Defending a Carbohydrate-Restricted Option for PCOS Management

As a registered dietitian and certified diabetes educator, I'm required to complete 75 hours of continuing education (CE) every five years. Fortunately, there are many ways to fulfill this requirement, including watching webinars, attending conferences, and completing exams on nutrition-related books. Although my recertification date is more than a year away, I've been trying to complete as many CE units as I can ahead of time, including a short course on nutritional management of Polycystic Ovary Syndrome (PCOS).

Although the author of the course gave a good overview of the disease and recommended avoiding  refined carbohydrates, I found that several of the dietary suggestions were not particularly helpful for many women who struggle with PCOS, such as:

• Eat plenty of whole grains, starchy vegetables, and beans
• 130 grams of carbohydrate per day is the bare minimum that should be consumed, and meals should preferably contain 45-60 grams of carbohydrate each
• Snacks should include approximately 15 grams of carbohydrate combined with a protein food (i.e., peanut butter on crackers)

PCOS is one of the most common endocrine disorders among reproductive-aged women, as well as the leading cause of infertility. Instead of an egg being released from one of the follicles in the ovaries on a monthly basis as occurs in normal ovulation, a hormonal imbalance  (too much luteinizing hormone and not enough follicle stimulating hormone) results in the egg failing to mature; instead, the follicle forms a small cyst.  This process is repeated, and eventually the ovaries contain dozens of these cysts. Although the clinical presentation varies from person to person and some women have few symptoms, its hallmarks are insulin resistance and hyperinsulinemia. Other common features include:

• obesity 
• acanthosis nigricans (skin tags and darkened pigment in skin folds, such as the armpits, groin, thighs, and neck), a sign of insulin resistance and hyperinsulinemia
• menstrual irregularities such as ammenorrhea (skipped periods) and menorrhagia (heavy periods) as a result of not ovulating
• masculinization, including hirsutism (excessive facial and body hair), acne, male-pattern baldness, and deep voice related to increased ovarian production of testosterone and other androgens
• depression

Women with PCOS are more than twice as likely to meet the criteria for metabolic syndrome as those without the disorder; in fact, in one study, women between the ages of 20-39 were found to have a 4-fold to 8-fold increased prevalence of metabolic syndrome compared to women of the same ages in the general population (1). Those with both PCOS and metabolic syndrome are therefore at much higher risk for developing type 2 diabetes and cardiovascular disease. Since research has demonstrated that carbohydrate restriction improves markers of insulin resistance (IR) and other features of metabolic syndrome (2), it would seem logical to consider it an appropriate -- if not the most appropriate -- diet for PCOS. Even nonobese women with PCOS experience IR, though, and are at increased risk for progression to diabetes in the future. 

A small 2005 study evaluating the effects of a ketogenic diet on women with PCOS found significant improvements in fasting insulin, body weight, and hormone levels among subjects who completed the study -- including two pregnancies in women who had previously been unable to conceive (2).

This is why I find it disappointing to read recommendations like those given in the PCOS course, which sound very similar to the one dietitians often make for people with diabetes. While this type of diet may work for insulin-sensitive people, it simply doesn't result in beneficial outcomes for most women with insulin resistance and hyperinsulinemia. For people with defective hormonal regulation, it can be difficult to control insulin levels and appetite when eating more than minimal amounts of carbohydrate. 

The authors of a recent review looking at six different diets and their effects on physiological and psychological outcomes in women with PCOS  came to the following conclusion: "Weight loss should be targeted in all overweight women with PCOS through reducing caloric intake in the setting of adequate nutritional intake and healthy food choices irrespective of diet composition (4)."

