It seems like everyone has heard of the ketogenic diet (aka “keto”). A polarizing topic, some people swear by it, and some see it as just another fad. During my recent dietetic internship, I met a woman who was morbidly obese wondering if she should try keto to lose weight. Her history included an abdominal surgery, after which her gut had never been the same. She had digestive issues that sometimes put her in the position of having to sprint to the restroom - not an easy feat for an individual of her size. My “gut” reaction was that the keto diet wouldn’t be right for her: high fat and low fiber are not the usual recommendation for GI issues. But as a student and an intern, I wanted to learn more before making a recommendation.
If you don’t know about the keto diet, I don’t know where you’ve been – certainly not on YouTube watching weight loss videos. The ketogenic diet is a pattern of eating that is high in fat, moderate in protein (NOTE: the keto diet is NOT a high protein diet as many believe), and low in carbohydrates compared to the traditional dietary recommendations. It was initially prescribed as a diet for patients with epilepsy and intractable seizures. There is a significant body of research demonstrating the diet’s effectiveness for this population. The way keto works is that the body, deprived of glucose, starts to use fats or lipids for energy. Ketone bodies are a product of this pathway and can travel through the bloodstream and be utilized for energy by all the body’s cells and organs. Even the brain can adapt to using ketones rather than glucose as an energy source. It is this adjustment in metabolism that appears to be behind its effectiveness in preventing seizures.
Due to its noted ability to alter brain metabolism, the ketogenic diet is being investigated as a possible therapy for autism, Alzheimer’s disease and other degenerative brain conditions, even migraines. But the possibilities do not end there! Could the keto diet be useful for diabetics who are not able to effectively handle large quantities of glucose in the bloodstream? How about in cancer – cancer cells thrive on glucose, but may not be able to use ketones for energy. And yes, the keto diet has been shown to promote weight loss in some individuals. But here’s the deal: there has been little research done on the ketogenic diet. We don’t know for sure that it doesn’t work, but we can’t yet verify that it does either.
I spent a day with two dietitians who work with kids with epilepsy and their families utilizing the keto diet to minimize their symptoms. It really does work – not in all patients, and it doesn’t cure the disease, but it can dramatically improve overall quality of life by reducing seizure frequency, sometimes halting seizure activity altogether. The clinical version of this diet is pretty extreme and doesn’t look anything like what a regular person might eat. Between 75 and 90% of calories come from fat, which means lots of heavy whipping cream, butter, and oils. Total protein and carbohydrates combined make up, at the most, 25% of total daily intake. (again, the ketogenic diet is not a high protein diet) It is important that these ratios are maintained for the body to stay in ketosis. Ketosis is a state in which fat is being used for fuel and ketones are being produced. It can be checked by measuring for ketones either in the blood or in the urine. These kids are monitored very closely, not only for the presence of ketones, but for some of the potential side effects of the diet.
Keto side effects:
CONSTIPATION. Unsurprisingly, it is the most common side effect considering fiber, which can keep us regular, is found in carbohydrate foods. Given the choice between seizures and constipation, putting up with this side effect is probably preferable, especially since it can be managed with medications like Miralax. If you’re just trying keto for kicks, constipation may be a deal-breaker.
ACIDOSIS. Ketones are acidic and a person in ketosis does have slightly more acidic blood. If the pH drops too low, it can become a problem, especially for the kidneys. With monitoring, acidosis can generally be prevented and treated. OF NOTE: ketosis is different from diabetic ketoacidosis – an acute condition that occurs in diabetics when their body is unable to take up glucose in the blood due to insufficient insulin creating an emergency situation. ALSO OF NOTE: a high protein diet can be hard on the kidneys because proteins create nitrogenous wastes the kidneys have to excrete. Since the keto diet is not a high protein diet, it is not necessarily bad for the kidneys, unless acidosis occurs.
NON-COMPLIANCE. Not really a side-effect so much as a downside of taking on a diet that is super hard to do. Kids in the keto clinic have their menus created, calibrated, and regularly adjusted by registered dietitians who specialize in this work. Parents of children with epilepsy are generally very motivated to stick with it for the welfare of their child. Lay people who just want to try keto likely won’t have these advantages or access to an RD. They are not monitored to ensure they are in ketosis but not acidosis. Non-compliance is actually one of the biggest reasons there isn’t a ton of useful scientific data available regarding its effectiveness for other conditions – study subjects find it extremely challenging to get it right.
