If you've recently started the keto diet, you may already be thinking about a cheat day. Considering how restrictive the low-carb and high-fat eating plan can be, it's not surprising that you might feel like you need a little break from following the rules. But according to recent research, we're sorry to say you should probably pass on that cookie or bag of chips every day of the week.
A March 2018 study published in Nutrients looked at the effect that consuming a 75-gram glucose drink (a dose equivalent to a large bottle of soda or a plate of fries) before and after following a seven-day high fat, low-carb diet had on nine participants.
"We were interested in finding out what happens to the body's physiology once a dose of glucose is reintroduced," said study author and doctoral student Cody Durrer in a press release. "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 research team was originally looking for an inflammatory response or reduced tolerance to blood sugar, but results suggested that the keto cheat day could actually lead to damaged blood vessels. While most of us might not think about blood vessel health on a regular basis, experts have long warned that damaged vessels are bad for cardiovascular health and may even put people at risk for serious heart problems later in life.
Senior author Jonathan Little, PhD, said this damage may have to do with the body's metabolic response to extra blood sugar, which can cause blood vessel cells to shed and maybe even die. While this study was small and more research is needed, it should be eye-opening to anyone hoping to indulge in carbs on the weekend while on a diet like keto.
"My concern is that many of the people going on a keto diet — whether it's to lose weight, to treat type two 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, especially if these people are at a higher risk for cardiovascular disease in the first place," said Dr. Little.
He added, "Our data suggests a ketogenic diet is not something you do for six days a week and take Saturday off."
Remember: Always talk to your doctor before starting any new diet, especially a restrictive one like keto.