BackgroundKetogenic diet therapies can improve seizure control in patients with drug-resistant epilepsy (DRE). The current study investigated whether dietary fat composition is associated with elevations in serum lipid levels in adults with epilepsy who began a modified Atkins diet (MAD). MethodsAdults with DRE were instructed to follow the MAD. Food records collected at baseline and follow-up were analyzed to extract median daily macro- and micronutrient composition. Total cholesterol (TC), low-density lipoprotein (LDL) cholesterol, triglyceride (TG), high-density lipoprotein (HDL) cholesterol, non-HDL and TC/HDL ratio were measured at baseline and follow-up. ResultsStudy participants initiating MAD showed higher fat intake at 1 month (p<0.001) and 2 months (p<0.001) and lower carbohydrate intake at 1 month (p<0.001) and 2 months (p<0.001) compared to baseline. Study participants also showed higher intake of cholesterol (p<0.001), saturated fatty acid (p<0.001) and monounsaturated fatty acid (p<0.001) over time. Following MAD initiation, study participants showed significant increases in levels of TC (p = 0.007), LDL (p<0.001), and non-HDL (p = 0.009) over time. Dietary intake variables, including cholesterol and fat subtypes, were significantly associated with difference in 1 month TC and LDL levels from baseline but not absolute 1 month lipid values. In a sub-analysis, participants with baseline dyslipidemia showed smaller changes in lipid values during diet use. ConclusionsAdults with DRE starting MAD increased fat intake, particularly saturated and monounsaturated fat subtypes, and reduced carbohydrate intake. Changes in TC and LDL levels 1 month after MAD initiation are associated with dietary intake of cholesterol and fat.