HIGH CHOLESTEROL? I assumed that a high fat diet, particularly one that includes quantities of saturated fat (butter, cream, eggs, cheese, etc) would lead to high cholesterol, which is a risk factor for cardiovascular disease. As it turns out, blood lipid levels rise initially in people beginning a ketogenic diet, but studies have demonstrated that they normalize after a few months. Which means that going on this diet to solve one problem (epilepsy) does not mean another one (heart disease) will be created down the road. Unexpectedly, not a side effect after all – if the diet is done right.
I asked the dietitians I joined for their opinion on the lady I had met as an intern. One of them claimed that, in her experience, she had not found the diet to be contraindicated for anyone. She maintained that in such a case, helping a patient to lose weight rapidly might supersede other conditions. I was surprised. I think of keto as being quite controversial, even frowned upon, particularly in the nutrition community, but as mentioned, some people are hard core believers, and many have good reason to be.
A study published in 2018 by Mohorko et al demonstrates keto’s effectiveness in promoting weight loss, along with several other positive findings, and it is not alone in suggesting this diet may help combat obesity. But there are lots of weight loss diets out there. Is keto somehow better, or is it just another version of the same old concept – eat fewer calories and burn more? And fat is higher in calories per gram than carbs or protein, so how is anyone able to get away with eating mostly fat?
Why it works – the theories:
FEWER CALORIES CONSUMED. Restricting carbohydrates and limiting protein means most people run out of options and end up eating less.
FAT IS SATIATING. People on the diet eat less because they get full more quickly.
KETOSIS IS AN ENTIRELY DIFFERENT TYPE OF METABOLISM. It could be that being in ketosis and using fat for fuel somehow burns more calories than our usual glucose based metabolism. Or maybe ketosis, which depresses insulin levels, affects other hunger hormones and reduces appetite. Or maybe…you name it - speculation here is what has really caught people's interest. Unfortunately, not enough research has been done to definitively establish why ketosis causes certain effects.
So what’s the take away? Well, everyone would love keto to magically solve the obesity epidemic, put an end to metabolic syndrome, knock out Alzheimer’s, and cure cancer for good measure. And who knows, someday we may all regret that we ever recommended brown rice over eating butter with a spoon. But at this point, high quality evidence of keto’s therapeutic effects beyond seizure control is still pending, and studies on the long-term effects of the diet are sorely lacking.
Individuals trying the diet on their own should be warned about the challenges they might face. Ketosis takes time to establish and adjust to, but can be instantly derailed by consumption of too much carbohydrate, or even protein, which our body is capable of breaking down to glucose. You can't cheat on this diet without undermining it completely! Are people on keto actually measuring their ketone levels? If not, they don’t know if they’re in ketosis or not, and if they’re not, they’re basically just eating a high fat diet, which has serious health risks. A balanced diet full of vegetables and fruits, low-fat proteins, whole grains, and a moderate amount of fat is still the general recommendation for most folks. Boring, I know. I wonder if keto hasn’t taken off simply because it is new and different. People get excited by the idea that fat is back after having been shunned from plates a couple decades ago.
So what would I say to the woman from the top of this story if I could meet her again now? I think I would talk to her in depth about the pros and cons of the keto diet. Let her decide, and then provide as much assistance as possible with whatever decision she made. If keto was her call, I would help her do it right, monitor levels, and keep track of progress. But I would not oversell it. It is uncharted territory, and though it may be exciting to go to the extreme and embark upon a journey into the unknown, when it comes to health, maybe playing it safe and boring isn’t such a bad idea.
My name is Lorelei Sturm. Some of you may know me as a yoga instructor with Chicago’s Neighborhood Fitness Centers. I am also a Registered Dietitian with a Master’s degree in Nutrition. CNF is committed to helping its members lead healthier lives by encouraging wellness and a healthy lifestyle in addition to fitness. So, what burning nutrition questions do you have? Let me know in the comments below.
Barry D, Ellul S, Watters L, Lee D, Haluska R Jr, White R. The ketogenic diet in disease and development. Int J Dev Neurosci. 2018 Aug;68:53-58.
Gershuni VM, Yan SL, Medici V. Nutritional Ketosis for Weight Management and Reversal of Metabolic Syndrome. Curr Nutr Rep. 2018;7(3):97–106.
Kraeuter AK, Guest PC, Sarnyai Z. The Therapeutic Potential of Ketogenic Diet Throughout Life: Focus on Metabolic, Neurodevelopmental and Neurodegenerative Disorders. Adv Exp Med Biol. 2019;1178:77-101.
Mohorko N, Černelič-Bizjak M, Poklar-Vatovec T, Grom G, Kenig S, Petelin A, Jenko-Pražnikar Z. Weight loss, improved physical performance, cognitive function, eating behavior, and metabolic profile in a 12-week ketogenic diet in obese adults. Nutr Res. 2019 Feb;62:64-77.