Cheat days are usually when you relax the diet rules for one day a week, or for one meal a day and often involve eating whatever you like. They’re popular with dieters as they are said to help people stick to an eating plan better than a total ban on treats.
However, the UBC study researchers said that people on a keto diet should think twice before taking a ‘cheat day’ because just one 75-gram dose of glucose – the equivalent a large bottle of fizzy drink or a plate of hot chips – while on a high fat, low carb 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,” says the study’s senior author Jonathan Little. “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.”
Ketosis is where the body is starved of its preferred fuel glucose and starts to burn its fats stores instead. The researchers wanted to look at what happened to the body’s physiology once a hit of glucose was suddenly reintroduced, as would normally happen with a cheat meal.
For their test, the researchers recruited nine healthy young males and had them consume a 75-gram glucose drink before and after a seven-day high fat, low carbohydrate diet, similar to that of a modern keto diet. They found biomarkers in the blood suggesting that vessel walls were being damaged by the sudden spike in glucose.
“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,” adds Little. “It was somewhat alarming.”
The researchers point out that with only nine individuals included in the study, more work is needed to verify their findings, but that the results should give those on a keto diet a reason to stop and think when considering a cheat day.