“A ketogenic diet alters the metabolic pathway of how your body burns fuel for energy,” says Audrey Fleck, RDN, an integrative and functional nutritionist in Bucks County, Pennsylvania. Rather than using glucose — which is the preferred method of energy for cells — severely restricting carbs and eating a high-fat diet sends your body into ketosis, a state where it’s burning fat instead of carbs for energy. Asking the brain and body to run on this alternate fuel may impact insulin regulation and inflammation and may help manage some health conditions. But remember that there are several ways you can do a ketogenic diet. Butter and bacon will get you into ketosis, but that doesn’t mean they’re the best choices. Also, because a typical keto diet food list is so restrictive, you need to speak with your doctor before trying it. If you get the green light, keto beginners can benefit from working with a registered dietitian knowledgeable in keto diets who can help you plan a diet, maximizing your nutrient intake while avoiding potential deficiencies. Here are conditions that the keto diet can or may be recommended for — and when it’s definitely not. According to the Epilepsy Foundation, it can help control seizures in children, especially those who don’t respond to medication alone. Half of kids with epilepsy who are on the keto diet cut the number of seizures they suffer by at least 50 percent. (1) Based on preliminary research suggesting keto may be helpful for people with type 2 diabetes, some hospitals, such as the Cleveland Clinic, have comprehensive programs dedicated to using the nutritional approach to help treat diabetes. Furthermore, companies like Virta are studying how nutritional ketosis may play a role in prediabetes and type 2 diabetes treatment. That said, definitive scientific evidence is lacking. A meta analysis from 2021 did a systematic review of 14 relevant studies over the past decade and determined there was no consistent evidence that keto diets positively influenced key diabetic measures like blood sugar levels. (2) What is known is if you’re on medication for diabetes or insulin, you’ll want to work closely with a prescribing doctor who may need to adjust your medication dosage as you restrict carbohydrates, Moree says.
Metabolic Syndrome
Metabolic syndrome is a cluster of risk factors: abdominal obesity; high triglycerides, blood pressure, and blood sugar; and low HDL, or ”good” cholesterol. (3) One factor that plays into metabolic syndrome is insulin resistance, so getting that under control may also reduce your risk for developing this condition, says Moree. One small study on 30 adults found that adults with metabolic disease who followed a keto diet for 10 weeks lost more weight and body fat, and lowered their A1C levels compared with those who followed a standard American diet, which is rich in added sugar, refined carbs, and unhealthy saturated fat, with or without exercise. (4) One thing to keep in mind is that this was a small study and done only in the short term. And there’s no telling whether the participants’ health and weight improvements would have been better on a conventional healthy diet compared with the keto diet. A 2018 study that looked at a wider range of relevant studies found compelling evidence that a keto diet might help manage metabolic syndrome, although it also suggested that more research was needed.
Obesity
Insulin resistance is a large component of the metabolic dysfunction in obesity, says Fleck. “Obesity puts you at a higher risk of developing blood sugar issues or type 2 diabetes,” she says. A small study looked at 45 obese participants either on a very low-calorie ketogenic diet or a standard low-calorie diet. (5) After two years, keto dieters lost about 27 pounds on average compared with less than 10 pounds in the low cal group. The keto dieters also shed more visceral, or belly, fat. A keto diet may also help preserve lean body mass during weight loss, helping to prevent a metabolic slowdown that can often cause people to regain weight, according to research from 2018. (6) That said, a more recent review of studies published in the journal Cureus concluded that while the keto diet can offer short-term weight loss success — including ”transient decreases in blood pressure, triglycerides, and glycosylated hemoglobin” — the changes were not statistically significant after 12 months. The review authors believe further research is needed to look at the long-term efficacy and risks of the keto diet and suggest it may lead to increased cardiovascular risks.
Certain Cancers
Using the ketogenic diet as one aspect of cancer treatment is certainly gaining traction. “We now know that epileptic syndromes are due to the same [genetic] mutations in PIK3CA as are seen in [some] cancers,” says Lewis Cantley, MD, PhD, professor of cell biology at the Dana-Farber Cancer Center Institute at Harvard Medical School. Ketosis may also improve the effectiveness of chemotherapy and radiation, suggested one review. (8) While this is potentially exciting, the review also notes that keto diets can be high in saturated fat and low in fiber and may eliminate foods known to be protective against cancer (such as fruits and legumes). Dr. Cantley says that more well-designed, well-controlled clinical trials are needed to show what role, if any, the keto diet may play in cancer treatment. Talk to your oncologist before any major change to your diet. “Unfortunately, different oncologists will provide different advice. I know that some physicians recommend low-carbohydrate diets to their cancer patients, but they are in the minority. Until the FDA [U.S. Food and Drug Administration] weighs in on this based on well-designed clinical trials, there will be widely differing views by physicians,” Cantley says.
Epilepsy in Adults
The Epilepsy Foundation notes that a ketogenic diet is usually not recommended for adult patients because it’s so restrictive. (1) Instead, they recommend the modified Atkins diet, which is an Atkins diet that severely restricts carbohydrates and encourages fat intake, but (unlike keto) doesn’t restrict protein. (9)
Migraines
There’s a growing knowledge about the role inflammation plays in migraine headaches, and for that reason, a keto diet may be useful in reducing headache days, says Moree. (10) But it’s not the only diet that can help lessen episodes, notes the American Migraine Foundation. (11) If you’re looking to use a keto diet to control headaches, talk to your doctor first.
