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
Today my friend and colleague, Lily Nichols, a fellow registered dietitian and certified diabetes educator, shares her insight on carbohydrate-restricted diets during pregnancy. This is a controversial topic that I believe deserves more attention and investigation, which Lily does brilliantly in the following article.
Is It Safe to Go Low Carb During Pregnancy?
With the wide adoption of low-carbohydrate diets, many people question if they are safe during pregnancy. While quite a few women use a lower carbohydrate diet to conceive (since they are especially useful for women struggling with infertility), most medical professionals discourage women from continuing this diet during pregnancy. I find it ironic that if you tell your doctor that you plan to eat low carb during pregnancy, they’ll say it’s unsafe, but if you say you plan to eat a diet based on fresh vegetables, meat, fish, eggs, dairy, nuts, seeds, and a little fruit, they’ll encourage you to stay the course. The controversy over the safety of low carbohydrate diets in pregnancy stems primarily from misconceptions around ketosis. It’s incorrect, but widely accepted, that ketosis during pregnancy is harmful to a developing baby.
When I first dove into the research, I was shocked to find that studies on healthy, non-diabetic pregnant women (eating a “regular” diet) show a marked elevation in ketones after a 12-18 hour fast, which is akin to eating dinner at 8pm and having breakfast at 8am (or skipping breakfast entirely). What’s more interesting is that pregnancy actually seems to favor a state of ketosis. Compared to non-pregnant women, blood ketone concentrations are about 3-fold higher in healthy pregnant women after an overnight fast. And in late pregnancy, metabolism shifts to a state of catabolism, making ketosis even more frequent. Knowing this, I would expect that every pregnant woman experiences ketosis at some point during her pregnancy (particularly if she experiences nausea or food aversions!).
I find it hard to believe that our bodies would perpetuate a state of ketosis if it was truly harmful to a baby, but I continued my research into the topic. The majority of studies on ketosis are actually looking at diabetic ketoacidosis (DKA) or starvation ketosis, not nutritional ketosis (induced by eating a low amount of carbohydrates).
First, let me state that diabetic ketoacidosis is an extremely dangerous phenomenon, pregnant or not, that occurs in people with insulin dependent diabetes. This is classically due to skipping insulin shots, incorrectly dosing insulin, or taking inadequate insulin to cover unexpected elevations in blood sugar. Unlike nutritional ketosis or starvation ketosis, DKA is accompanied by unnaturally high levels of ketones from complete insulin deprivation and blood sugar levels at least three times higher than normal, which profoundly and dangerously alters the acid-base balance in the body. The blood sugar levels seen with DKA are themselves teratogenic (can cause birth defects), so this state should obviously be avoided by pregnant women. Some studies have suggested the metabolic effects of diabetic ketoacidosis may harm fetal brain development.
However, to assume that all ketosis is harmful to a developing baby is illogical. For example, nutritional ketosis (the type of low level ketosis sometimes experienced on a low carbohydrate diet) is accompanied by normal blood sugar levels, blood ketones at very low levels (in general, thirty-fold less than what’s seen in diabetic ketoacidosis), and normal acid-base balance in the blood. So if a woman eats a lower carbohydrate diet during pregnancy, she might experience ketosis from time to time, but it’s not anywhere close to ketone levels induced by DKA in a pregnant woman with uncontrolled diabetes. Even if a woman tests positive for urinary ketones, it’s highly unlikely her blood ketone levels will be elevated. Studies on pregnant women who test positive for urine ketones rarely have detectable levels in the blood.
Despite all the medical warnings about ketones “harming the fetus”, it turns out the fetal brain actually gets approximately 30% of its energy from ketones. In fact, ketones are used by the growing fetus to synthesize a variety of essential cerebral lipids, which perhaps helps explain why ketosis is more common in the third trimester. And get this: Ketones are so important for fetal development, that researchers believe the fetus manufactures its own ketones. Umbilical venous blood samples (fetal blood supply) indicate significantly higher ketone concentrations compared to maternal levels in healthy pregnant women in their second and third trimesters.
So although the fetus requires glucose for growth, it also requires ketones. Either fuel provided in excess is harmful to the developing fetus, but as long as a mom is consuming enough calories and maintaining normal blood sugar levels, the baby will get just the right mix.
Given all of this information, I’ve changed my stance on the recommended carbohydrate levels for pregnant women and believe that it is safe to go low carb during pregnancy - at least lower than the arbitrary “minimum” of 175g per day suggested by most dietitians.
Now before you cut out all carbs, know that there are a variety of carbohydrate foods that pregnant women should continue to eat, including vegetables, fruit, nuts, seeds, and if they are tolerated, dairy and legumes. Eating fewer carbohydrates generally means women will eat less refined grains, junk foods, and added sugars, leaving more room for nutrient-dense foods that provide a growing baby with essential nutrients.
Many women do just fine eating a more moderate level of carbohydrates in pregnancy, so I do not believe everyone needs to goes low carb. But if you have medical conditions that are tied to blood sugar issues, such as gestational diabetes, preeclampsia, or you simply want to prevent excess weight gain, you should know it’s safe to eat a lower carbohydrate diet while pregnant.
*This article includes excerpts from Lily’s book, Real Food for Gestational Diabetes: An Effective Alternative to the Conventional Nutrition Approach, which includes an entire chapter exploring the research on ketosis during pregnancy.
Lily Nichols, RDN, CDE, CLT is one of the country’s most sought after ‘real food for pregnancy’ experts whose approach to nutrition embraces real food, integrative medicine, and mindful eating. You can learn more about Lily by visiting her popular blog, www.PilatesNutritionist.com and get her book, Real Food for Gestational Diabetes (and snag an exclusive FREE guide on managing gestational diabetes) at www.realfoodforGD.com.
 Mavropoulos, John C et al. "The effects of a low-carbohydrate, ketogenic diet on the polycystic ovary syndrome: a pilot study." Nutr Metab (Lond) 2 (2005): 35.
 Metzger, BoydE et al. "" Accelerated starvation" and the skipped breakfast in late normal pregnancy." The Lancet 319.8272 (1982): 588-592.
 Felig, Philip, and Vincent Lynch. "Starvation in human pregnancy: hypoglycemia, hypoinsulinemia, and hyperketonemia." Science 170.3961 (1970): 990-992.
 Herrera, E. "Metabolic adaptations in pregnancy and their implications for the availability of substrates to the fetus." European journal of clinical nutrition 54.1 (2000): S47.
 Rizzo, Thomas A et al. "Prenatal and perinatal influences on long-term psychomotor development in offspring of diabetic mothers." American journal of obstetrics and gynecology 173.6 (1995): 1753-1758.
 Coetzee, EJ, WPU Jackson, and PA Berman. "Ketonuria in pregnancy—with special reference to calorie-restricted food intake in obese diabetics." Diabetes 29.3 (1980): 177-181.
 Institute of Medicine (US). Panel on Micronutrients. Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein and Amino Acids. Panel on Macronutrients Panel on the Definition of Dietary Fiber, Subcommittee on Upper Reference Levels of Nutrients, Subcommittee on Interpretation and Uses of Dietary Reference Intakes, and the Standing Committee on the Scientific Evaluation of Dietary Reference Intakes, Food and Nutrition Board. National Academies Press, 2005.
 Bon, C et al. "[Feto-maternal metabolism in human normal pregnancies: study of 73 cases]." Annales de biologie clinique Dec. 2006: 609-619.
Franziska Spritzler, RD, CDE