Diabetes Healthy Eating Kidney & Renal

Keto diet “cheat day” study leaves St. Paul’s dietitians hungry for more research

A keto diet is high in fats but low in carbohydrates

A new study finding that “cheat days” could harm the blood vessels of those on a keto diet is an interesting angle to this popular diet, say two dietitians at St. Paul’s Hospital in Vancouver.

However, the need for a cheat day from a diet that eliminates entire food groups makes them question how sustainable the diet really is.

“That said, we realize this is preliminary research and we can’t draw conclusions on it just yet,” says Tanya Choy, Registered Dietitian at St. Paul’s.

A keto, or ketogenic, diet is very high in fat, moderate in protein and very low in carbohydrate. The severe carb restrictions place the body into a state of ketosis by burning fat instead of carbohydrate as an energy source. It’s  been linked to rapid, short-term weight loss.

The study, by researchers at the University of BC Okanagan and profiled on Global TV this week, involved nine healthy males participants. They consumed a 75-gram sugary drink before and after a seven-day high fat, low carbohydrate diet. The diet consisted of 70 per cent fat and 20 per cent protein. Carbs were limited to 10 per cent. The ratios are similar to the keto diet.  

The researchers acknowledge that the sample size of just nine subjects is small, notes St. Paul’s dietitian Emily Zamora.

She adds, “We wonder if the researchers took a baseline measure of the blood vessels before they offered the participants the sugary drink. Whether subjects entered a state of ketosis was not measured, likely because this study only called their test diet a “low-carbohydrate, high-fat diet” (vs. a keto diet).”

“As we have said in the past, the ketogenic diet is not a balanced or sustainable way of eating,” say the dietitians.

They add that the need for the “cheat days,” where those on the diet find they need to load up on carbs once every so often, makes this very point.

Cheat days also separate food into “good” and “bad” categories and in our view that does not foster a positive relationship with food,” says Choy.

Choy and Zamora they don’t know the long-term effects of a low-carbohydrate, high-fat diet on health. They are concerned it eliminates whole food groups and that in turn can lead to vitamin and mineral deficiencies. It also requires planning and calculation and can affect the social aspects of eating out and with others.

And they say people living with diabetes must take extreme caution if they go on this type of diet, as complications could increase. “Without collaboration with a health care professional who is specialized in nutrition and diabetes, we would not recommend this diet.”

Choy and Zamora look forward to more studies on the overall impact of this diet as well as further research on the effects on blood vessels.


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