Sure the thermodynamic reduction of `weight-loss := energy-in < energy-burned` is true, but youre erroneously extending that reduction to assert basically ~variance in outcomes is explained by effort and measurement error~.

Most pointedly, theres a number of studies that measured outcomes from over/under-feeding identical twins [1] or varying exercise in identical twins [2] and found significantly wider variance WITHIN twin pairs than across the whole study. Phrased differently, calorie intake + exercise doesn't predict the outcome of weight even when controlling for hereditary factors, and looking at the geometric mean masks this.

TLDR the same amount of exercise + number of calories in one person doesnt predict the outcome in another. Hence why at-home delivery services doesnt eliminate the need for GLP-1 drugs.

[1]: n=12 twin pairs, Bouchard et al., NEJM 1990. [2]: "Mirror image experiment", Bouchard et al., Obesity Research 1994.