February 5, 2016

Not All Low Carb Diets are Ketogenic – Part 1

When reading or hearing about low-carb diets, you may have heard the term 'ketogenic diet'. Increasingly, people have questions about this. Are all low-carb diets ketogenic? Is that a good thing or a bad thing? What constitutes a ketogenic diet? What are the advantages and disadvantages of a ketogenic diet? And, there are more questions.

The biggest factor in whether or not a diet is ketogenic is how low in carbohydrates it is. It also depends on how many carbohydrates are consumed on a day-to-day basis. Some people can be ketogenic for several days and then consume a few too many carbohydrates and need to start over to get back into a ketogenic state.

A moderate reduction in carbohydrate can be very helpful to many people, but it won't be ketogenic. Basically, there are three approaches to low-carb eating, only one of which focuses on ketosis as a goal throughout the diet. Diets such as the Atkins Diet start out as a very low-carb ketogenic diet, but as people add carbohydrate, many or most will be eating too many carbohydrates to be in ketosis.

It is probably more accurate to talk about "the degree to which a diet is ketogenic" rather than "whether or not a diet is ketogenic". I will cover ketosis in a future blog so I will not cover it here.

A source of confusion is that there is a transition period while the body is adapting to using fats and ketones instead of glucose as its main fuel. There can be negative symptoms during this period (fatigue, weakness, light-headedness, headaches, mild irritability), but they usually can be eased fairly easily. Most are over by the first week of a ketogenic diet, though some may extend to two weeks. Athletes who closely track their performance may notice more subtle effects up to 6-8 weeks from the start of the diet, and there is some evidence that it may take even longer, up to 12 weeks, for 100% adaptation.

Ketogenic diets are becoming more popular, and for a variety of reasons. In addition to weight loss, they are beginning to be studied as a treatment or prevention for other conditions. They are already well established as a treatment for epilepsy, and researchers are interested in uses for other neurological conditions. A June 2013 paper in the European Journal of Clinical Nutrition listed the following conditions as possibly being helped by ketogenic diets:
Strong Evidence
  • Epilepsy
  • Overweight and Obesity (weight reduction)
  • Type 2 Diabetes
  • Cardiovascular Risk Factors (particularly improving triglycerides, HDL cholesterol, and patterns of LDL cholesterol most associated with arterial plaque)

Emerging Evidence (some evidence with more research in progress)
  • Neurological Diseases other than epilepsy, including Parkinson's Disease, Alzheimer's Disease, narcolepsy, brain trauma, and amyotrophic lateral sclerosis
  • Polycystic Ovarian Syndrome
  • Acne
  • Some types of cancer (especially, perhaps, some types of brain cancer)

In addition, some athletes are experimenting with using a ketogenic diet to enhance endurance.

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