Why might a low-carb diet raise LDL more in some people?

News summary

ScienceDaily opened this story with a familiar question: why can two people follow similar low-carbohydrate diets while one sees LDL cholesterol rise sharply and the other barely changes? The researchers performed a secondary analysis of DIETFITS, a dietary trial that compared healthy low-fat and healthy low-carbohydrate eating patterns, using data from 431 participants. People with a stronger genetic predisposition to high LDL tended to have larger LDL increases on the low-carb diet when saturated-fat intake also rose. The news takeaway was that responses to the same diet can differ substantially between individuals, and both genetics and the type of fat eaten may help explain why.

Within the low-carbohydrate group, people with greater genetic predisposition to high LDL tended to show larger LDL increases as saturated-fat intake rose. The same pattern was not observed in the low-fat group. The researchers used a polygenic score, which combines information from many genetic variants into an estimate of inherited LDL susceptibility.

The finding argues against a one-size-fits-all view of diet. Even without genetic testing, there is a practical lesson: LDL should be monitored after major dietary changes, and fat quality matters. A low-carb diet built around unsaturated rather than saturated fats may reduce the chance of an unfavorable lipid response.

This was a secondary analysis and needs replication in larger, more diverse populations. ScienceDaily explicitly notes that the findings were presented at NUTRITION 2026, a scientific nutrition meeting, and should be considered preliminary rather than equivalent to a fully peer-reviewed definitive paper. Genetics is also only one contributor to individual LDL response.