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:
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:
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:
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.
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
More Than Just a Risk Factor for Disease
The number of people with metabolic syndrome is increasing, yet those who have it often aren't aware of its significance. Originally identified as Syndrome X by Dr. Gerald Reaven in the 1980s, metabolic syndrome increases risk for cardiovascular disease, heart attack, stroke, and diabetes. It is diagnosed in people who have central obesity (waist circumference >35 inches in women or >40 inches in men) and meet at least two of the following criteria as set forth by the American Heart Association:
The majority of people with metabolic syndrome have prediabetes, defined as fasting blood glucose between 100-125 mg/dL and/or hemoglobin A1c between 5.7-6.4%. Interestingly, people with hypertension may have better overall glycemic control as a result of producing large amounts of insulin, but they often develop heart disease at higher rates because of persistent and significant hyperinsulinemia. Unfortunately, it's easier to dismiss concerns about you're health when you're told you "only" have prediabetes.
Insulin resistance is defined as the inability of cells to respond normally to insulin, resulting in higher blood glucose and insulin levels. It's the hallmark of metabolic syndrome. Recently it has been suggested that hyperinsulinemia may be what causes insulin resistance rather than the more commonly held view that insulin resistance leads to increased insulin output and subsequent hyperinsulinemia. Regardless of which occurs first, high levels of serum insulin result in elevated blood pressure, inflammation, and high triglycerides and VLDL cholesterol -- all of which increase the risk for vascular events, i.e., heart attack and stroke. Unfortunately, most people who are diagnosed with prediabetes or metabolic syndrome don't realize that they've already sustained damage. For instance, it's estimated that 50% of people already have heart disease at the time diabetes is diagnosed.
Lifestyle Goals: Is Standard Advice Helpful or Harmful?
The goals of treatment for metabolic syndrome are obvious: weight loss and improvement in blood pressure and lab values. Aside from drug therapy for lipids and blood pressure, what can be done from a nutritional standpoint? Here is the standard advice I found on many highly regarded websites, including the National Heart, Blood, and Lung Institute (NHBLI) site:
A typical recommendation is to achieve and maintain a BMI of <25, which may not be possible or even desirable for everyone, particularly muscular, large-framed men. The BMI is also meaningless for assessing abdominal girth and body fat vs. muscle. For instance, a man with a BMI of 28 with little body fat and a 32-inch waist is metabolically much healthier than a small-framed man with a BMI of 24, a 38-inch waist, and a considerable amount of visceral fat around his organs. Of course, in people with metabolic syndrome abdominal obesity is a given, but the goal should be decreasing waist circumference rather than BMI.
Follow a Heart-Healthy Diet
It really shouldn't surprise me at this point that the "heart-healthy diet" -- essentially the DASH diet -- so often advised for people with metabolic syndrome isn't the one I'd recommend. From the NHBLI website:
"Fill half your plate with fruits and vegetables. A healthy diet also includes whole grains, fat-free or low-fat dairy products, and protein foods, such as lean meats, poultry without skin, seafood, processed soy products, nuts, seeds, beans, and peas."
Yes, "processed" soy products.
So according to these recommendations, the following meal plan would be ideal:
Bowl of Raisin Bran cereal with sliced banana and skim milk
Turkey sandwich with low fat mayo on whole grain bread, orange
Yoplait Light yogurt with fruit
Tofu, rice, and vegetables with low-sodium teriyaki sauce
This advice is being given to individuals with metabolic syndrome, who by definition have insulin resistance and hyperinsulinemia with elevated triglycerides, low HDL, and/or impaired fasting glucose. Unless carbohydrate portions are kept very small and fat is added -- neither of which is recommended on a low-fat diet -- these guidelines are likely to exacerbate rather than improve biomarkers and weight. And, let's face it, this plan doesn't sound that appetizing or satiating and would be difficult to sustain for most people.
An Enticing Alternative: Carbohydrate Restriction
On the other hand, research has demonstrated that low-carbohydrate diets do the following:
Clearly, metabolic syndrome responds extremely well to carbohydrate restriction. Is there any other diet that has shown such impressive results? Some would argue that the Mediterranean Diet has demonstrated health benefits in this population, and there are certainly studies that support this claim. However, if large quantities of fruits, starchy vegetables, and grains are consumed, a Mediterranean diet plan can be as high in carbs as the low-fat plan listed above. Dr. Steve Parker has devised two Mediterranean-based diets that are appropriate for people with Metabolic Syndrome: the Low-Carb Mediterranean Diet and the Ketogenic Mediterranean Diet.
Here's an example of a low-carbohydrate meal plan based on Mediterranean Diet principles:
Greek yogurt with raspberries and chopped walnuts
Shrimp, tomatoes, and cucumbers with olive oil and basil
Mixed nuts or olives
Steak with grilled zucchini, mushrooms, and eggplant
Strawberries with whipped cream
I think that sounds like a pretty enjoyable and sustainable way of eating.
And yet in most papers, on most websites, and among most endocrinologists, carbohydrate restriction isn't even discussed as an option for metabolic syndrome. "Lose weight" seems to be the primary directive, and the recommendation for achieving this is typically a low-fat, low-sodium, high-carb approach. Interestingly, much of the research on hyperinsulinemia and insulin resistance over the past two decades has been published in Diabetes and Diabetes Care, which are journals of the American Diabetes Association, an organization which recently changed its position statement to include low-carbohydrate diets as an option for people with diabetes and prediabetes. I hope other organizations will follow their lead and begin promoting carbohydrate restriction as an option -- or better yet, the best option -- for those with metabolic syndrome.
1. Shanik MH, et al. Insulin resistance and hyperinsulinemia: Is hyperinsulinemia the cart or the horse? Diabetes Care 2008 Feb: 31 Suppl 2: S262-8
2. Reaven GM. Banting lecture 1988: Role of insulin resistance in human disease. Diabetes 1988 Dec;37(12); 1595-607
3. McGavock JM, et al. Cardiac steatosis in diabetes mellitus. Circulation 2007 Sep 4;116(10):1170-5
4. Winhofer Y, et al. Short-term hyperinsulinemia and hyperglycemia increase myocardial lipid content in normal subjects. Diabetes 2012 May;61(5):1210-1216
5. 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
6. Castorini CM, et al. The effect of Mediterranean diet on metabolic syndrome and its components. J Am Coll Cardiol 2011 Mar 15:57(11)1299-313
Franziska Spritzler, RD, CDE