The Keto Craze: Does the Diet Live Up to the Hype?

First and foremost, the keto diet mimics the metabolic effects of fasting by forcing your body to use fat instead of carbs as its primary source of energy. That process — tricking your body to burn fat for energy by turning it into ketones — is called ketogenesis. When your body has ketones in the blood stream, then you are in a ketosis. That means your body's energy is coming from those ketone bodies in your blood, rather than blood glucose.

You'd think burning fat would be a great way to lose weight, but doing it this way can be problematic. For instance, Robert Atkins, M.D., used a variation of the ketogenic diet to manage his own weight and later turned it into the Atkins diet. His book "The Atkins Diet Revolution", which was first published in 1972, helped launch the low-carb diet craze. The Atkins diet is a modified version of the keto diet, and promotes a high-protein plan that phases in carbs. The first phases allows only 20 to 25 grams a day and each phase after gradually increases the amount of carbs to a max of no more than 100 grams of per day.

The Atkins diet approach is controversial because some use the diet to indulge in fatty foods like bacon and cheese, and the diet discourages people from eating vegetables, fruits and beans, which provide valuable vitamins, fiber and other nutrients.

"We always phase through different fad diets. Social media is definitely a channel for these fad diets to spread," says Kristen Smith, M.S., R.D., spokesperson for the Academy of Nutrition and Dietetics. "People are always looking for the next best, greatest diet, and seeing others do it led people to try the keto diet. Structured plans (like a keto diet) are viewed as easier options for chronic dieters."

When it comes to weight loss, keto diets focus on burning fat rather than carbs. Typically, carbohydrates are the body's primary fuel source. On a keto diet, fat becomes the primary fuel source.

But, going keto isn't for everyone. Cutting carbs to 20 grams a day is hard for many people; our brains alone need 120 grams of carbs to function, and the U.S. Dietary Guidelines for Americans recommends 130 grams of carbs daily. (To give you an idea of what 20 grams of carbs is, one small banana has 23 grams.)

Reducing your carb intake so drastically means foods like pasta, bread, rice, and even some fruits and vegetables like beans, peas, corn, potatoes and onions, are out. Some of these are also rich in fiber, so eliminating them from your diet could cause constipation. Because the brain prefers carbs for energy, a ketogenic diet could make you irritable and moody, cause headaches, or make you feel like you have brain fog.

One of the other dangers is having too many ketone bodies in your blood, which can happen after being on a ketogenic diet too long, or if your body doesn't produce enough insulin to restrict the ketones. The excess causes ketoacidosis, which is toxic.

And, of course, another danger is the diet can be high in saturated fat. "The diet focuses largely on fatty foods, and the increased amount of saturated fat can be harmful," Smith says. "Diets high in saturated fat are linked to heart disease."

Smith recommends that anyone on keto diet get medical supervision. "It really depends on the person as to whether they can do it for a longer time," she says. "It's important to have medical supervision [if you do it]. The rapid weight loss requires someone to monitor your labs and make medication adjustments." For example, if you have high blood pressure or diabetes — or are losing weight rapidly — you may need medications adjusted.

Because going keto is hard, not many people can stick to it long-term, and so Smith recommends finding another a diet plan you can live with. "When you're trying to lose weight, restricted diets can offer rapid weight loss, but they're not long-term solutions for a healthy weight," she says. Instead she suggests making dietary and physical activity changes that you can do for life. "That will give you a better chance of keeping the weight off for the long haul ... and avoid the yo-yo effect of weight loss."