I take objection to that. The statistician isn't the person who demands certainty and precision and will be more aware of the risk of deeper water than the other. Practically all medical science is predicated on probabilities and confidence intervals.

Every person is not going to have metabolic efficiency between 18% and 26% but the odds are very strong that a given individual will. Especially if we're willing to account for extreme outliers, and reasonably consider healthy adults having decent medical care, reasonable diet, at least moderate levels of physical activity etc.