Low-carb diets are nothing new. The new millennium ushered in the Atkins diet craze, followed by the South Beach diet, which became a favorite among celebrities.

The ketogenic diet might seem like the latest instalment in a long line of low-carb fad diets. But don’t be fooled—this increasingly popular diet has actually been around for just shy of a century. First used to treat children with epilepsy, it was developed by a doctor in the 1920s.

These days, keto is seeing a revival. The benefits? Weight loss, for one. But aside from its fat-burning properties, it’s also been touted as an effective diabetes management tool, since it minimizes carbs.

Though long-term studies into the diet’s risks and benefits are limited, keto may also reduce the risk of cardiovascular disease, aid the treatment of certain types of cancer, and combat symptoms of Alzheimer’s disease.

Breaking Down the Keto Diet

The keto diet is a low-to-no carb diet. Keto dieters track their “macros,” or macronutrients, to make sure they’re getting most of their calories from fat (60-75 percent), some of their calories from protein (15-30 percent), and very few of their calories from carbohydrates (5-10 percent).

On the plate, the emphasis is on meat, fish, cheese, butter, cream, and low-carb veggies such as cabbage, cauliflower, or salad greens. Carb consumption is capped at a maximum of 20 grams per day. That’s just a little bit more than an apple.

There are no restrictions on how many calories keto dieters can consume in a day. The focus is on listening to when you feel hungry or full, though high-fat foods are said to improve satiety.

Keto Works by Co-Opting Your Body’s “Fasting” Mechanism

In a normal diet, carbs are the main energy source. However, when you deprive your body of carbs, it goes into fasting mode, even if you continue to take in fat and protein.

This process is called ketosis, and it causes ketone molecules to build up in the bloodstream. As blood sugar levels plummet, the body starts to break down fat and use it as energy. Hence, the fat burn.

Though ketosis is actually a mild form of ketoacidosis, a condition that affects type 1 diabetics, most experts say that ketosis isn’t necessarily dangerous.

But That Doesn’t Mean It’s 100 Percent Healthy

Like every diet, keto has its advantages and its challenges. The most obvious? It’s hard to cut out carbs indefinitely, and dinner parties or eating out with friends are likely to present a problem. Others find that without carbs — imagine giving up grains, cutting down on wine, avoiding all tropical fruit — their diet becomes bland and boring.

But experts say there are other, more serious risks. For one, clinical reviews show that the keto diet is less-than-effective in the long term, a downside that’s rarely mentioned by self-professed keto dieters.

Some experts suggest that most of the weight loss is actually water weight, and that keto can also lead to exhaustion and muscle loss. Other doctors believe that keto is an “extreme” diet that’s only safe under clinical supervision. According to Francine Blintin, R.D., a clinical nutritionist, the diet can “do more harm than good.”

The bottom line? Like most fad diets, this one may help you shed a few pounds fast. But it likely isn’t sustainable in the long term.

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