Take the stairs, park farther away, get your steps in, burn it off. Exercise gets sold as the main way to lose weight. But when you dig into the research, it does a lot less for the number on the scale than most people expect, and a lot more for nearly everything else. Nick and Zoë start with what happens when people actually start exercising. A well-controlled trial put young adults through 10 months of supervised workouts and saw modest weight loss. A year-long study of postmenopausal women found that most of the change came from diet. Part of the reason is that our bodies and brains adjust. We get hungrier, we move a little less the rest of the day, and something as small as seeing a calorie count on a screen, or calling a workout "fat-burning," can change what we eat afterward. That's not an argument against exercise. It's an argument for measuring it by more than the scale. Zoë and Nick talk about why the exercise you enjoy will always beat the "optimal" one, why the cardio vs. strength debate is mostly noise, and what extra muscle does and doesn't do for your metabolism. They also cover a meta-analysis of nearly 400,000 people suggesting fitness may say more about long-term health than weight does, and what researchers learned from The Biggest Loser about the costs of chasing weight loss at any price. Plus, why no amount of crunches will choose where your body loses fat, and how each of them got into exercise in the first place and kept at it. In The Fine Print, Nick finds a soy milk labeled "packed with protein" that has less protein than the regular version, which raises the question of what a "high protein" label actually requires. And in this week's Unforced Error, they look at the Babydust Method and whether timing sex can really decide whether you have a boy or a girl. Referenced: Donnelly et al., Midwest Exercise Trial 2, Obesity (2013) Foster-Schubert et al., diet and exercise in postmenopausal women, Obesity (2012) McCaig, Hawkins & Rogers, "Licence to eat," Appetite (2016) Fenzl et al., "Labeling exercise fat-burning increases post-exercise food consumption in self-imposed exercisers," Appetite (2014) Weeldreyer et al., cardiorespiratory fitness, BMI and mortality, British Journal of Sports Medicine (2025) Fothergill et al., metabolic adaptation six years after The Biggest Loser, Obesity (2016) Vispute et al., "The Effect of Abdominal Exercise on Abdominal Fat," Journal of Strength and Conditioning Research (2011) Panteleimon Ekkekakis's research on exercise and enjoyment Wilcox, Weinberg & Baird, timing of intercourse and sex of the baby, NEJM (1995) Gray et al., sex ratio and timing of insemination, Human Reproduction (1998) Nick Tiller, The Skeptic's Guide to Sports Science
