Friend or Fad: Are These Trendy Diets Good for You?
Registered dietitian Lisa Muras weighs in on the pros and cons of five popular food regimens.
The Keto Diet
What is it?
The ketogenic, or Keto diet, has been around for almost 100 years. It was originally used to reduce the severity of seizures in young patients with epilepsy. The diet promotes a high fat intake, with fat accounting for 65 to 80 percent of daily calories, while protein makes up 15 to 25 percent, and carbohydrates are restricted to just 5 to 15 percent. That’s only about 20 to 50 grams of carbs per day (compared with the average amount of 245 grams), or no more than 1/2 to 1 cup of rice per day. The idea is to put the body into ketosis—the burning of fat instead of glucose for fuel. Normally, the human body uses glucose as its primary energy source, but when carbohydrates—which turn into glucose or sugar—are severely restricted, the body then uses fat for energy and produces ketones as a byproduct. In a truly ketogenic diet, individuals would be checking their urine for the presence of ketones to make sure they are using fat as their main energy source.
The ketogenic diet reduces insulin secretion and some research indicates it is an effective tool for lowering blood sugar in people with diabetes. One recent study involving subjects with diabetes who followed a ketogenic diet found some participants lowered their hemoglobin A1c (average blood sugar over a three-month period) to target levels and a loss of 12 percent of their body weight. Besides experiencing reduced blood glucose, individuals following the Keto diet report decreased cravings and hunger. It isn’t clear if this is the result of increased satiety from the high levels of fat, or because of the actual ketones. In the short term, it appears effective for weight loss.
There are no long-term studies on the ketogenic diet for weight loss or blood sugar control. Some research suggests that participants may lose weight, but typically gain it back once they stop the diet. Furthermore, there is no standard Keto diet. The recommended carbohydrate intake varies, so it can be difficult to compare results. Nutrient deficiencies are also a concern, including potassium (found in vegetables such as potatoes, fruits and beans), B vitamins, fiber and prebiotics, which aid the growth of beneficial microorganisms for better gut health. Some studies have tied the Keto approach to an elevation in LDL (“bad”) cholesterol and triglycerides—so if you’re using saturated fats such as butter, cream and animal fats as your primary fat source, you could be at increased risk for cardiovascular disease. And as with other trendy diets, restricting carbohydrates can be hard to stay with over time.
Some aspects of the Keto diet can be beneficial. Since carbohydrates typically make up 50 percent of our calories, consuming less of them can help with weight loss, and most people will see health benefits when avoiding refined carbs such as desserts, potato chips or pizza. However, it’s best not to eliminate slow-digesting carbs such as fruit, legumes and whole grains.