UBC study reveals cheat day in popular diet may cause some harm

A UBC Okanagan study into a popular diet has revealed that a cheat day could be bad for your health.

The researchers said that people on the so-called keto diet should think twice before taking a ‘cheat day.’

According to the researchers, a ‘cheat day’ is a common theme in many diets and the popular ketogenic diet, or keto as it’s better known, is no exception.

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But according to new research from UBC Okanagan researchers, just one 75-gram dose of glucose — the equivalent a large bottle of soda or a plate of fries — while on a high fat, low carbohydrate diet can lead to damaged blood vessels.

“The ketogenic—or keto—diet has become very common for weight loss or to manage diseases like type 2 diabetes,” said Jonathan Little, associate professor in the School of Health and Exercise Sciences at UBCO and study senior author.

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“It consists of eating foods rich in fats, moderate in protein, but very low in carbohydrates and it causes the body to go into a state called ketosis.”

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Little said the diet can be effective because once the body is in ketosis and starved for its preferred fuel, glucose, it begins to aggressively burn its fat stores.

This leads to weight loss and can reverse the symptoms of diseases like Type 2 diabetes.

“We were interested in finding out what happens to the body’s physiology once a dose of glucose is reintroduced,” said Cody Durrer, a UBC Okanagan doctoral student and study first author.

“Since impaired glucose tolerance and spikes in blood sugar levels are known to be associated with an increased risk in cardiovascular disease, it made sense to look at what was happening in the blood vessels after a sugar hit.”

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The researchers used nine healthy young males for their study.  The young men consumed a 75-gram glucose drink before and after a seven-day high fat, low carbohydrate diet. The diet consisted of 70 per cent fat, 10 per cent carbohydrates and 20 per cent protein, similar to that of a modern ketogenic diet.

“We were originally looking for things like an inflammatory response or reduced tolerance to blood glucose,” Durrer said. “What we found instead were biomarkers in the blood suggesting that vessel walls were being damaged by the sudden spike in glucose.”

The researchers acknowledge that with only nine individuals in the study, more work is needed to verify their findings. But they added the results should give those on a keto diet something to think about when considering a cheat day.

“My concern is that many of the people going on a keto diet—whether it’s to lose weight, to treat Type 2 diabetes, or some other health reason—may be undoing some of the positive impacts on their blood vessels if they suddenly blast them with glucose,” Durrer said.

“Especially if these people are at a higher risk for cardiovascular disease in the first place. Our data suggests a ketogenic diet is not something you do for six days a week and take Saturday off.”