Built on years of fieldwork with the Hadza in Tanzania, who hunt and forage all day and, measured properly, burn about the same daily calories as an office worker in Toronto.
That is the whole book. Total energy expenditure is constrained rather than additive. Exercise more and the body reallocates the budget somewhere else rather than raising the total.
Which means exercise is close to useless as a weight loss strategy and essential for almost everything else. The calories do not come off the way the treadmill display claims. The cardiovascular, inflammatory and metabolic benefits are real.
I found this genuinely clarifying, mostly because it explained why a decade of swimming never did what I assumed it would for the scale.
Read February 2023.