KatCarney

Modest weight loss goes far in PCOS patients - Better Endocrine, Reproductive Function

Erik L. Goldman
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).

Forty-five mildly obese women with PCOS were enrolled.

The patients, all of whom were anovulatory or cycling erratically, were randomly assigned to one of the diets. The subjects had a mean age of 33 and a mean baseline Body Mass Index (BMI) of 38. Baseline insulin levels were suggestive of insulin resistance, as is typical of patients with PCOS.

The-16-week dietary intervention had two phases: a 12-week energy-restricted phase, in which the patients were permitted only 1,433 kcal/day regardless of which diet they were on; and a 4-week weight maintenance phase in which calorie content was increased slightly, but relative proportions of protein, carbohydrates, and fats remained the same.

Patients also participated in a once-weekly exercise class, and were encouraged to increase their exercise to at least 3 times per week.

A total of 14 patients in each group completed the trial, with 17 dropping out owing to pregnancy, illness, or "personal issues."

The patients lost a mean of 7.7 kg. Those on the high-protein diet lost slightly more weight (8.5 kg versus 6.9 kg), but the investigators considered the diets essentially equivalent from a weight loss viewpoint. There was an overall reduction of 14.4% in total fat mass, and a 12.5% mean drop in abdominal fat mass.

The relatively small changes in body mass had significant reproductive, endocrine, and metabolic effects. A total of 44% of all patients completing the diets had improvements in menstrual cycling, including a restoration of ovulation in some cases. Three women became pregnant during or shortly after the course of the study, with approximate conception times determined to be within the 16-week time frame.

The most striking difference between the patients who had restored cycling and those who did not was the correlation with improvement of insulin sensitivity. Among the responders, the energy restriction phase produced a mean 34.9% decrease in fasting insulin, and a 21.3% decline in HOMA (homeostasis model assessment), a surrogate measure of insulin resistance. These changes were maintained during the higher-calorie weight maintenance phase (J. Clin. Endocrinol. Metab. 88[2]:812-19, 2003).

In those patients who had no positive changes in reproductive function, there were no changes in insulin resistance or HOMA.

These new findings build on earlier studies showing that weight loss and normalization of insulin sensitivity can have many benefits in women with PCOS. These include return to normal reproductive function as well as improving lipid profiles and reducing the risk of cardiovascular disease and diabetes, both of which are more common in PCOS patients than non-PCOS controls.

COPYRIGHT 2003 International Medical News Group
COPYRIGHT 2003 Gale Group
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