Ketogenic Diet

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The ketogenic diet restricts carbohydrate intake, and to a lesser extent protein intake, to the point where the body converts that into ketones. These ketones are an alternative fuel source for most cells in the body, supplementing or replacing glucose as a critical fuel source. The ketogenic diet has the potential to help with a number of health conditions, but also has some significant potential health risks.

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1 What is the Ketogenic Diet?

The word "ketogenic" literally means that it creates Ketones. Our bodies produce ketones from fat when carbohydrates become scarce. To trigger ketosis (the production of ketones) we normally have to restrict carbohydrate intake to a very low level. The exact amount of carbohydrate varies by individual, but often it has to be restricted to less than 20g/day. (Normally the amount Fiber is ignored in the diet, and a figure of Net Carbohydrate is used.) Because the body will convert protein to glucose, it is also necessary to tightly control the intake of protein. Too much protein will prevent ketosis, but to a little will cause malnutrition. Some authors recommend the RDA for protein, while others suggest 0.6 to 1.0 grams per pound of lean body mass. When carbohydrate availability is restricted, the body does not immediately swap over to using fat and ketones, but rather there is a period of adaptation often referred to as Ketoadaptation. This made last a few weeks, and some people report feeling sluggish during this time. The ketogenic diet entails some potentially serious health risks, so medical supervision is required, along with regular tests and diet supplements. The ketogenic diet is one of the more stringent Low Carbohydrate Diets, and should not be taken lightly.

2 Are Carbohydrates Necessary?

There are various answers to this, both 'yes' and 'no'. While many cells can burn Ketones instead of Glucose, cells with few or no mitochondria must have glucose. However, protein can be converted to glucose, so while carbohydrate is necessary, it does not have to be consumed in the diet. If no protein is consumed, then the body will cannibalize muscle tissue to provide the required glucose. The only type of carbohydrate intake that could be considered critical for health would be Fiber, which is converted by the digestive bacteria into Short Chain Fatty Acids which are the primary fuel source for some cells such as the lining of the colon.

3 Advantages of the Ketogenic Diet

  • Ketogenic Diet as a Treatment. The greatest advantage of the ketogenic diet is probably its use for the treatment or management of disease.
    • Strong evidence: Epilepsy. There is a preponderance of evidence that the ketogenic diet is an effective treatment for epilepsy. I believe that anybody with epilepsy or is a caregiver for someone with epilepsy should discuss this with their doctor.
    • Limited evidence, but serious disease. Cancer, Alzheimer's disease, Parkinson's disease, Amyotropic Lateral Sclerosis (ALS), Schizophrenia, Depression, Bipolar disorder (therefore possibly Overtraining Syndrome), Type 1 diabetes. While the evidence is somewhat limited, there is a growing body of supporting literature, and these diseases have such a catastrophic impact on life that the ketogenic diet is almost certainly worth investigating. I would encourage anyone with one of these conditions to discuss the ketogenic diet with their doctor.
    • Evidence is unclear: Head trauma, stroke and hypoxia, heart disease, autism, inflammatory disease, severe hyperactivity. While of these conditions can be serious, the evidence for the use of the ketogenic diet is limited.
    • Little or no evidence: Migraine. While there was hope that the ketogenic diet would help with migraines, what little evidence we have suggests this may not be the case. However there is so little evidence, that this conclusion may change in future.
  • Hunger. Initial hunger can be greater due to reduced food volume. However, ketones suppress appetite so hunger tends to be less on a ketogenic diet.
  • Weight loss. The Ketogenic Diet can be effective in weight loss, possibly aided by the reduction in hunger.
  • Muscle Building. The ketogenic diet tends to have a protein sparing effect. There are anecdotal reports (myself included) that it is much easier to build muscle on the ketogenic diet.
    • Anecdotal suggestion that over-ketosis might cause growth inhibition in children.
    • The Ketogenic Mechanism of Action is probably the ketones levels, so increased protein intake (or Net Carbohydrate intake) can impair muscle growth.
  • Altitude. There is evidence that the ketogenic diet provides protection against hypoxia, and in this may convey a survival advantage at extreme altitude. In addition, it is possible that the ketogenic diet may improve the ability to function at high altitude. My personal experience is that during my Altitude Training, I am able to remain unimpaired while breathing much lower percentages of oxygen.
    • See "Survival of fasted rats exposed to altitude".

