Your genes may determine how a low-carb diet affects cholesterol
New research suggests genetics help explain why low-carb diets raise LDL cholesterol sharply in some people while leaving it unchanged in others. Saturated fat intake appears to interact with genetic predisposition to drive the difference.
Low-carbohydrate diets have grown increasingly popular, yet their effect on cholesterol varies widely from person to person — some see barely any change, while others experience a sharp rise. Researchers led by Alexa Barad, a postdoctoral scholar at Stanford University School of Medicine, now suggest that genetic makeup helps explain this variation, particularly through its interaction with saturated fat intake.
The findings were presented at NUTRITION 2026, the annual meeting of the American Society for Nutrition. The analysis drew on data from DIETFITS, a randomized controlled trial in which more than 600 adults followed either a healthy low-carb or low-fat diet for a year. The original trial found no significant weight-loss advantage between the two diets. For this new analysis, researchers examined genetic data from 431 participants, looking at how genotype, saturated fat consumption, and diet type related to changes in LDL cholesterol after six months.
Genetics and saturated fat combine to raise risk
Among participants on the low-carb diet, those genetically predisposed to higher LDL cholesterol were more likely to see it rise, especially when they consumed more saturated fat. This pattern did not appear among people following the low-fat diet. Rather than looking at single genetic variants as earlier studies did, the researchers combined thousands of variants into a polygenic score to estimate each participant's overall genetic tendency toward higher or lower LDL cholesterol.
Barad said the results show real heterogeneity in how people respond to diet, meaning that a person whose LDL rises on a low-carb diet and one whose LDL stays flat can both be describing accurate experiences, shaped in part by their genetic background.
Genetic testing is not required to apply a practical lesson from the study: individuals should monitor how their own body responds to dietary changes rather than assuming a uniform outcome. For those following a low-carb diet, Barad recommended favoring nuts, seeds, olive oil, and avocado over foods high in saturated fat, such as butter, fatty meat cuts, and processed meats. Current guidance recommends keeping saturated fat under 10% of daily calories. The findings have not yet undergone peer review and are considered preliminary pending further research across more diverse populations.
