October 16, 2019

Following The Keto Diet? Here’s Why You Shouldn’t Celebrate That Cheat Day

Photo by Sander Dalhuisen on Unsplash

The Keto diet has become a huge diet trend. It is a low-carb, high-fat diet that aims to put your body in a metabolic state known as ketosis. Ketosis enables your body to use fat for energy, instead of carbohydrates from sugar by producing ketones, or small molecules that are alternative fuel sources for the body when sugar (glucose) is in short supply. Ketones are produced by the liver when you eat very few carbs, moderate amounts of protein, and large amounts of fat.

But many following the diet also celebrate days where they ditch the diet all together and have a “cheat day”. Researchers now say that just one day of not following the diet could cause your body damage. Here’s why.

The Study

Code Durrer, UBC Okanagan doctoral student and study first author reports, “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.”

Researchers recruited nine healthy young males and had them consume a 75-gram glucose drink before and after a seven-day high fat, low carb diet. The diet consisted of 70% fat, 10% carbohydrates and 20% protein.

The Results

“We were originally looking for things like an inflammatory response or reduced tolerance to blood glucose. What we found instead were biomarkers in the blood, suggesting that vessel walls were being damaged by the sudden spike in glucose,” explains Jonathan Little, associate professor in the School of Health and Exercise Sciences at UBCO and study senior author. The culprit? He says the damage is most likely brought on by the body’s own metabolic response to excess blood sugar, which causes blood vessel cells to shed and possibly die.

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When the blood vessels of the healthy, young male participants were analyzed after consuming the glucose drink, the results “looked like they might have come from someone with poor cardiovascular health.”

“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,” he says. “Especially if these people are at a higher risk for cardiovascular disease in the first place.”

Cody Durrer, Nia Lewis, Zhongxiao Wan, Philip Ainslie, Nathan Jenkins, Jonathan Little. Short-Term Low-Carbohydrate High-Fat Diet in Healthy Young Males Renders the Endothelium Susceptible to Hyperglycemia-Induced Damage, An Exploratory Analysis. Nutrients, 2019; 11 (3): 489 DOI: 10.3390/nu11030489