Cutting back on carbohydrates is nothing new. At the height of the Atkins craze in the early 2000s, a Gallup poll found that 27 percent of Americans said they were avoiding carbohydrates. And while Atkins still has its devotees, other low-carbohydrate plans, like Paleo, are getting more attention these days. The latest popular low-carb approach is the Ketogenic diet, a very low-carbohydrate, high-fat, moderate-protein plan. The premise: Cut back on carbohydrates and sugars so that the body burns fat for fuel instead of carbs (its preferred source) in a metabolic state called ketosis.

Do Low-Carb Diets Work?

People lost more weight and even improved their cholesterol more on a low-carb diet (defined as fewer than 40 grams of carbohydrates per day) compared with those on a low-fat diet, according to research published in the Annals of Internal Medicine from Tulane University. And a 2017 study published in the Journal of Medical Internet Research found that overweight adults with type 2 diabetes lost more weight and improved their blood sugar more on a ketogenic diet than on a conventional low-fat diabetes plan.

The Upside

Eating fewer carbs and more protein may help to rein in your blood sugar—meaning, for most people, less hunger and cravings. “Low-carb diets make it a little bit easier to cut the calories and not be starving; they’re easier to stick to,” says Lawrence Cheskin, M.D., director of the Johns Hopkins Weight Management Center in Baltimore. A ketogenic diet where most of the calories come from fat may drive up hunger initially, however, once that feeling subsides after about three weeks in, hunger levels decrease—along with weight—according to a 2017 study from Norway published in the International Journal of Obesity. 

The Downside

Revert back to non-ketogenic eating after a period of time on the plan, according to the same Norwegian study, and feelings of hunger are likely to bounce back. The whole grains, legumes, and fruit that many people cut back on while on a low-carb diet are loaded with filling fiber and are consistently linked with decreased rates of heart disease, diabetes, and more.

Cheskin notes that people with type 1 (insulin-dependent diabetes) should not follow a ketogenic diet. What’s more, overdoing certain fat and protein sources can be problematic for many people. “Some observational studies have found that people who consumed a diet with high amounts of animal protein and fat—mostly from red and processed meats—and relatively low amounts of carbs had increased risk of cardiovascular disease and mortality,” said Frank Hu, M.D., Ph.D., chair of the nutrition department at Harvard T.H. Chan School of Public Health in Boston.

Too much protein can also worsen kidney function in people who have kidney disease, which affects more than 30 million people in the U.S., most of whom don't know they have it, according to the National Kidney Foundation. People at risk for kidney problems include those with diabetes and high blood pressure.

The Middle Ground

Trim excess carbs, particularly sugars and other refined carbs such as white flour and white rice, to cut back on calories. Include protein from sources like beans, fish, lean meats and poultry, and nuts and seeds in meals and snacks to help boost satisfaction.