A new study from Stanford Medicine explains why two people can follow the exact same low-carb diet and experience completely different results regarding their cholesterol levels. Research presented at the American Society for Nutrition meeting shows that genetic makeup plays a significant role in how individuals respond to changes in dietary fat intake.
Dr. Alexa Barad led the investigation, utilizing data from the long-term DIETFITS trial. Researchers tracked over 400 adults to see how their bodies processed saturated fats when carbohydrates were replaced in their daily meals. The results show that people with a specific genetic predisposition are much more likely to see their LDL cholesterol rise when they consume higher amounts of saturated fats, such as those found in butter, cheese, and red meat.
This study moves beyond looking at single genetic markers. Instead, the team used a polygenic score that aggregates thousands of minor genetic variations to predict an individual's overall tendency toward higher cholesterol. While this score is currently a research tool rather than a standard clinical test, it offers a clear explanation for why some people see sharp cholesterol spikes on low-carb plans while others see no change at all.
The findings offer practical guidance for anyone considering a change in their eating habits. Relying on universal dietary rules often ignores individual biological differences. Dr. Barad advises that individuals should monitor their blood work before and after starting a new diet to see how their specific body responds. Focusing on heart-healthy fat sources like olive oil, avocados, nuts, and seeds rather than animal fats is another way to mitigate risk.
These results represent a step forward in the field of precision nutrition. Rather than assuming one plan works for every body, this research highlights the importance of matching dietary choices to individual health markers. By paying attention to personal blood tests and adjusting fat sources, individuals can make informed decisions about their health without waiting for complex genetic testing to become widely available.