Those on keto diet should think twice before having a "cheat day." Findings of a new research show that consuming just a plate of fries or a large bottle of soda while on the popular high fat, low carbohydrate diet can damage the blood vessels.

The Ketogenic Diet

The ketogenic, or keto diet, involves eating foods rich in fats, moderate in protein, and very low in carbohydrates. It causes the body to go into a state of ketosis when it burns fat instead of glucose.

Many touted the benefits of keto for weight loss and management of diseases.

Jonathan Little, from the University Of British Columbia Okanagan Campus, said the diet is very effective for losing weight because once the body is in ketosis and no longer has enough glucose, its default fuel, the body's chemistry changes and starts to aggressively burn fat stores.

This in turn also reverses symptoms of diseases such as Type 2 diabetes.

Sudden Spike In Glucose Levels May Damage Blood Vessels

Little and colleagues wanted to find out what happens to the body once a dose of glucose is reintroduced while on keto.

They recruited nine participants who consumed a 75-gram glucose drink after a week of high fat, low carbohydrate diet consisted of 70 percent fat, 20 percent protein, and 10 percent carbohydrates, similar to that of the keto diet.

The researchers found biomarkers in the blood that suggest the blood vessel walls were being damaged by the sudden spike in glucose levels.

"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," Little said. "It was somewhat alarming."

Little said the possible culprit for this damage is the body's metabolic response to excess blood sugar that causes the blood vessel cells to shed and possibly die.

Cheat Day May Undo Positive Impacts Of Keto

The researchers acknowledged more work is needed to confirm the findings, but the study should at least caution those on keto diet about cheat days.

The findings suggest people may undo the positive impacts of the diet with sudden increase in glucose intake.

"In conclusion, one week of low-carbohydrate high-fat feeding that leads to a relative impairment in glucose homeostasis in healthy young adults may predispose the endothelium to hyperglycemia-induced damage," the researchers wrote in their study.

The findings were published in the journal Nutrients on Feb. 26.