What is the keto diet?

Follow along on social media and you might see posts or pins promoting a “keto diet”. From recipes for "fat bombs" to nutritional supplements on store shelves, the ketogenic diet continues to gain popularity as a way to burn fat more efficiently and even change how your metabolism functions.

But like so many fad diets, is there any truth to the claims?

Kelly Faltersack, UW Health registered dietitian, explains that ketogenic diets are strict, high-fat, low-carbohydrate and moderate-protein diets. Following the diet puts the body in a state called nutritional ketosis, which forces the body to use fat for energy instead of carbohydrates. And it has proven effective in the treatment of epilepsy.

“Ketogenic diet therapy has been well researched for treatment of epilepsy," she said. "Studies have shown that about 50 percent of patients on a ketogenic diet experience a 50 percent or greater reduction in seizures. It is even the standard of care in treatment for GLUT1 deficiency – a rare genetic disorder that impairs glucose from reaching the brain."

Some may think the ketogenic diet sounds a lot like the Atkins diet, which was popular in the late 1990s. But the Atkins diet, while low in carbohydrates, puts greater emphasis on protein and not as much emphasis on fat. The result is that during the “induction phase” of the Atkins, a person might experience nutritional ketosis, but they would not remain in ketosis for the long-term, so the effects of the diet are not the same.

Faltersack said there are possible side effects from following a ketogenic diet – kidney stones, hypoglycemia, excess ketosis, acidosis, decreased bone mineral density and the “keto flu” – a collection of symptoms that includes nausea, constipation, headaches, fatigue and sugar cravings.

Because of the possible side effects, Faltersack said there are people who should not follow a ketogenic diet, including women who are pregnant, planning to become pregnant or breast feeding. Similarly, individuals with certain metabolic disorders that include a defect in fat metabolism, ketone metabolism or mitochondrial disorders, and individuals with pancreatitis or liver failure should not attempt the diet. It’s also important to recognize not every physician or dietitian has expertise in ketogenic diet therapy.

“Ketogenic diet therapy is a very specialized area of knowledge," Faltersack said. "I would encourage patients to work with a registered dietitian nutritionist who specializes in ketogenic diet therapy."

While she has seen a lot of positive effects for those who follow a ketogenic diet under medical supervision, Faltersack cautioned more research is needed.

“Ketogenic diets are an emerging area of research," she said. "Most studies have been short term, so the long-term sustainability or health implications are unknown. Because the long-term risks are unknown, it’s important to consider why a person would want to undertake the diet and whether it is sustainable.”

She points to promising new research for using ketogenic diets in type 2 diabetes and ongoing research for use with obesity, metabolic syndrome, autism, polycystic ovarian syndrome, migraines, brain tumors/cancer, traumatic brain injury, Alzheimer’s disease and more. What’s also not clear is whether there are benefits to being on the diet for the short term. Those who are following a ketogenic diet for epilepsy, for example, make a more permanent diet change.

If someone is interested in following a ketogenic diet, Faltersack strongly encourages talking with a physician first to make sure it is safe, and then working with physician supervision throughout the process. Baseline lab work and regular lab monitoring are recommended. Additionally, physical changes from following the diet may require medication doses to be adjusted due to weight loss, or as carbohydrate intake decreases and blood sugars change.

“There is a lot of potential in the use of ketogenic diets,” said Faltersack. “But people may still experience some health benefits from reducing the overall amount of carbohydrates they eat, especially sugar and refined carbohydrates. Talking with a physician can help figure out what’s best for you.”