Why Protein Is Important in a PCOS Diet

Multiple sources of protein sitting on a table

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Protein is one of three nutrients that provide calories alongside carbohydrates and fat. Protein functions as the building blocks for bones, muscles, skin, and blood as well as the enzymes, hormones, and vitamins your body needs to function normally. If you have polycystic ovary disease (PCOS), eating a diet higher in protein and lower in carbohydrates may help overcome weight gain and diabetes common in women living with the disease.

Benefits of Protein in PCOS

Proteins are responsible for numerous functions in the human body, including the maintenance of bones, muscles, skin, and hair. Protein also helps facilitate digestion and metabolism and plays an integral role in the synthesis of hormones, including estrogen, testosterone, and insulin.

In women with PCOS, many of these functions are impaired due to the dysregulation of hormones, most specifically increases in testosterone and insulin levels.

While diet alone will not “cure” PCOS or temper the mechanisms that give rise to the disease, a diet rich in protein and low in carbohydrate may help prevent or reverse weight gain common in women with PCOS. It may also reduce the risk of type 2 diabetes, a condition affecting more than half of all women with PCOS by the age of 40, or prevent prediabetes from progressing to diabetes.

Studies have shown that an increase in protein intake can achieve these aims in several different ways:

  • Protein Helps Boost Metabolism: As a facilitator of metabolism, protein can help boost the conversion of calories into energy when the intake is increased. Eating more protein can, in fact, boost the daily calorie expenditure (the amount burned) by as much as 100 calories.
  • Protein Makes You Fuller Faster: High protein diets can increase satiation (the feeling of fullness after eating). It does so by stimulating the production of the hormones cholecystokinin, glucagon-like peptide 1, and peptide YY, each of which is involved in satiety. Doing so can increase appetite control and reduce cravings even if overall calories are reduced.
  • Protein May Burn Calories Better: All the foods we eat have a thermic effect, meaning that they increase the rate of metabolism, albeit to different levels. Protein has by far the greatest thermic effect (between 15% and 30%) compared to carbohydrates (5% to 10%) and fat (0% to 3%).
  • Protein May Help Improve Blood Sugar Control: All the foods we eat can trigger a glycemic response in which blood sugar (glucose) levels increase. Because proteins tend to be digested slowly, their impact on blood sugar is relatively low. A 2019 study published in the journal Diabetologia reported that adults with type 2 diabetes fed a high-protein diet for six weeks had reductions in both postprandial (post-eating) and fasting glucose levels.
  • Protein May Temper the Insulin Response: Protein stimulates the release of glucagon, a hormone that raises blood glucose levels and counteracts the action of insulin. Eating the right amount of protein can help balance the levels of glucagon and insulin in the blood (although it is doubtful that eating more protein can altogether "fix" the hormonal dysregulation of PCOS).

Recent studies in women with PCOS appear to support these findings.

A 2012 study from Denmark reported that women with PCOS who ate a high-protein diet for six months achieved a mean weight loss of 9.7 pounds (4.4 kilograms) and a mean body fat loss of 9.5 kg (4.3 kilograms) compared to those who ate a standard diet.

Similar results were seen in a 2012 study from Iran in which the use of a high-protein diet (over 30%) in 60 overweight women with PCOS led to reductions in body weight and testosterone levels as well as improved insulin sensitivity.

Dietary Recommendations

There are no specific dietary recommendations issued for women living with PCOS. With that said, the current body of evidence suggests that a high-protein diet (in which 30% to over 40% of calories are from protein) is superior to a standard diet (in which less than 15% of calories are from protein).

This is along the top end of recommendations offered by the Department of Health and Human Services (DHHS), in which women 19 and over are to get 10% to 35% of their daily calories from protein.

DHHS Recommendation for Daily Protein Intake in Grams (g)
Age Female Male
1-3 13 g 13 g
4-8 19 g 19 g
9-13 34 g 34 g
14-18 46 g 52 g
19-30 46 g 56 g
31-50 46 g 56 g
51 and oer 46 g 56 g

There are reasons for DHHS guidance. Even though protein is broken down slowly, around 50% of 60% of it will be converted to glucose. If eaten alone, its effect on the blood sugar is minimal since the glucose will be distributed to the bloodstream at a slow, steady pace.

The same may not be true when protein, carbohydrate, and fat are combined. In some cases, protein can actually increase blood sugar levels if the balance of protein, carbohydrates, and fat is not carefully controlled.

A 2015 review of studies in Diabetes Care demonstrated this, reporting that combining 30 grams of protein with 35 grams of carbohydrates can increase postprandial blood glucose by 2.6 mmol/L. In some people, this is enough to push them from a normal to a high blood sugar level.

