Why does one person lose weight on a low-carbohydrate diet without any problems while another develops much higher cholesterol?
Scientists have been trying to answer this question for years. New research presented at NUTRITION 2026 suggests that the answer may lie in a person’s genes.
The study was led by researchers from Stanford University School of Medicine. They found that genetic differences appear to change how sensitive people are to saturated fat, which is often eaten in larger amounts on low-carb diets. This sensitivity may determine whether LDL cholesterol rises or stays stable.
LDL cholesterol is often called bad cholesterol because high levels can contribute to plaque building up inside arteries. Over time this increases the risk of heart attack and stroke. However, previous research has produced mixed results, with some people experiencing large increases on low-carb diets while others show little or no change.
To better understand these differences, researchers analysed data from the DIETFITS study. More than 600 adults had been randomly assigned to either a healthy low-fat or healthy low-carbohydrate diet. The new analysis focused on 431 participants whose genetic information was available.
The scientists calculated a polygenic score using thousands of genetic markers rather than relying on a single gene. This approach gave each participant an estimate of their inherited tendency to develop higher LDL cholesterol.
The results showed that people with a stronger genetic tendency toward high LDL cholesterol experienced the biggest increases after eating larger amounts of saturated fat while following a low-carbohydrate diet. This relationship was not seen among people assigned to the healthy low-fat diet.
The findings suggest that future nutrition advice could become much more personalised. Instead of giving identical recommendations to everyone, doctors may eventually use genetic information to predict who is most likely to benefit from certain diets and who may need a different approach.
Even without genetic testing, the researchers say there is an important practical lesson. Anyone making major dietary changes should monitor important health markers such as cholesterol rather than relying only on weight loss or personal stories shared online.
They also recommend choosing healthier fat sources whenever possible. Replacing butter, fatty meat and processed meat with foods such as olive oil, nuts, seeds and avocados may reduce the chance of unwanted cholesterol increases while still following a lower-carbohydrate eating pattern.
The study was presented at a scientific meeting rather than as a completed peer-reviewed journal publication, so additional research will be needed to confirm the findings. Nevertheless, the results provide strong support for the growing idea that nutrition should be tailored to the individual.
Understanding both genetics and lifestyle may eventually help people choose diets that improve health while avoiding unnecessary risks.
If you care about nutrition, please read studies that vitamin D can help reduce inflammation, and vitamin K may lower your heart disease risk by a third.
For more health information, please see recent studies about foods that could sharp your brain, and results showing cooking food in this way may raise your risk of blindness.
Source: Stanford University School of Medicine.
