In this case report, Nicholas Norwitz, Dave Feldman, and colleagues describe a man in his 30s who developed extremely high cholesterol after adopting a ketogenic diet to treat ulcerative colitis. His LDL cholesterol rose from 95 mg/dL to as high as 574 mg/dL, with total cholesterol exceeding 700 mg/dL for nearly seven years. Despite these levels, advanced coronary CT imaging found no detectable plaque, stenosis, or calcification, placing him in the lowest percentile for atherosclerotic burden.

The patient fit the profile of a “lean mass hyper-responder” (LMHR): lean, athletic, insulin-sensitive individuals who sometimes experience dramatic LDL increases on carbohydrate-restricted diets alongside high HDL and very low triglycerides. The authors argue this phenotype may reflect an adaptive shift in energy transport during fat-based metabolism rather than conventional metabolic disease, and note that emerging LMHR research has not shown LDL and ApoB levels alone to predict plaque progression as expected.

While the paper does not claim high LDL is harmless, it pushes back on the assumption that LDL cholesterol alone determines cardiovascular risk independent of metabolic context, and calls for more research into how metabolic health and lipid metabolism interact in determining actual cardiovascular risk.