November 16


Discover When You Should NOT Follow the Keto Diet

There are many documented health benefits including weight loss that can be found by following the ketogenic diet. However, not every diet is good for every person. In fact, because the keto diet temporarily converts the body’s metabolism to burning ketones instead of glucose, adverse reactions can occur. In addition, making sudden and dramatic changes in the foods you eat requires your body to make adjustments. These adjustments may make you feel uncomfortable for a while or they could even cause an adverse reaction. If you experience any of the adverse reactions listed below, please call a doctor immediately. 

The ketogenic diet is based on the philosophy that our ancestors ate fewer carbohydrates and more fats, especially during certain seasons. When carbohydrates are limited, the body resorts to burning ketones (fats) causing the body to be in a state of ketosis. However, our bodies are not designed to stay permanently in ketosis. That’s why the ketogenic lifestyle uses periods of cycling where more carbohydrates are consumed before going back into ketosis. Cycling in and out of ketosis is a healthy way to follow the keto lifestyle. If you’re interested in learning more about the health and weight loss benefits of a low carb diet, check out this FREE book offer.

Dr. Sarah Ballantyne writes a blog under website name of As a medical professional, she has done significant research into the benefits and possible risks of following the ketogenic diet. While it is easy to find lots of people saying the keto is great or keto is dangerous, Dr. Ballantyne has reviewed the research and presents a fair and balanced view. As an effort to provide a balanced view of the keto diet, please read what Dr. Ballantyne has to say about possible adverse reactions.

Adverse Reactions to Ketogenic Diets

As the list of health conditions that may be at least partially alleviated by ketogenic diets increase (and which currently includes epilepsy, Alzheimer’s, Parkinson’s, Autism, traumatic brain injury, bipolar disease, PCOS, cancer, obesity, and diabetes), so too does a body of literature pointing to common side effects and potential adverse reactions.

Adverse reactions to a ketogenic diet have been reported in the scientific literature. Yes, even including well-designed clinical trials performed and published very recently.  In fact, the intolerability of side effects and adverse reactions is the primary reason for trial participants to drop out of clinical trials (other reasons for trial drop-outs include ineffectiveness of the diet, and that the diet is too hard to follow).

Adverse reactions are not the same thing as side effects.  An adverse reaction is an, unwanted/unexpected and dangerous reaction to a therapeutic agent.  In contrast, a side effect is a secondary, typically undesirable effect of a therapeutic agent.  More simplistically, side effects are minor and adverse reactions are not. Side effects are typically what are reported in shorter-term studies, where as both side effects and adverse reactions are reported in the long-term ketogenic dietstudies (typically 6 months to 2 years, but any study that allows for keto-adaptation, which takes up to a month, can be considered long-term).  This article is not a discussion regarding side effects, the list of which has some overlap with the list of adverse reactions (for example common side effects include minor gastrointestinal symptoms).  This article is to draw attention to the documented adverse reactions, which include:

  • Gastrointestinal disturbances (diarrhea, vomiting, nausea, constipation, GER)
  • Inflammation risk
  • Thinning hair/hair loss
  • Kidney stones
  • Muscle cramps or weakness
  • Hypoglycemia
  • Low platelet count
  • Impaired concentration/cognition
  • Impaired mood
  • Renal tubular acidosis
  • Nutrient deficiency
  • Disordered mineral metabolism
  • Poor growth in children
  • Skeletal fracture
  • Osteopenia/osteoporosis
  • Increased bruising
  • Sepsis, infection, bacteria overgrowth
  • Pneumonia
  • Acute pancreatitis
  • Long QT intervals
  • Cardiomyopathy
  • Shift towards atherogenic lipid profiles (including hypercholesterolemia and hypertriglyceridemia)
  • Heart arrhythmia
  • Myocardial infarction,
  • Menstrual irregularities and amenorrhea
  • Death

That’s a long list. A long list of not-good things. And did you catch that last one? Five scientific papers have reported deaths as an adverse effect from long-term ketogenic diets (here’s the citations: Stewart, et al., 2001Kang, et al., 2004Kang, et al., 2005Bank, et al., 2008Suo, et al., 2013 and make sure to check out the free PDF download of my Literature Review at the bottom of this post which contains details on all of the papers reporting adverse reactions). Two of these papers are case studies, and the other three are papers derived from two separate clinical trials, all studies in epileptic children. Some of the deaths can be attributed to extra complications from secondary conditions or accidents that befell the child during the course of the clinical trial; however, other deaths—most typically from severe infection or heart disease—are attributed directly to long-term ketosis.

The Relevance of Adverse Reactions

I believe the potential for adverse reactions is important information for people to know when they are weighing a ketogenic diet versus other diets or therapeutic options. But, that doesn’t mean that everyone need avoid ketogenic diets. It’s a question of weighing the pros and cons for each individual.  And certainly some of the above adverse reactions can be prevented with careful choice of foods and/or targeted supplementation (such as nutrient deficiency).  And it’s important to emphasize that the above list of adverse events also points to a long list of tests that can be performed regularly by a supervising health professional to monitor for any potential detriment in the event that there are compelling reasons to undertake a ketogenic diet.

Dr. Ballantyne’s Scientific Literature Review



The ketogenic diet has many benefits and works well for most people, BUT it is definitely not for everyone. It is important to make an informed decision. Before starting any diet, consult with a doctor to make sure they approve of your plan based upon your current health condition. Also, if you experience any of the above adverse effects, call your doctor immediately.

The ketogenic diet is based upon the philosophy that our ancestors ate fewer carbohydrates and more fats, especially during certain seasons.  However, our bodies are not designed to stay permanently in ketosis. That’s why the ketogenic lifestyle uses periods of cycling where more carbohydrates are consumed before going back into ketosis.

At the time of writing this post, we are giving away free copies of the Body Reboot book to help people lose weight and get healthy! Just cover the small cost of shipping, and we’ll send a FREE copy to your door. Go over to this page to see if copies are still available!

Bruce Fleck, PhD

About the Bruce Fleck, PhD

I help professionals overcome a health, career, or relationship crisis and make it a turning point for building a better life.

{"email":"Email address invalid","url":"Website address invalid","required":"Required field missing"}

Take The Crisis Cure™ Quiz

Find out how well you're coping with your health, career, or relationship crisis.

Learn More About The Crisis Cure™

Based on experience and backed by science, The Crisis Cure™ Course and Coaching Program can not only help you overcome your crisis but also make it a turning point for building a better life.