Cardio Sucks

Matthews' argument is that most people use cardio as their primary fat-loss tool and get poor returns for the hours spent. Fat loss, on his account, is determined mainly by energy intake, with resistance training doing the work of preserving lean mass, and cardio serving as a supporting variable rather than the engine. The provocative title carries that thesis.

The practical framework follows the approach across his other work. Set intake from bodyweight and activity, keep protein high enough to protect muscle during a deficit, keep lifting heavy so the weight you lose is preferentially fat, and use cardio in whatever form and volume you will actually sustain — with a preference for shorter, higher-intensity interval work on time-efficiency grounds. The book is short, practical and prescriptive, aimed at someone who wants a plan rather than a physiology lesson.

It suits a general reader trying to lose fat who has been doing long, joyless treadmill sessions without much result, and who wants a clearer sense of where effort is best spent.

On evidence, the core positions are consistent with mainstream exercise and nutrition research: energy balance governs weight change, higher protein intake and resistance training help preserve lean mass in a deficit, and interval training can deliver comparable cardiorespiratory adaptations in less time. The framing is where it overstates. Trials comparing interval and steady-state training for fat loss generally find modest differences once energy expenditure is accounted for, so the case against steady-state work is weaker than the title implies. More significantly, cardiorespiratory fitness matters for reasons that have nothing to do with body composition — measures of aerobic capacity are among the stronger correlates of long-term health outcomes in the literature — and a book framed around fat loss undersells that. Take the prioritisation argument, which is sound, without accepting the dismissal of aerobic training that comes attached to it.