Last week, the Journal of the American Medical Association (JAMA) was rather aggressively promoting an opinion article about the ketogenic diet. I know I’m getting into some rather controversial waters here, but I feel it is important to point out some concerns that I have about this article.
A ketogenic diet is an eating plan that restricts carbohydrates to a maximum of 20-50g per day (which is very low), which causes the body to burn fat as fuel instead. The liver converts fatty acids to ketone bodies, which serve as an energy source. There is often a reduction in hunger on this diet, and perhaps less reduction in energy burn with weight loss.
In support of the ketogenic diet, the first piece of science that the JAMA article discusses is a meta analysis of 13 randomized controlled trials that suggested that more people lose weight and keep it off on a ketogenic diet than people on low fat diets.
A reality check on this analysis: The difference in weight between these two groups was only 0.9kg (2 lb) at one year, and when they analyzed the four studies that continued out to 2 years, there was no difference in weight between the groups at all.
The JAMA article also comments on improvements in several metabolic parameters – but in the meta analysis, the only thing that was significantly different at 2 years was a small improvement in good cholesterol (HDL).
The article goes on to discuss the potential benefits of the ketogenic diet to people with type 2 diabetes. I am very glad to see that they point out that medications like insulin and some oral medications for diabetes can cause low blood sugars, and have to be adjusted to avoid low blood sugars.
However, nowhere do I see mention of safety issues for people on SGLT2 inhibitors [canagliflozin (Invokana), dapagliflozin (Forxiga), empagliflozin (Jardiance)] – as blogged previously, there is a low risk of diabetic ketoacidosis (DKA) with these medications, and that risk could be increased on the ketogenic diet. Some people with type 2 diabetes who require multiple doses of insulin per day may also have quite low to absent insulin production of their own, which could be a recipe to increase the risk of DKA on the ketogenic diet.
My third concern about this article is that it suggests that the lifestyle change to a ketogenic diet may not need to be permanent, and that some people may be able to add back a limited amount of carbs. To me, this encouragement goes against the foundation of long term successful weight management – that lifestyle changes made to manage weight should be permanent changes that can be sustained lifelong. I’m concerned that this opens the door to the yo-yo weight pattern that is consequent to trying a diet plan that is not permanent nor sustainable for many.
Finally, they include an image of coconut oil in their article. Seriously? As blogged previously, coconut oil is actually one of the least healthy oils you can eat.
I do appreciate that the ketogenic diet can work for some people. Avoiding carbs helps to avoid a lot of the unhealthy and quick-grab food that permeates our society, from muffins to burgers to snacks at the grocery store checkout.
We also know that what will work for one person is very different from the next. So while the meta analysis shows no difference in weight on the ketogenic vs low fat diet at 2 years, there will be people within each of these groups who had success, and others who did not.
I also appreciate that the authors of the JAMA article note that “this is not a do-it-yourself-diet” for both safety and efficacy reasons.
But I do feel that their review of the ketogenic diet is overly optimistic, misses some important safety concerns in people with type 2 diabetes, and gives inappropriate hope that this diet can be a non-permanent approach, when no lifestyle change that is not permanent is unlikely to result in sustained success over the long term.
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