Ketogenic diets have become incredibly popular. Early research suggests this high-fat, very low-carb diet may benefit several health conditions. Although some of the evidence is from case studies and animal research, results from human controlled studies are also promising.
1. Metabolic Syndrome
Metabolic syndrome, sometimes referred to as prediabetes, is characterized by insulin resistance. You can be diagnosed with metabolic syndrome if you meet any 3 of these criteria:
- Large waistline: 35 inches (89 cm) or higher in women and 40 inches (102 cm) or higher in men.
- Elevated triglycerides: 150 mg/dl (1.7 mmol/L) or higher.
- Low HDL cholesterol: Less than 40 mg/dL (1.04 mmol/L) in men and less than 50 mg/dL (1.3 mmol/L) in women.
- High blood pressure: 130/85 mm Hg or higher.
- Elevated fasting blood sugar: 100 mg/dL (5.6 mmol/L) or higher.
People with metabolic syndrome are at increased risk of diabetes, heart disease and other serious disorders related to insulin resistance. Fortunately, following a ketogenic diet may improve many features of metabolic syndrome. Improvements may include better cholesterol values, as well as reduced blood sugar and blood pressure. In a controlled 12-week study, people with metabolic syndrome on a calorie-restricted ketogenic diet lost 14% of their body fat. They decreased triglycerides by more than 50% and experienced several other improvements in health markers.
Glycogen Storage Disease
People with glycogen storage disease (GSD) lack one of the enzymes involved in storing glucose (blood sugar) as glycogen or breaking glycogen down into glucose. There are several types of GSD, each based on the enzyme that is missing. Typically, this disease is diagnosed in childhood. Symptoms vary depending on the type of GSD, and may include poor growth, fatigue, low blood sugar, muscle cramps and an enlarged liver. GSD patients are often advised to consume high-carb foods at frequent intervals so glucose is always available to the body.
However, early research suggests that a ketogenic diet may benefit people with some forms of GSD. For example, GSD III, also known as Forbes-Cori disease, affects the liver and muscles. Ketogenic diets may help relieve symptoms by providing ketones that can be used as an alternate fuel source. GSD V, also known as McArdle disease, affects the muscles and is characterized by a limited ability to exercise.
In one case, a man with GSD V followed a ketogenic diet for one year. Depending on the level of exertion required, he experienced a dramatic 3- to 10-fold increase in exercise tolerance. However, controlled studies are needed to confirm the potential benefits of ketogenic diet therapy in people with glycogen storage disease.
Polycystic Ovary Syndrome (PCOS)
Polycystic ovary syndrome (PCOS) is a disease marked by hormonal dysfunction that often results in irregular periods and infertility. One of its hallmarks is insulin resistance, and many women with PCOS are obese and have a hard time losing weight. Women with PCOS are also at an increased risk for type 2 diabetes. Those who meet the criteria for metabolic syndrome tend to have symptoms that affect their appearance. Effects may include increased facial hair, acne and other signs of masculinity related to higher testosterone levels.
A lot of anecdotal evidence can be found online. However, only a few published studies confirm the benefits of low-carb and ketogenic diets for PCOS. In a 6-month study of eleven women with PCOS following a ketogenic diet, weight loss averaged 12%. Fasting insulin also declined by 54% and reproductive hormone levels improved. Two women suffering from infertility became pregnant.
People with diabetes often experience impressive reductions in blood sugar levels on a ketogenic diet. This is true of both type 1 and type 2 diabetes. Indeed, dozens of controlled studies show that a very low-carb diet helps control blood sugar and may also provide other health benefits.
In a 16-week study, 17 of 21 people on a ketogenic diet were able to discontinue or decrease diabetes medication dosage. Study participants also lost an average of 19 pounds (8.7 kg) and reduced their waist size, triglycerides and blood pressure. In a 3-month study comparing a ketogenic diet to a moderate-carb diet, people in the ketogenic group averaged a 0.6% decrease in HbA1c. 12% of participants achieved an HbA1c below 5.7%, which is considered normal.
Epilepsy is a disease that causes seizures due to excessive brain activity. Anti-seizure medications are effective for some people with epilepsy. However, others don’t respond to the drugs or can’t tolerate their side effects. Of all the conditions that may benefit from a ketogenic diet, epilepsy has by far the most evidence supporting it. In fact, there are several dozen studies on the topic.
Research shows that seizures typically improve in about 50% of epilepsy patients who follow the classic ketogenic diet. This is also known as a 4:1 ketogenic diet because it provides 4 times as much fat as protein and carbs combined. The modified Atkins diet (MAD) is based on a considerably less restrictive 1:1 ratio of fat to protein and carbs. It has been shown to be equally effective for seizure control in most adults and children older than two years of age.
The ketogenic diet may also have benefits on the brain beyond seizure control. For example, when researchers examined the brain activity of children with epilepsy, they found improvements in various brain patterns in 65% of those following a ketogenic diet — regardless of whether they had fewer seizures.