Keto and Cholesterol: A Fat-Burning Paradox

While diet plans come and go, low-carbohydrate, high-fat, ketogenic “keto” diets have retained their staying power for more than 20 years. But does following a diet centered on consuming foods high in fats such as meats, eggs, and oils raise heart disease risk? Cholesterol levels are an index of heart disease risk, as excess cholesterol can contribute to plaque buildup in coronary arteries. A recent meta-analysis of 41 human trials investigating the physiological effects of a keto diet revealed surprising information about the diet’s impact on "bad" low-density lipoprotein (LDL) cholesterol levels. Overweight people following the keto diet for weight loss had no change in their LDL over time. However, this diet is also popular among lean people seeking a high-protein diet to build muscle. When following a keto diet, these individuals LDL cholesterol levels often rise to an unhealthy level, giving rise to the novel “lean mass hyper-responder” (LMHR) phenotype.

The team found that for those in the LMHR group, several years of carbohydrate restriction-induced elevations in LDL cholesterol did not increase their coronary plaque burden, relative to controls as detailed in JACC: Advances. Nasir noted, “LMHR is an emerging phenotype of growing research interest with little known about mechanisms and risks. Clinicians’ awareness of the unique aspects of LMHR may facilitate more personalized patient management.”