However, if used correctly, a high-protein diet may help you achieve the weight loss and blood sugar control you need.

According to a 2014 study in the Archives of Gynecology and Obstetrics, even a 5% drop in weight can improve insulin sensitivity, hyperandrogenism (high testosterone), menstrual function, and fertility in women with PCOS.

Tips and Considerations

If you decide to embark on a high-protein diet, it is best to work with a dietitian experienced in metabolic disorders. In this way, you can devise a dietary strategy that not only meets your nutritional needs but also helps you achieve weight loss safely and sustainably.

Generally speaking, to lose one pound of weight per week, you would need to reduce your daily calorie intake by 500 calories. This makes preparation all the more important since you will not only need to reduce calories but do so with an entirely new ratio of protein, carbohydrates, and fats.

Although the ratio of nutrients consumed in a high-fat diet is roughly sketched out (around 30% to 40% of calories from fat and 30% from fat), it is by no means definitive and may need to be adjusted based on your health, weight, age, and fitness/activity level. If you are an athlete, for example, you would invariably need to consume more protein than someone who is largely sedentary.

To ensure the right ratio, you will first need to learn how to read food labels and count calories. Although the glycemic index (GI) can be valuable in choosing foods least likely to affect your blood sugar, it is more important to count calories for weight loss purposes. (Some low-GI foods are very high in calories.)

There are numerous online calculators and apps you can use to tally the percentage of protein, carbs, and fat you eat each day. It may also be useful to start a meal diary so that your food intake is regulated not only over the course of the day but with each and every meal. In this way, the proportion of your food you eat at one sitting will be consistent and less likely trigger hyperglycemia (high blood sugar);

If you have diabetes, it is also important to talk with your doctor before starting any diet and to have your condition routinely monitored. The same applies if you have advanced kidney disease in which a high-fat diet may be contraindicated.

Protein Sources

In order to meet your increased protein needs, you need to select protein sources carefully so that you neither have to eat large quantities nor expose yourself to excess calories or saturated fat (such as red meat, an otherwise ideal source of protein).

Some of the foods especially high in protein include:

  • Almonds: 6 g protein and 164 calories per ounce
  • Eggs: 6 g protein and 78 calories per egg
  • Greek Yogurt: 7 g protein and 100 calories per 6-ounce serving
  • Milk: 8 g protein and 149 calories per cup
  • Quinoa: 8 g protein and 222 calories per one cup (cooked)
  • Pumpkin Seeds: 9 g protein and 158 calories per 1-ounce serving
  • Oatmeal: 11 g protein and 307 calories per one cup (uncooked)
  • Lentils: 18 g protein and 230 calories per one cup (cooked)
  • Shrimp: 20 g protein and 84 calories per 3-ounce serving
  • Lean Sirloin: 25 g protein and 186 calories per 3-ounce serving
  • Turkey Breast: 26 g protein and 125 calories per 3-ounce serving
  • Canned Tuna: 27 g protein and 128 calories per can
  • Cottage Cheese: 28 g protein and 163 calories per cup
  • Soybeans: 29 g protein and 173 calories per cup
  • Chicken Breast (Without Skin): 53 g protein and 284 calories per half breast

Protein powders and shakes can also be useful in boosting your daily intake but should not be used as a substitute for real food.

Animal vs. Plant-Based Proteins

Not all proteins are created equal. There are complete proteins that contain all nine essential amino acids that the body needs to function normally (histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine) and incomplete proteins that do not.

Dietary protein is derived from two different sources: plant-based sources (such as soy, nuts, and beans) or animal-based sources (such as meat, poultry, fish, dairy, and eggs). With the exception of soy, animal-based proteins are the only complete proteins, delivering all of the essential amino acids you need in sufficient amounts.

Plant-based proteins offer different types and amounts of essential amino acids and, as such, are considered incomplete proteins. Vegans and vegetarians must rely on a variety of plant-based proteins to ensure they get all nine essential amino acids.

For example, grains are low in the amino acid lysine, while beans and nuts are low in methionine. When grains and legumes are combined (such as rice and beans or peanut butter on whole-wheat bread), they form a complete complementary protein.

A Word From Verywell

If you have PCOS and struggle with weight or blood sugar control, don't simply gorge on proteins and cut out all carbs. You're more likely to do yourself more harm than good. Instead, work with a doctor or dietitian to find the high-protein diet that is not only appropriate for your age, weight, and medical condition but you can sustain over the long term.

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