The keto diet is popular among people looking to shed pounds. But the question remains: Is keto diet safe in the long-term? Here, what researchers and doctors want you to know.

What is the keto diet?

The ketogenic (keto) diet is a high-fat, low-calorie diet. People following the keto diet aim to eat 75 percent of their calories from fat, 20 percent from protein, and 5 percent from carbohydrates. If you’re curious about the plan, check out these before-and-after keto diet pictures. The keto diet has been used for decades to help children with certain types of epilepsy avoid seizures—and research backs up the continuous use in these people.

What about everyone else: Is keto diet safe in the long term?

How long the keto diet is safe for weight loss is still under study. Early research found that overweight individuals who followed it for 24 weeks had positive results. Another study recommends people follow the diet for no more than 12 months. Even during that time, say the authors, “close monitoring of [kidney] functions while on a ketogenic diet is imperative.” In other words, let your doctor know what you’re up to, and keep an eye on your kidney health. Beyond a year, no one’s really sure how safe the diet is.

“My professional recommended period of following the keto diet is about six months maximum, and that will also depend on how much the person weighed prior to starting the diet and the state of his or her overall health within those six months,” says Nikola Djordjevic, MD, of MedAlertHelp.org.

He adds, “That said, I highly advise that anyone on the keto diet get checked by a professional nutritionist or a medical doctor regularly to make sure he or she hasn’t developed any complications like hypertension.”

Precautions to take with long-term keto dieting

Despite all the keto success stories, most doctors still warn against the plan—in part because U.S. News & World Report ranked it as one of the worst diets. Doctors who do support keto say there are rules and guidelines that are more likely to keep the diet effective and healthy, starting with:

Focus on quality fats

“Since the largest component of a keto diet is fat, my biggest concern with keto is that the fats consumed may not be healthy ones,” says Alvin Berger, MS, PhD, adjunct professor of nutrition at the University of Minnesota and CEO of SciaEssentials. “Examples of undesirable fats include excessive amounts of coconut oil, deep-fried fats, lard, and oxidized/rancid fats.” Dr. Berger suggests you work with a certified nutritionist, particularly one with an expertise in fats, to hone your keto diet for the long term.

Don’t waste your carbs

Keto eaters find a lot of “low-carb” hacks for their favorite non-keto foods, from chocolate chip cookies to baked bread, but Dr. Berger says you should use the carbs you can consume on healthier options, like vegetables.

Pay attention to micronutrients

Keto dieters can miss out on some key nutrients like electrolytes such as sodium and potassium, says Jennifer Mason, MS RD, a dietitian who specializes in low-carb and keto diets. Without adequate sources of these two nutrients, you may experience nausea, weakness, muscle cramps, and constipation—or the keto flu. You can try supplements, or focus on nutrient-rich foods that will provide you what you need.

Eat real food

Your pharmacy shelves are groaning under the weight of keto supplements, but Adam Nally, DO, author of The Keto Cure, advises steering clear. “I recommend using real food instead of protein powders and MCT oil,” he says. “Adequate nutrients in a ketogenic diet come from eating real animal protein and real animal fat over the long term.” If you are considering keto supplements, review this list of the keto supplements that might be worth your money.