Abstract
KEY CLINICAL MESSAGE: Although the lean mass hyper-responder (LMHR) phenotype is well known, its diagnosis is impeded by the influence of fat type and intake on the lipid profile. Accordingly, a detailed assessment is warranted if LMHR is suspected. ABSTRACT: A 47-year-old man with suspected familial hypercholesterolemia presented with elevated triglyceride and low-density lipoprotein cholesterol levels. He had adhered to a ketogenic diet and was suspected of a lean mass hyper-responder phenotype; however, his lipid profile did not meet the definition. His lipid profile improved through dietary management without medication.