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by Sarah Koszyk RDN

February 11, 2019

The low-carb, high-fat diet has become popular

The ketogenic diet has become popular of late, but there are some things you should consider before deciding whether to try it.

The low-carbohydrate, high-fat diet puts the body into a metabolic state called ketosis, in which the body produces ketones and burns fat instead of carbs for energy. Ketosis can be dangerous when too many ketones build up in your body. High levels can lead to dehydration and change your blood’s chemical balance. However, a steady state of ketosis can make you feel less hungry and may help maintain muscle mass.

Your body will need about two to four days of consuming very low amounts of carbs, such as 20 to 50 grams per day, to start burning fat for energy. People who choose to follow the keto diet need to strictly adhere to it to get fat-burning results.

The keto diet primarily consists of butter, cheeses, eggs, fish, meats, nuts, oils, seeds, and fibrous, nonstarchy vegetables. Foods high in starches, such as corn, peas, potatoes, and pumpkin, aren’t part of the keto diet.

The Good

High-fat, low-carb diets with lots of protein have been shown to prevent seizures for people with epilepsy. Some research suggests that keto diets might help people with Type 2 diabetes and insulin resistance. Keto diets also have been suggested to lower the risk of heart disease.

“Swimmers trying to lose weight may find they lose weight following a keto diet because fat, along with protein, may provide a more satiating effect, which can result in eating less,” says Leslie Bonci, a registered dietitian and sports nutritionist in Pittsburgh.

Amy Stephens, a registered dietitian and sports nutritionist in New York City, says: “If an endurance swimmer trains at low intensity (70 percent of his or her maximum heart rate), the body will mostly rely on fat for energy. Therefore, the keto diet can be effective.”

The Bad

A study published in Frontiers in Physiology in 2017 suggested that ingestion of ketones by elite professional cyclists impaired their performance. The cyclists also experienced gut discomfort ranging from mild to severe.

“Other studies have suggested no positive impact on performance from a high-fat, low-carb diet, even when protein intake is adequate,” Bonci says. “Low-carb diets can suppress some markers of protein synthesis and a potential reduction in high-energy performance. This results in less energy to go all out in a race.”

Stephens says: “Many swimmers report not having that last burst of energy in order to reach the finish. In a sport like swimming, every hundredth of a second can mean a win or a loss, which can be a significant disadvantage.”

Should You Try It?

Stephens recommends that people on the ketogenic diet stick to it while training, so their body has time to adjust. Bonci says that athletes should incorporate some carbs before and after a workout, such as eating a slice of whole grain toast with an avocado before and some Greek yogurt with nuts and berries after.

The keto diet, which hasn’t had much research done on its longterm effects, is very hard to stick to. Before trying any new diet, you should remember that evidence shows a well-balanced diet full of fruits and vegetables of various colors, whole grains, lean proteins, heart-healthy fats, and lots of water is the best nutrition plan for living a long, healthy, active life.


  • Health and Nutrition


  • Diets
  • Health
  • Nutrition