A two-year study from Norway shows that a low-carb diet high in saturated fat has mixed effects on cholesterol levels. The trial, called CARBFUNC, found that while LDL cholesterol increased slightly, it was due to larger, less harmful particles.
The study, led by Professor Simon Dankel and published in eBioMedicine, involved 193 adults with obesity in western Norway. Participants were randomly assigned to one of three diets and followed for up to two years.
High saturated fat intake shows surprising results
One group consumed a diet high in total and saturated fat but very low in carbohydrates (under 10% of energy). The other two groups followed a more standard diet with carbohydrates from either refined or minimally refined sources.
All diets provided a sustained energy intake of around 2,500 calories for men and 2,000 for women. They also specified the same protein intake, reduced added sugar to 1%–2% of energy, and recommended 500 grams of vegetables per day.
The high-fat diet group saw a 5%–10% increase in LDL cholesterol, primarily due to larger particles. Cathrine Loddervik, the study’s first author, noted that small, dense LDL particles—which pose a greater risk—did not change significantly.
The study also found that triglycerides decreased by 20%–35% and HDL cholesterol increased by 5%–18% in the low-carb group. These changes are linked to improved insulin resistance and metabolic health.
No increase in coronary artery calcification
Researchers used CT scans to examine calcium deposits in coronary arteries at the start and after 12 months. They found no clear increase in deposits on the high-saturated-fat diet, with no difference between diet groups.
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The carbohydrates in the diets were primarily whole grains, known for a more favorable blood lipid profile. The high-fat diet largely excluded grains.
Long-term effects of high saturated fat intake
The CARBFUNC trial is unique in its approach, as no previous study has prescribed such a high intake of saturated fat over two years. The diet consisted of nearly a third of energy from saturated fat, far exceeding the typical recommendation of less than a tenth.
Implications for cardiovascular health
Loddervik explains that the moderate increase in LDL cholesterol should be interpreted in the context of other blood lipids and metabolic health. The favorable changes in triglycerides and HDL cholesterol in the low-carb group further support this perspective.
The absence of a clear increase in coronary artery calcification on the high-saturated-fat diet is another notable outcome. CT scans revealed no significant difference in calcium deposits between the diet groups after 12 months.
The study’s DOI is 10.1016/j.ebiom.2026.106524, and it was published in eBioMedicine in 2026.
ApoB levels remain stable on high-fat diet
Researchers observed that apoB levels neither increased nor changed appreciably differently from the two diets with more carbohydrates and less fat. This stability in apoB levels is notable, especially considering the high intake of saturated fat in the diet.