This Is How to Follow the Keto Diet, Explained in 2 Minutes

You might actually need a doctor’s note before starting this diet.

Loading the player...

If you’ve recently visited the cookbook section of Barnes & Noble, you’ve definitely seen the explosion of books for a “keto” or “ketogenic” diet. The books are packed with recipes that allegedly help you burn fat, lose weight, and “reset” your digestion.

What the Heck Is the Keto Diet?

The keto diet has taken on a new life recently with a ton of fanfare on social media, but originally it was used a treatment for children with severe epilepsy, a neurological condition that causes seizures. Here’s how it came about: Back in the fifth century BC, the Greek physician Hippocrates noticed that fasting appeared to be effective at reducing seizures. Indeed, this finding was repeated successfully in the centuries to come. When medication failed, fasting succeeded for many patients (but not all).

Normally, your body gets energy from converting food to glucose, which mostly comes from your carbohydrate intake. When you’re not eating, the body uses fat for fuel instead; that’s called a state of ketosis. It appears that entering this state of ketosis can help stave off seizures for some epilepsy patients.

There’s just one problem: You can’t fast 24/7. In the 1910s and ’20s, scientists began to study why the “ketosis” of starvation was so effective, and how it could be implemented safely and long-term. Although many researchers investigated, it was ultimately Dr. Russell Wilder of the Mayo Clinic who coined the term ketogenic diet, according to professor of pediatric neurology James W. Wheless, MD, in the book Epilepsy and the Ketogenic Diet.

In Dr. Wilder’s research, he noted that you can mimic the state of starvation by depriving the body of carbohydrates, thus reducing glucose and forcing the body to turn to fat for energy. By eating a high-fat diet void of carbs, patients with epilepsy could replicate a fasting state and maintain it for a longer period of time.

Thus, the keto diet, as defined by the Mayo Clinic in 1924, is a low-carb, normal-protein, high-fat diet. It’s very low in carbs. We’re talking 10 to 15 grams of carbs per day, according to Wheless. That amounts to half an apple. That’s it. No more carbs for the day.

So… how on earth did it become the new hot weight-loss diet? You’re probably familiar with keto’s cousin, the Atkins Diet. This weight-loss diet from the mid-2000s begins with just 20 grams of carbs a day and was based on the keto model. Marketed for quick weight loss, the extremely low-carb approach became linked to weight loss instead of seizure treatment.

What Can You Eat on the Keto Diet?

“In order to achieve nutritional ketosis, a person’s macronutrient profile should be close to the following: 70 to 80 percent fat, 15 to 20 percent protein, and five to 10 percent carbs,” explains Catherine Metzgar, PhD, RD, of Virta Health, a type 2 diabetes clinic.   

Here’s what that might look like on the plate:

  • Full-fat dairy products

  • Eggs and mayo

  • Minimally processed meats and seafood

  • Non-starchy vegetables

  • Low-sugar fruits like berries, avocado, and olives

  • Olive oil and other oils

  • Nuts

So What *Can’t* You Eat on the Keto Diet?

Good question. Carbs show up in a wide variety of foods, and these carb-dense items would be off-limits on the keto diet:

  • Grains, breads, and cereals

  • Legumes

  • Most fruit

  • Starchy vegetables, like potatoes and corn

  • Desserts, candies, and other sweets

Since so few carbohydrates are allowed on the keto diet, this doesn’t allow for much leeway. In fact, even one cup of whole milk supplies 12 grams of carbohydrates, so there’s really not much room to splurge on carby items (e.g. a morning bagel).

What Are the Benefits of the Keto Diet?

Here’s where the controversy lies. Some people (including the authors of the keto cookbooks) tout a variety of benefits of going keto. Small-scale studies have found some evidence that the keto diet could aid in weight loss, blood sugar management, insulin sensitivity, and cholesterol, according to Grace Derocha, RD, CDE, certified diabetes educator and health coach at Blue Cross Blue Shield of Michigan.

“These shorter-termed studies show some potential benefits of the ketogenic diet,” says Derocha. “However, there needs to be more research done to indicate if there are longer-term benefits.”

At the end of the day, the keto diet is a medical approach for helping to manage seizures. Any other purported benefits need additional research.

What are the Cons of the Keto Diet?

Logistically speaking, the keto diet is a tough one to follow: It requires strict compliance or ketosis won’t happen. Although rapid weight loss is possible, it’s not an easily sustainable diet and can lead to yo-yo dieting.

“[The keto diet] can be challenging to follow correctly and also comes along with some potential health hazards,” says Ginger Hultin, MS, RDN, CSO, Seattle-based registered dietitian and health coach at Arivale. “It may not be a diet that many people can, or want to, follow for general health or weight management.”

Those potential health hazards? Well, it would be tough to meet certain nutritional requirements, such as the recommended 25 grams of daily fiber, without adequate fruits and grains. This can lead to constipation and other digestive issues. (Learn more habits that affect your bowel movements.)

The keto diet has also been linked to a higher risk of kidney damage. A study in the Journal of Child Neurology found that one in 20 children following the keto diet for epilepsy developed kidney stones, which are usually rare in children. This may be due to the large volume of animal protein consumed on the keto diet, according to the National Institute of Digestive and Kidney Diseases. (Find out more facts about the kidneys here.)

And then there’s the keto flu. It can take some adjustment for the body to shift to using fat for fuel, and that transition time will be, um, kinda miserable. After all, this diet is meant to mimic fasting. Until your body adjusts, you may experience flu-like symptoms, such as “dizziness, brain fog, irritability, nausea, and muscle soreness,” says Derocha.

Should You Try the Keto Diet?

Do you have seizure-causing epilepsy that medications have been unable to treat? If so, then you and your physician might discuss the possibility of trying the keto diet under medical supervision.

Otherwise, you might want to pass on this fad. “A healthy balanced diet is a better option compared to a strict ketogenic diet,” says Derocha, noting that the keto diet cuts out well-known healthful foods like fruits, whole grains, and beans. “I always encourage my patients to have a healthy relationship with food and eat a balanced diet for their best health.”

For a diet with proven, long-term health benefits, check out how to eat a Mediterranean diet.