Cheat days are a popular indulgence on many diets, including the ketogenic diet. Yet, emerging research reveals that a single 75-gram dose of glucose—comparable to a large soda or plate of fries—during a high-fat, low-carb regimen can impair blood vessel health.
In this study, researchers enlisted nine healthy young men to drink 75 grams of glucose both before and after following a seven-day high-fat, low-carb diet mirroring modern keto protocols: 70% fat, 10% carbohydrates, and 20% protein.
"We initially sought signs of inflammation or reduced glucose tolerance," notes the lead researcher. "Instead, we detected blood biomarkers indicating damage to vessel walls from the abrupt glucose surge."
The likely mechanism? The body's reaction to excess blood sugar, which prompts blood vessel cells to shed and potentially die.
"Despite these men being young and healthy, post-glucose tests showed vascular health akin to someone with cardiovascular issues," the researcher adds. "The findings were striking."
"Keto followers—whether managing weight, type 2 diabetes, or other conditions—risk undoing vascular benefits with sudden glucose spikes, especially if predisposed to heart disease," he warns.
"The evidence points to keto as a consistent commitment, not a six-day plan with a day off."