4 Disadvantages of the Ketogenic Diet

  • Health Risks. There are some serious Health Risks of the Ketogenic Diet. These can largely be mitigated with care, but anyone considering the Ketogenic Diet should be aware of both the risks and the mitigations.
  • Medical Supervision. The Ketogenic Diet should only be started under medical supervision. If you're smart, detail oriented and willing to take a few risks with your health then you can provide your own medical supervision.
  • Difficult to Get Right. The Ketogenic Diet is harder to get right than most diets, as even trivial amounts of carbohydrate will prevent ketosis. There is relatively little room for error, and mistakes can have an impact the lasts for longer than you would expect.
  • Easy to get wrong. It is remarkably easy to make a mistake and drop out of ketosis. Even if you measure and analyze all of your foods, the rounding that occurs on nutrition labels can result in you getting far more carbohydrate or protein than you expected. There is also the problem of mistakes on nutrition labels or the natural variation in nutritional content that occurs in foodstuffs. You also have to be careful with things you would not necessarily expect, such as toothpaste, or even skin lotions. There have been examples of people applying sunscreen (suntan lotion) and absorbing the carbohydrate through the skin. This causes them to drop out of ketosis and because they are on the ketogenic diet for epilepsy, they then have seizures.
  • Attention to detail required. I've found it necessary to measure and analyze all of my foods for some weeks before I learned what I could and could not eat.
  • Detective work. Many people experience problems achieving the expected level of ketones, and have to spend time analyzing all aspects of their diet. This detective work can be time-consuming and frustrating.
  • Supplementation required. The ketogenic diet is generally acknowledged as incomplete and requiring various levels of supplementation.
  • Monitoring required. To mitigate the health risks of the ketogenic diet, and to ensure adequate levels of ketones, it is necessary to perform regular testing while on the ketogenic diet. See Health Checks for the Ketogenic Diet for more details.
  • Lack of variety. It is much harder to get a variety of foods while on the ketogenic diet as so many foodstuffs are off-limits. This also leads to a lack of spontaneity, as foods have to be analyzed and there is little room for error.
  • Difficulty when traveling. The ketogenic diet is not trivial when you are at home, but it becomes even harder when traveling. In foreign countries it can be hard to know what is in different foods, and your ability to sample the local cuisine is greatly impaired.
  • Individuality. There appears to be a lot of individual variation in response to the ketogenic diet. This can make it hard to apply the generalized recommendations to your specific situation.
  • Adaptation time. It can take some weeks to adapt to the ketogenic diet, a process known as Ketoadaptation. During this time many people report feeling sluggish and the benefits may not be readily apparent. It is unclear how longer you can be out of ketosis without losing your Ketoadaptation, something that is important if you accidentally eat the wrong foods.
  • Many unknowns. While there is a significant body of research on the ketogenic diet and low carbohydrate diets, there are still a large number of unknowns. Our lack of knowledge makes it harder to provide good recommendations, but hopefully this will improve as time progresses.

5 Common pitfalls

This section should list out some of the more common pitfalls, or perhaps provide a checklist.

6 Required Reading

If you are seriously considering the ketogenic diet, you should read Dr. Kossoff's book as a bare minimum. The other books are worth reading, but I'm not as critical as Kossoff's volume.

Ketogenic Diets: Treatments for Epilepsy and Other Disorders, by Eric H. Kossoff is the best all-around book I've come across on the ketogenic diet. It focuses on the diet as a treatment for epilepsy, but touches on other conditions. It has a positive view of the ketogenic diet, but balances this with the caution that comes with being a medical practitioner that has used the diet for many years.
The Art and Science of Low Carbohydrate Living is an easy to read and entertaining look at the ketogenic diet. However, the book is biased in favor of the ketogenic diet, and it does not have a well balanced view that includes a comprehensive review of the risks.
The Ketogenic Diet: A Complete Guide for the Dieter and Practitioner is an interesting book, and while I believe it's worth reading, I find myself unconvinced by the evidence it presents. I think that this book is worth reading, but look to Kossoff's book as a better source of information.
The Art and Science of Low Carbohydrate Performance is obviously focused on the ketogenic diet for athletes. While it suffers from the same bias as the "The Art and Science of Low Carbohydrate Living", it is highly recommended for any athlete who is considering the ketogenic diet.

7 Recommendations

This section should provide recommendations based on each individual's probable situation.

8 References