Weight Loss Improves Metabolic, Endocrine, and Clinical Parameters in Women With PCOS
Kristin M. Richardson
Jan. 24, 2003 — Overweight women with polycystic ovary syndrome (PCOS) who lose weight through either a high-protein or a high-carbohydrate diet experience improved metabolic, endocrine, and clinical parameters, according to the results of a clinical trial to be published in the February issue of the Journal of Clinical Endocrinology & Metabolism.
Sarah L. Berga, MD, a reproductive endocrinologist at the University of Pittsburgh School of Medicine in Pennsylvania, presented the findings at an American Medical Association press briefing on hormone disorders in New York City. The study was conducted by researchers at the University of Adelaide, Australia.
“Currently, there is no cure for PCOS, which can have devastating physical and emotional effects on reproductive-age women and put them at risk for more serious health conditions, such as diabetes and heart disease,” said Dr. Berga.
PCOS is one of the most common endocrinopathies in women, with an estimated prevalence among reproductive-age women of 4% to 12%. Clinical signs are heterogenous and may include hirsutism, acne, obesity, menstrual dysfunction, infertility, and enlarged polycystic ovaries. Recent research has demonstrated that PCOS has significant metabolic consequences and is associated with increased risk of type 2 diabetes, dyslipidemia, cardiovascular disease, and endometrial hyperplasia and cancer. The etiology is unknown, but there is a growing understanding that the underlying disorder is insulin resistance with consequent hyperinsulinemia that stimulates thecal cell androgen production and results in hyperandrogenism.
Weight loss has been a primary intervention in PCOS. Even so, Dr. Berga pointed out, “Believe it or not, when patients ask the simple questions: ‘how much weight do I need to lose and what type of diet is best?’ we don’t have the answers.”
In this study, 45 overweight white women were randomized to a high-protein ([HP] 40% carbohydrate, 30% protein, 30% fat) or a low-protein ([LP] 55% carbohydrate, 15% protein, 30% fat) diet for 16 weeks. In the first phase of the study, which continued for 12 weeks, caloric intake was restricted. The next four weeks of the study focused on weight maintenance. Both the HP and the LP diets were nutritionally complete, and caloric intake and saturated fat intake did not differ between the two diets. All women in the study attended a weekly education/exercise class and were advised to exercise at least 3 times a week. Twenty-eight subjects completed the study (mean baseline body mass index, 37 ± 1.24 m2).
Weight loss and improvements in lipid profile, menstrual cyclicity, and insulin resistance occurred independently of diet type.
Both the HP and the LP diets achieved weight loss. Overall, there was a combined decrease of 14.4% in total fat mass and a 12.5% decrease in abdominal fat, a common symptom of PCOS.
Over the 16 weeks of the study, total cholesterol decreased 8.8%, triglycerides decreased 12.5%, and low-density lipoprotein cholesterol decreased 9.8%, independently of diet composition. The HP diet, however, prevented a decrease in high-density lipoprotein cholesterol during the caloric restriction phase of the study.
Forty-four percent of the women in the study experienced improvements in their menstrual cycle. Insulin resistance (measured by the homeostasis model) and fasting insulin also improved in this group of women, which is consistent with the postulated relationship between insulin resistance and hyperandrogenism.
“These findings hint that women with PCOS should lose enough weight to improve their insulin action,” Dr. Berga said. “This information can also help doctors and patients develop a diet and exercise routine that will appropriately and effectively work to treat the symptoms of PCOS,” she added.
Study limitations include a high dropout rate and consequently reduced study power. “Larger and longer placebo-controlled studies are needed in the future to confirm these findings,” said Dr. Berga.
J Clin Endocrinol Metab. 2003;88:812-819
Reviewed by Gary D. Vogin, MD
Kristin M. Richardson is site editor of Medscape Diabetes and Endocrinology.