Kelowna, British Columbia, Canada—Taking a cheat day on a keto diet could be harmful, potentially leading to damaged blood vessels, suggests a new study from the University of British Columbia’s Okanagan (UBCO) campus.
Cody Durrer, UBCO doctoral student and study first author, said in a press release from the university, “We were interested in finding out what happens to the body’s physiology once a dose of glucose is reintroduced. 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.”
The study was small, the press release notes: Participants were nine healthy young males, who consumed a 75-gram glucose drink before and after a seven-day high fat, low carb diet, which had the same ratio as a ketogenic diet.
“We were originally looking for things like an inflammatory response or reduced tolerance to blood glucose,” Durrer said in the release. “What we found instead were biomarkers in the blood suggesting that vessel walls were being damaged by the sudden spike in glucose.”
Jonathan Little, associate professor in the School of Health and Exercise Sciences at UBCO and senior author on the study, said that the most likely culprit for the damage is the body’s own metabolic response to excess blood sugar, which causes blood vessel cells to shed and possibly die. In the release, he said, “Even though these were otherwise healthy young males, when we looked at their blood vessel health after consuming the glucose drink, the results looked like they might have come from someone with poor cardiovascular health. It was somewhat alarming.”
Dieters on keto, therefore, might want to think twice about taking a cheat day—or even just a cheat meal.