The creator Dr. Idz maintains that Nick Norwitz's claims regarding the safety of high cholesterol on a ketogenic diet rely on the omission of crucial scientific data and a study with biased conclusions.

noli's read

The debate centers on the KETO-CTA study (initially published in 2025 in the journal JACC: Advances) co-authored by Nick Norwitz, which claimed that a sharp rise in cholesterol in lean, active individuals with excellent metabolic health did not worsen arterial plaque over one year. However, Dr. Idz's warnings proved to be entirely accurate: this study was officially retracted in March 2026 due to serious methodological flaws, non-reproducible data, and biased analyses that were not double-blind. Furthermore, experts such as heart health researcher Ron Karlsberg revealed that the participants in this study actually showed a much faster accumulation of plaque in their arteries than healthy control subjects. Contrary to Norwitz's thesis, the current scientific consensus, supported by meta-analyses and large observational studies, robustly demonstrates that very high cholesterol levels promote arterial clogging in the long term, even in athletic individuals. The idea that physical fitness cancels out the risks of excess cholesterol on an extreme ketogenic diet therefore lacks solid evidence. Dr. Idz provides an essential clarification for heart health by exposing these flaws.

the sources

1. 1Gardner CD et al. (DIETFITS) 2018
2. 2Seidelmann SB et al. 2018
3. 3Hu T et al. 2012