate weight loss, said Dr. Berga, director of reproductive endocrinology and infertility at the University of Pittsburgh.

Data from a just published Australian study indicate that relatively small weight losses of 6-10 kg over a 4-month period can have measurable beneficial effects on insulin sensitivity. This in turn can restore a more normal reproductive hormone profile. In some cases, the ultimate result is a return to normal ovulation, menstrual cycling, and fertility, she said at the briefing, also sponsored by the Pituitary Network Association.

Dr. Berga acknowledged that there is something of a chicken-and-egg relationship between insulin resistance, overweight, hyperandrogenism, and abnormal reproductive function in polycystic ovary syndrome (PCOS) women. In other words, it is difficult to determine which factor is the fundamental abnormality underlying the syndrome.

She believes PCOS may reflect the "thrifty genotype," indicating a genetic predisposition toward energy storage. "In human kind's evolutionary history, we never had enough food. People with the thrifty genotype were more able to store energy. The bad news is that in times of plenty, as we have now, these people cannot rev up their metabolism to burn off the extra calories," she said.

Fortunately, clinically significant changes can be attained with relatively modest dietary changes as shown in the Australian study, she said.

The study, led by Dr. Lisa J. Moran of the University of Adelaide (Australia), compared two diets with equivalent total daily calorie and total fat content: a high-protein/low-carbohydrate diet (30% protein, 40% carbohydrate, 30% fat) and a low-protein/high-carbohydrate diet (15% protein, 55% carbohydrate, 30% fat).