Everything You Need to Know About the Ketogenic Diet

This article is not meant to diagnose or provide medical advice—that responsibility lies with physicians. The author is not a licensed medical professional.

Cutting carbs has long been considered a key to weight loss, just look at the Atkins and South Beach diets. The newest in the low-carb craze is the ketogenic diet.

The ketogenic diet arose about a century ago as a way to treat children with epilepsy, but recently, it’s been revived and retooled as a method for weight loss.

While many versions of the diet exist, the basic idea is that by severely restricting carbohydrates and boosting fats, the body enters into a state of ketosis, so that instead of burning sugar and carbohydrates for fuel, it uses fat.

But getting to ketosis is tough. Under many versions of the diet, daily carbohydrate intake can’t exceed 20 grams—the equivalent of a little more than one apple. So in addition to cutting starches such as bread, pasta and rice, followers of the diet also have to eliminate fruit and some vegetables, and instead rely on meat, poultry, fish and high-fat dairy products.

The Benefits

Adhering to a “real food” version of the ketogenic diet—consuming foods such as meat, fish, eggs, cream, butter and vegetables—is an effective way to lose weight, according to Eric Westman, M.D., MHS, director of the Duke Lifestyle Medicine Clinic.

“You basically use for energy what you eat,” said Dr. Westman. “If you’re eating lots of carbohydrates, you’re going to burn them for energy. If you’re eating fat and not carbohydrates, you’re going to be burning fat for your energy.”

Following the ketogenic diet, Westman explained, can aid in weight loss and managing diabetes—results that are backed by science. “It’s now one of the most studied diets ever,” he said. “Since 2002, there have probably been 50 to 75 papers, the longest one over two years. The best way to say it is that there’s as much evidence for this kind of diet as there is for any kind of diet.”

Dr. Westman has also seen the same positive results in his own clinical work. “In the short run, I can ‘fix’—meaning put in remission—someone’s diabetes in just a few weeks even if they’ve had it for years,” he said. In addition, he explained, pre-clinical science has pointed to the possibility that the diet may also be helpful to patients with Alzheimer’s disease and certain types of cancer.

Meanwhile, the effectiveness of low-fat diets hasn’t been proven, according to Dr. Westman. “The low-fat diet was actually tested among about 50,000 women for eight years,” he said. “And the low-fat diet didn’t help with anything.”

But Dr. Westman said more research is needed into the specifics of the ketogenic diet to better understand the optimal ratio of macronutrients—fat, protein and carbohydrates—a person should consume. “While everyone thinks they know what the right number is, I don’t think anyone really knows,” he said. “When I use this diet in a clinical setting, I allow people to choose their own foods within a range of certain foods, and not really fine-tune the macronutrient mix at all.”

The Drawbacks

Photo by Tim Boyle/Getty

While the ketogenic diet can aid in weight loss, it may not be nutritionally sound, said Jim White, RDN, owner of Jim White Fitness and Nutrition Studios in Virginia Beach.

“It really almost avoids three food groups,” he said of grains, dairy, and fruits and vegetables. “Those are some major foods that can help to decrease cholesterol, decrease the risk of cancer and help improve the body.”

The carbohydrates that are severely restricted under the ketogenic diet are an important macronutrient, said White. While reducing added sugars and highly processed carbohydrates is helpful, he explained, eliminating nutritious carbohydrates can deprive the body of the energy it needs to function properly.

White also hesitates to recommend a diet that restricts fruits and vegetables, since most Americans struggle to eat the recommended five servings per day. “Before we make all these other suggestions, just getting them to eat fruits and vegetables is a big goal,” he said. “Studies show that fruits and vegetables, grains and dairy products help you lose weight and give you nutrients for vitality. I never have people come to my clinic and say they’re obese because they eat too much fruit.”

And he doubts the long-term viability of extreme eating regimens. “If you look at a lot of the studies, not just ketogenic, many of the diets are effective for a 12-week span, but longevity is very challenging,” he said. “Most people end up starting to eat carbs again and it knocks them out of ketosis, and they end up right back where they were.”

Instead, White recommends a more balanced approach of about 50 percent carbohydrates, 20 percent protein and 30 percent fat. “If we start neglecting one of these, we’re out of balance and we’re not getting the nutrients we need,” he said.

Tips and Tricks

For Maria Emmerich, author of several ketogenic cookbooks including Quick & Easy Ketogenic Cooking: Meal Plans and Time Saving Paleo Recipes to Inspire Health and Shed Weight, eating this way doesn’t have to mean giving up favorite foods.

“I love food, so I recreate my and everyone’s favorite dishes into ketogenic dishes,” she said. “If you don’t mind spending a little time in the kitchen or being creative, it definitely can become a lifestyle.”

Emmerich replaces starches with cauliflower rice (which she said can be made from scratch or even found pre-made in some grocery stores), zucchini or cabbage noodles and baked avocado “fries” wrapped in bacon. Some of her go-to homemade dinners include pizza with a zucchini or almond flour crust and skillet lasagna.

Eating out is where many people slip up on the diet, she said. But it’s not impossible. At brunch, instead of French toast, order an omelet or salmon, eggs and hollandaise sauce. For lunch or dinner, try a burger with a side salad instead of a bun, but be wary of condiments like ketchup, which are full of sugar.

Even dessert using alternative sweeteners such as Stevia isn’t off limits. One of Emmerich’s favorites is a flourless chocolate torte, which she always keeps on-hand in her freezer, and push pops made of heavy cream, unsweetened almond milk and avocado.

“I learned to have desserts at home,” she said. “Prepping ahead helps you to say no when the dessert is staring at you in the face.”

Caitlin Yoshiko Kandil is a journalist based in Southern California who covers social issues, culture, food and health.