To run in winter, you should dress as if the outdoor temperature is higher than it actually is: you should feel a slight chill when you head out, because the body generates its own heat after a few minutes of exertion.

noli's read

This advice is based on the physiology of thermoregulation during exercise. When running, muscles produce a significant amount of metabolic heat (about 70 to 80% of energy expended is dissipated as heat), which justifies not aiming for immediate thermal comfort while standing still. Observations in the field of sports physiology (notably the recommendations of the American College of Sports Medicine) confirm that dressing too warmly leads to excessive sweating, dampening of clothing, and subsequent rapid cooling as soon as intensity decreases. The rule of dressing as if it were 5 to 10°C warmer than the actual temperature is an empirical consensus commonly used by running coaches. It is not an absolute truth, as it depends on the intensity of the effort (interval training vs. endurance running) and individual cold tolerance. The advice is therefore very robust from a practical standpoint to avoid overheating, while remaining a customizable approach.

the sources

No named source held this one up — that absence is part of the verdict.