This is the narrow kernel of Macfadden’s system and the part that does not rest on the disease-cure mechanism. Among the elements of his regimen, regular exercise and a moderate diet are the components that later mainstream public-health advice also came to emphasise, in contrast to the fasting cure and the rejuvenation promise. It is classified with a surrogate endpoint: physical fitness is a measurable intermediate, not a hard disease or mortality outcome. It is recorded as unreplicated because this bundle cites no controlled study establishing the effect of Macfadden’s regimen; his support for the kernel was his own physique and testimony, not a controlled trial. The classification matters for its limits: this comparatively uncontroversial kernel is what lent the doctrine plausibility, and it was around it that the unsupported claims about curing disease and extending life were built.