The Ketogenic Diet- Do-able or Dangerous?

What is it all about anyway?

The Ketogenic or “Keto” Diet has been getting a lot of buzz recently. Essentially, the method includes a low-carb, moderate protein, high fat diet.  Many people are using this fad diet for quick fix weight loss. However, I and other eating disorder savvy nutritionists are against the approach. While the science behind “Keto” has been clinically indicated in some very special circumstances, this diet is not sustainable for the general public nor safe for those recovery from eating disorders. 

The Keto diet is based on a body process known as ketogenesis. Our body’s main source of energy is glucose. When glucose is unavailable our body uses fat as a backup energy source which when broken down produces ketones. When you follow a low- carb, moderate protein, high fat diet your body enters a metabolic state of ketosis. While this may seem innocuous, The Keto diet, ketone production and/or ketosis is not without its negative consequences. Below are some of the down-side dangers to following this diet plan. Let's take a closer look.

The Down-Side:

  1. “Keto Flu:” Individuals who embark on the Keto diet report feeling sick after a few days of eating the suggested diet.They notice overall energy levels go down, feel lethargic and a host of GI issues. 

  2. Keto breath: When carbohydrates are restricted and our body uses fat for energy, fatty acids produce ketones. Ketones can produce “keto breath.” People describe this specific  taste and odor as being metallic or fruity smelling. It can even have a strong odor similar to nail polish remover.

  3. Nutrient Deficiencies: Because whole food groups are excluded, nutrients found in carbohydrate rich foods such as whole grains and fruit are decreased in the diet.This can lead to nutrient deficiencies. Removing grains and fruits lowers overall fiber intake which negativity impact gut health. 

  4. Gastro-Intestinal issues: Speaking of the gut, when diets are overloaded with protein and fat the gallbladder has to work harder and the system becomes overwhelmed. Main consequences include gastro-intestinal upset, stomach distress and diarrhea. In addition, the lack of fiber of this diet can cause constipation. Moving back and forth from constipation to loose stool can even exacerbate IBS (Irritable Bowel Syndrome). In addition, because individuals on Keto avoid sugar they tend to eat foods with artificial sweeteners and sugar alcohols. Sugar alcohols and artificial sweeteners also impact gut health and add to gut chaos.  

  5. Decrease Performance: While some athletes believe this diet can enhance sports performance current research shows quite the opposite. A recent studyin the Journal of Sports Medicine and Physical Fitness, found that participants performed worse on high-intensity cycling and running tasks after four days on a ketogenic diet in comparison to those who ate a higher carbohydrate diet for four days. Weiss who conducted the study suggests that when the body is in an acidic state (as a result of ketosis) it cannot perform at peak levels. 

  6. Ketoacidosis: This diet has been used in conjunction with treatments for Diabetes. While there is some studies that show better insulin control in Type 2 diabetics there are also potential dangers for those with Type 1.Putting your body into ketosis can significantly influence glucose levels. It can bring on a dangerous condition called ketoacidosis. When this happens blood becomes too acidic which in turn damage the liver, kidney and brain. It can even be fatal.  Although rare, there have been cases of ketoacidosis in non diabetics who have tried this type of diet.

  7. Weight Gain: As with most other fad diets, research shows that weight loss is only temporary. In fact, because this low carbohydrate diet is not sustainable as soon as individuals go off this diet and resume normal eating they gain weight. Many crave, overeat and binge on foods that contain sugar and carbohydrates. Chronic dieting is also a real possibility which can lead to disordered eating and eating disorders.

  8. Decreased Lean Muscle Mass and Decreased Metabolism: Another consequence of Keto related body issues includes both loss of lean muscle mass and decreased metabolism. Weight loss due to restriction almost always results in a loss of muscle tissue. As you lose muscle your metabolism decreases. When you gain weight you’ll most likely gain fat. In other words, it’s a triple whammy! Although you may lose weight initially, the consequences of muscle loss, decreased metabolism and potential of a higher fat percentage can dramatically affect your resting metabolic rate and set point. 

  9. Increased Risk of Heart Disease and Other Medical Illnesses. A diet low in complex carbohydrates and high in fat and protein may mean lasting detrimental health effects. Many foods in these categories are also high in saturated fat and cholesterol. A study, published in the Lancet, found that people who followed diets that were low in carbs and high in animal proteins had a higher risk of early death compared to those who consumed carbohydrates in moderation. 

The Up-Side:

Reduction in Seizures in Epilepsy: Although, medical professionals are unsure why, The keto diet has drastically reduced seizures in epileptic children.[2]While I was a dietetic student at NYU, I volunteered weekly at NYU’s epilepsy center. I saw firsthand how the keto diet reduced and in some cases eliminated epileptic seizures. While I was able some remarkable results, I also saw how difficult and alienating it was for children to follow this restricted diet. Parents would have to prepare and pack most foods at home for any social gathering and they were deprived of eating foods they enjoy.

The bottom line:

The ketogenic has some promising results in the treatment of epilepsy in children and more research is being conducted on how this method may be beneficial for other neurological disorders and disease states. This said, it is not a healthy way to eat for those pursuing general wellness and especially those in recovery from eating disorders. It is important to be aware of the negative consequences to following such an extreme diet.  Always work with an RD professional if you have concerns about your diet. While following a fad diet might seem like a great idea, it can cause more harm than good.   


Hemingway C, Freeman JM, Pillas DJ, Pyzik PL. Pediatrics.2001 Oct;108(4):898-905. The ketogenic diet: a 3- to 6-year follow-up of 150 children enrolled prospectively.

Klement RJ  Oncologist.2013;18(9):1056. doi: 10.1634/theoncologist.2013-0032.Calorie or carbohydrate restriction? The ketogenic diet as another option for supportive cancer treatment.  

Gupta L, Khandelwal D, Kalra S, Gupta P, Dutta D, Aggarwal S. Ketogenic diet in endocrine disorders: Current perspectives. J Postgrad Med. 2017 Oct;63(4):242.

Teicholz, N. (2018). Dietary carbohydrate intake and mortality: Reflections and reactions. The Lancet Public Health,3(11). doi:10.1016/s2468-2667(18)30206-8

von Geijer L, Ekelund M. Ketoacidosis associated with low-carbohydrate diet in a non-diabetic lactating woman: a case report. J Med Case Rep. 2015 Dec;9(1):224

Wroble, K. A., Trott, M. N., Schweitzer, G. G., Rahman, R. S., Kelly, P. V., & Weiss, E. P. (2019). Low-carbohydrate, ketogenic diet impairs anaerobic exercise performance in exercise-trained women and men: A randomized-sequence crossover trial. The Journal of Sports Medicine and Physical Fitness,59(4). doi:10.23736/s0022-4707.18.08318-4.

Zawn Villines. Reviewed by Debra Sullivan, PhD, MSN, RN, CNE, COI

Differences between ketosis and ketoacidosis. Last reviewed     Mon 21 January 2019.