Polycystic Ovary Syndrome (PCOS)
PCOS is known as a fertility disorder in women, but it’s now recognized as a metabolic condition, too. Women who have PCOS have an increased risk for insulin resistance, diabetes, and obesity. (12) Moree says inflammation is another factor in exacerbating symptoms. “The two main things that keto can help with — inflammation and insulin resistance — play a big role in PCOS. I commonly use the keto diet as a first line of defense in patients with PCOS,” says Moree. One small study found that the keto diet may be positive for women with PCOS. Still, more long-term, randomized controlled trials showing keto is safe and effective for every woman with PCOS are needed, which means the eating approach is not widely recommended as a first-line treatment for the condition.
Autism
A very small 2018 study of 15 children found that a “modified” gluten-free keto diet with supplemental MCT (medium-chain triglyceride) oil may help improve some behavioral symptoms associated with autism spectrum disorder after three months. (13) While this research is limited in size and scope, one more recent review of seven studies also found that a keto diet can improve certain behaviors in autism. Still, more studies are needed to generalize the keto diet as a proven treatment for autism.
Dementia and Alzheimer’s Disease
While it’s not an officially recognized medical term, some people are referring to Alzheimer’s disease as ”type 3 diabetes” because both conditions are associated with insulin resistance. Nonetheless, experts say that more research is needed, and that it’s a sweeping generalization to say that a keto diet is appropriate for everyone at risk of Alzheimer’s. Some, like Richard Isaacson, MD, adjunct associate professor of neurology at Weill Cornell Medicine in New York City, are supportive of low-carb diets. “I believe when people are fueling their brain using ketones or calorie or carbohydrate restriction, it’s a cleaner burning fuel, and a better way to delay brain aging,” he says. Still, the evidence isn’t there to say that the keto version of the low-carb diet is always necessary, or even helpful. Indeed, it may benefit some. For example, a small 2012 study that followed 23 older adults at a higher risk for Alzheimer’s found that they experienced better memory function after six weeks on a keto diet. (14) A more recent review of 12 studies found improved brain metabolism and cognitive benefits from the keto diet in relation to Alzheimer’s. For others with certain genetics, though, it may be harmful, says Dr. Isaacson. For that reason, there’s no one-size-fits-all recommendation. Anyone going on keto needs to have his or her labs taken throughout the process, and do it in conjunction with their treating physician and a registered dietitian, he says.
Parkinson’s Disease
Up to 80 percent of people with Parkinson’s may also go on to develop dementia. (15) The ketogenic diet may help preserve cognitive function and memory in people who are at a relatively higher risk for dementia. “For individual patients who have [an] elevated risk for neurodegeneration, such as Alzheimer’s disease, I’m not shy about suggesting it as an intervention — and, typically, I do,” says Robert Krikorian, PhD, professor emeritus of clinical psychiatry at the University of Cincinnati College of Medicine. That said, the keto diet as a therapy “is not widely accepted, but in my mind, there’s enough data to recommend it,” he says. According to a study that Dr. Krikorian led, published in 2019, ketosis appears to have multiple effects, including improved brain function and cognition, potentially by way of enhancing energy production and normalizing insulin levels in the brain. One reason that low-carb diets like keto may improve cognitive functioning is through reducing insulin secretion in the body. That’s important because research suggests that higher insulin in the circulation correlates with lower levels of insulin in the brain, says Krikorian. Insulin in the brain is necessary to support memory consolidation; it also correlates with an enzyme that helps clear beta amyloid out of the brain, proteins that form plaques that disrupt brain function as in Alzheimer’s disease, he explains. That said, while it’s a promising area of research, more long-term studies still need to be done before the keto diet is widely recommended in this disease.
Eating Disorders
If you have a history of an eating disorder like anorexia or bulimia, or disordered eating, you should not be following a restrictive diet; doing so can cause a relapse. Instead, seek out a registered dietitian who specializes in eating disorders, who will have the tools to help you address these complex diseases.
Binge-Eating Disorder (BED)
BED is also an eating disorder, but it warrants being called out specifically here. Anecdotally, some people have said they’ve “treated” their BED with keto because the high-fat plan keeps them full, preventing binge episodes. But “Binge eating disorder is a severe and problematic eating disorder which cannot be treated with a restrictive diet. A person may temporarily feel that they are better, or feel more in control, but sooner or later they will experience compensatory eating, binges, and cravings,” says Sumner Brooks, MPH, RDN, CEDRD, a certified eating disorder registered dietitian in Portland, Oregon, and founder of the organization EDRDPro, which stands for Eating Disorder Registered Dieticians and Professionals. “I have worked with many clients who come to me after losing weight while on keto, suffering with out-of-control feelings around carbohydrates, and blame themselves, when really it is the diet that is the problem,” she says. Brooks notes that the lack of hunger on the plan is also an issue, as hunger is a normal human body cue that one shouldn’t work to suppress. Proper treatment of BED is “regular, adequate, satisfying” food intake and possibly psychological therapy in order to learn coping skills for stress and emotions that trigger BED episodes, she says — not keto.
Gallbladder Removal
If you’ve had your gallbladder removed, your body no longer has a reservoir for bile, a fluid that aids digestion, particularly fat. “If you go keto without boosting bile flow [which your body can’t do without a gallbladder], you’ll feel awful,” says Hammond. If you’re absolutely set on trying keto, talk to a professional before jumping into the diet, she says.
Multiple Sclerosis (MS)
Because the keto diet is sometimes used for neurodegenerative diseases, it’s been said that it can be used to treat MS. But research on a keto diet for people with MS is severely lacking. One review from 2015 noted that in test tube and animal studies the keto diet may improve the function of mitochondria (the powerhouse of cells) and increase ATP production (cellular energy), thereby theoretically preserving brain function and slowing the progression of MS. (16) And in a study from 2022 that looked at 65 patients with relapsing MS, researchers noted improvements in body composition, fatigue, and depression. Still, the National Multiple Sclerosis Society notes that there are still questions about the long-term safety of such diets, and they can exacerbate fatigue and constipation, both common side effects of MS. (17)
