Despite the millions of Americans who go on a diet each year, obesity rates are higher than ever thanks, in part, to lifestyle. In Wisconsin, only 50% of adults meet the state’s physical activity recommendation of at least two-and-a-half hours of aerobic activity each week, and only one in six adults eat five or more fruits and vegetables each day. Habits like these may contribute to a 32% obesity rate, ranking Wisconsin the 21st most obese state in the United States.

Given these numbers, many people are looking for ways to lose weight quickly and easily. In recent years, the ketogenic diet (also known as the “keto diet”) has become all the rage, partly because it promises such fast results. While it may be trendy, it’s important to know just what the keto diet is before jumping onto another health bandwagon.

What is a “ketogenic” diet?

The human body uses glucose, derived from carbohydrates in the diet, as its main source of energy. Fat is the body’s second option. When the body burns fat, it uses these products and converts them into ketone bodies, another fuel source for the body’s organs and tissues. This is called ketosis and is a process that usually only occurs during times of starvation or fasting, when the body needs to use its fat stores.

There is no standard keto diet for weight loss. A ketogenic diet restricts carbohydrate consumption usually to less than 50 grams per day. A typical keto diet may call for 5% of total calories from carbs, 20% from protein and around 70% from fat. Meanwhile, the Dietary Guidelines for Americans recommends a diet made up of 45-65% carbs, 15% protein, and 20-30% fat.

Ketogenic diets have been used to treat epilepsy since the 1920s. Studies have shown that the diet can be effective in some patients whose seizures do not respond to medications. The University of Wisconsin Hospitals and Clinics uses nutrition therapy to treat epilepsy with individualized ketogenic diets. A registered dietitian provides nutrition education and counseling for patients with epilepsy.

How might the keto diet help with weight loss, and how is it problematic?

Doctors and nutritionists don’t know all the ways the keto diet works, but it seems to suppress appetite and burn more of the fat that the body already has stored. Evidence is conflicting, as some studies have shown that weight loss on a ketogenic diet is greater for some people than weight loss on a conventional diet during the first six months, but have found no differences in weight loss at one year. Other studies have demonstrated maintained weight loss at one year, but the long-term implications of a ketogenic diet are still unknown.

A very low carb diet may assist with quick weight loss, but much of that is water weight. There are also initial side effects, including nausea, headaches and fatigue.

Longer term, a lack of enough fruits, vegetables and whole grains means a ketogenic diet will be low in important vitamins, minerals and fiber. This may lead to its own short- and long-term health problems.

Because the keto diet isn’t more effective at providing long-term weight loss than a typical healthy diet and routine exercise, most people would be better off managing weight by following the U.S. dietary guidelines, paying attention to portion sizes and increasing physical activity. The keto diet may be more promising for people with certain medical conditions than for weight loss in the general population.

Finally, anyone considering a special diet should first talk to a healthcare provider.