Dr. Novella’s Response:


Thanks for your note. I know I left a lot of specifics out of the article – they only give me 800 words.  So here is some clarification:

The term “fad” is used to refer to a diet with broad recommendations for everyone – not necessarily a new or short-lived diet. I know Atkins has been around for decades, but its surging popularity is recent and probably will not last long, although the Atkins diet, I’m sure, will be around for awhile.

I have carefully reviewed the literature on Atkins and other diets. They show that there is a short term advantage for hunger, but they also show the following:
– weight loss during the studies was modest
– the advantage to hunger for low carbs was temporary, apparently not lasting more than 6 months
– weight loss correlates with calorie intake. There has yet to be a single study which shows that you can lose more weight at the same calories by just lowering carbs.  So, you were reducing your calories even though you didn’t realize it.
– most people on Atkins gain the weight back after a year or so. The 5-year success rate is very low, and it is better on low-fat diets. However, the best measure of long-term success is just reducing calories and exercising regularly.

Ketosis is definitely part of an ultra-low carb diet, but it is not a healthy condition to maintain. It hurts the brain, and in extreme cases can even cause coma (diebetics can go into a ketoacidodic coma if untreated). Ketosis is not a safe and effective long term strategy for maintaining weight loss – and long term is all that counts. At best, it is a short-term gimmick, but it often motivates people to buy into the low-carb diet.

You should note that the dept. of agriculture just came out with their updated guidelines, based upon a lengthy review of all available evidence by a panel of experts – and they recommend to count calories, not carbs, and to exercise regularly.

I know I lumped all diets together – I had to due to length constraints, but I did focus on what they have in common.  I don’t think there is anything dangerous about recommending reducing calories and exercising as a way to maintain weight and good health; to focus on the long term, and not put your faith in easy weight-loss schemes that the evidence shows have no long-term advantage.

I hope this clarifies my position. Thanks again for your letter.

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