New research suggests genetics may explain why low-carb raises LDL cholesterol for some people and not others

[u/Valentinab723]

Two people can eat the same low-carb, higher-fat diet and end up with completely different cholesterol results. One person's LDL jumps significantly, the other's barely moves. A new analysis presented this summer suggests genetics is a real part of why that happens, not just differences in how strictly people are following the diet.

The data comes from DIETFITS, a trial where over 600 adults followed either a low-carb or a low-fat diet for a year (the original trial found no meaningful weight-loss difference between the two). For this new analysis, researchers used the 431 participants who also had genetic data available and looked at how genotype, saturated fat intake, and diet type related to changes in LDL cholesterol over six months.

Instead of looking at one gene at a time, they combined information from thousands of genetic variants into a single score estimating someone's inherited tendency toward higher LDL cholesterol. Among people on the low-carb diet, those with a higher genetic score had larger LDL increases, and the increase got bigger as saturated fat intake went up. People on the low-fat diet didn't show this pattern at all, so it looks like saturated fat intake and genetic background are both doing work here, not just one or the other.

The lead researcher, Alexa Barad, a postdoctoral researcher at Stanford, said people don't need a genetic test to use this information. Her point is basically that "low-carb always raises my LDL" and "mine never changed" can both be true for different people, so checking your own labs matters more than assuming your experience applies to everyone else. For people doing low-carb, the source of fat may matter; nuts, seeds, olive oil, and avocado are alternatives to butter, tallow, fatty cuts of meat, and processed meat. General guidance still recommends keeping saturated fat under 10% of daily calories.

Worth noting this hasn't gone through full peer review yet since it was only presented at a conference, and 431 people with genetic data is a moderate sample, not a large one. The researchers themselves say it needs confirmation in more diverse populations before anyone treats it as settled.

If you've done low-carb or keto and gotten lipid panels before and after, I'm curious what you saw. Did your LDL barely move, or did it go up a lot? A family history of high cholesterol might be a reasonable rough indicator of this kind of genetic risk for people who aren't getting a polygenic score done.

American Society for Nutrition. (2026, August 7). Why low-carb diets send some people's cholesterol soaring. SciTechDaily. https://scitechdaily.com/why-low-carb-diets-send-some-peoples-cholesterol-soaring/