Should You Try the Keto Diet? These Dietitians Weigh In on the Food Fad

By now you’ve probably heard friends talking about the Keto Diet (or ketogenic diet), a high-fat, no-carb diet that supposedly helps the body burn through its fat to provide energy. But is the diet right for you? Let’s take a closer look.

What is the Keto Diet?

The Keto Diet states that 75% of a person’s food should be high in fat, 20% should be protein and less than 5% should be carbohydrates. It basically cuts nearly all carbohydrates from a person’s eating so that they’re pushed into “ketosis,” a bodily state in which blood sugar (insulin) levels drop and the body starts burning fat rather than sugar as its primary energy source.

But it often takes the body three to four days to start using fat-based ketones rather than carb-based glycogens as its energy source. During that transitional time, people can feel wiped out, lightheaded, nauseated, mentally fogged or experience cramps or headaches (something often referred to as the “keto flu”).

But the “flu” is said to lift within a few days. Because carbohydrate reserves within bodily tissues store lots of water, the Keto Diet causes people to shed “water weight” quickly, adding to its reputation as a quick weight-loss diet.

What do dietitians think of the Keto Diet?

The ketogenic diet isn’t a new fad. A variation of it has been used since the 1920s to treat childhood epilepsy. (In fact, some studies show it can also reduce symptoms of other neurological illnesses.) It’s also quite similar to the 1973 Atkins Diet or the 2000 French-based Dukan Diet.

But registered dietician Kristin Kirkpatrick says it’s not always an easy diet to stick to, especially when you’re traveling and in less control of your food sources. She adds that it can also cause constipation in some people because it largely cuts out fiber that’s often found in carbohydrates.

Another dietician, Toby Amidor, says because it relies so heavily on fat, Keto dieters often need to take vitamin supplements to ensure they’re getting other micronutrients the body needs.

U.S. News and World’s panel of nutritionists and specialists in diabetes and heart disease ranked the Keto Diet with two out of five stars. The panel said it was unsafe for people with diabetes and can potentially encourage heart disease with its high-fat ingestion, though others contend it can encourage consumption of healthy fats and oils.

Finally, Maria Zamarripa, another registered dietitian, doesn’t recommend the Keto Diet for the general public, particularly because it obsesses too heavily on cutting carbs and restricting food choices and partly because there hasn’t been a lot of research about its long-term effects.

Instead, she suggests getting a nutritious mix of foods so you have more eating options and less potentially problematic monitoring of what you eat.