While the researchers noted moderate to severe bias among all the studies, I found some other issues:

1. In one study, the "low carbohydrate" diet contained 2000 calories with 43%  as carbohydrates, which equates to 215 grams -- not low in carbs, by most standards. However, it still resulted in greater weight loss and improvements in postprandial insulin response than a high-monounsaturated-fat diet containing 55% of calories (275 grams) as carbohydrate (5). 
2. Stamets, et al., reported that for diets containing 1000 calories, carbohydrate intake of 40% (100 grams) vs. 55% (138 grams) didn't seem to matter much; at such hypocaloric intakes, insulin levels would be expected to improve significantly, and they did (6). But who can maintain such a low-calorie diet for any length of time without getting hungry and experiencing a  lowering of metabolic rate and other adverse effects? This was only a one-month study, fortunately, but to the participants it probably felt longer.
3. Another study investigated the responses of women with PCOS who followed a carb-counting vs. fat-counting diet for six months after completing an 8-week  diet containing meal replacements for two meals a day. Interestingly, the caloric intakes were nearly the same -- 1396 for the carb-counters and 1475 for the fat-counters -- and the amount of carbohydrates consumed was also very close, at 140 grams and 158 grams, respectively. (Protein intake was 21% in each group, and fat was 35% in the carb-counting group and 31% in the fat-counting group.) The researchers' findings? "No significant difference between any outcomes." Not surprising when the composition of the two diets was so similar.

The other three studies didn't look at "low-carb" diets per se but found less depression and  lower triglycerides in subjects consuming higher amounts of protein and improvements in insulin sensitivity among women following a low GI diet. 

My point is that aside from one small study, researchers haven't attempted to investigate whether a very-low-carbohydrate diet containing adequate calories is effective in improving IR and hyperinsulinemia, promoting weight loss, and improving hormonal balance in order to reduce masculinization and facilitate ovulation. However, I've read anecdotal reports  where carb restriction did improve symptoms, and at least one woman I've worked with definitely experienced benefits. There's also the spontaneous decrease in caloric intake that occurs for many, although not all, people who consume a carbohydrate-restricted diet (8).

Now, I'm not claiming that low-carb diets work for everyone or that they're the only thing needed to achieve results. Certainly insulin-sensitizing medications such as metformin, stress management, exercise, support groups, and supplements play a large role in managing PCOS as well. But for the overweight woman suffering from this disorder, I don't feel that it's enough to simply encourage weight loss without providing guidance on how to do so in a sustainable way that  has been shown to improve IR and insulinemia -- i.e., limiting carbs to 50 net grams per day or less.  

I understand that some women with PCOS may not want to follow a carb-restricted diet, and I certainly respect and support everyone's  right to make dietary choices. But I believe dietitians and other healthcare professionals who work with women who struggle with PCOS should present a low-carb diet as an option rather than insist that everyone consume "a minimum of 130 grams of carbohydrate per day." Unless you have lived with PCOS, diabetes, or metabolic syndrome and tried carbohydrate restriction, it's impossible to understand what an impact making this type of change could have on your health and quality of life.

* Please speak with your doctor or health care provider prior to making any changes to your diet.


References:
 
1. Apridonidze T, et al. Prevalence and Characteristics of the Metabolic Syndrome in Women with Polycystic Ovary Syndrome. J Clin Endocrinol Metab. 2005 Apr;90(4):1929-35
2. Volek JS, Feinman RD.Carbohydrate restriction improves features of the Metabolic Syndrome. Metabolic Syndrome may be defined by the response to carbohydrate restriction. Nutr Metab(Lond) 2005 ;2:31
3. Mavropoulos JC, et al. The effects of a low-carbohydrate, ketogenic diet on the polycystic ovary syndrome: A pilot study. Nutrition & Metabolism. 2005;2:35
4. Moran IJ, et al. Dietary composition in the treatment of polycystic ovary syndrome: a systematic review to inform evidence-based guidelines. J Acad Nutr Diet. 2013 Apr;113(4):520-45
5.  Douglas CC, et al. Role of diet in the treatment of polycystic ovary syndrome. Fertil Steril.2006; 85(3):679-688
6.  Stamets K, et al. A randomized trial of the effects of two types of short-term hypocaloric diets on weight loss in women with polycystic ovary syndrome. Fertil Steril. 2004;81(3):630-637
7.  Moran LJ, et al. Short-term meal replacements followed by dietary macronutrient restriction enhance weight loss in polycystic ovary syndrome. Am J Clin Nutr. 2006;84(1):77-87
8. Westman EC, et al. Low carbohydrate nutrition and metabolism. Am J Clin Nutr.August 2007; 86(2):276-284

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