A case series of three European adults on carbohydrate‑restricted ketogenic diets developed LDL‑C levels up to 682 mg/dL, mimicking familial hypercholesterolemia. Re‑introducing modest carbohydrates lowered LDL‑C and ApoB without medication, highlighting the need to consider diet‑related lipid changes before diagnosing genetic hypercholesterolemia.
Study and findings
The authors describe three patients referred for suspected familial hypercholesterolemia (FH) after severe hypercholesterolemia emerged during ketogenic dieting. All three were on carbohydrate‑restricted, high‑fat regimens typical of ketogenic therapy, but none fulfilled every laboratory criterion previously defined for the lean‑mass hyper‑responder (LMHR) phenotype. One individual was overweight before diet initiation, a second had a low‑normal body‑mass index (BMI) at referral, and the third was of normal weight but became markedly underweight while on the diet. Peak low‑density lipoprotein cholesterol (LDL‑C) values ranged from 364 to 682 mg/dL, accompanied by elevated apolipoprotein B (ApoB). When modest amounts of carbohydrate were re‑introduced, both LDL‑C and ApoB declined substantially, and no lipid‑lowering drugs were required.
Clinical interpretation
These observations indicate that ketogenic diet‑associated lipid elevations can exceed the conventional LMHR profile and may be indistinguishable from FH on routine lipid panels. Because ApoB‑containing lipoproteins are mechanistically linked to atherosclerosis, the marked rise in ApoB observed here should not be presumed benign. The rapid reduction of LDL‑C and ApoB after modest carbohydrate re‑introduction suggests that dietary carbohydrate content is a key modifiable factor in this phenotype, even in the absence of pharmacologic therapy. Clinicians encountering extreme LDL‑C elevations in patients on low‑carbohydrate regimens should therefore assess dietary history, weight changes, and secondary causes before labeling the condition as genetic FH.
Limitations and open questions
The report is limited to three cases, preventing any inference about prevalence or risk stratification in broader populations. No genetic testing for FH was reported, so the possibility of co‑existing monogenic hypercholesterolemia cannot be excluded. The abstract does not provide details on the exact macronutrient composition, total energy intake, or duration of ketogenic exposure, all of which could influence lipid responses. Future prospective studies with systematic dietary monitoring, genetic screening, and long‑term cardiovascular outcomes are needed to determine whether diet‑induced ApoB elevations confer the same atherogenic risk as genetically driven FH.
Source
Lechner B, Lechner K, Rubinstein G, Parhofer KG, Vogt A. Severe diet-induced hypercholesterolemia mimicking familial hypercholesterolemia in atypical lean mass hyper-responders on ketogenic diets: A case series. J Clin Lipidol. 2026:S1933-2874(26)00513-1. doi: 10.1016/j.jacl.2026.09.002. PMID: 42772973.