Bro science 101: you want muscle you lift. You want to shred you do cardio. Well, not so fast, bro.
A new UNSW study has found you can lose around 1.4 per cent, or around half a kilo, of your entire body fat through strength training alone, which is around the same amount you might lose through cardio.
“A lot of people think that if you want to lose weight, you need to go out and run,” says senior author of the study Dr Mandy Hagstrom, an exercise physiologist and senior lecturer at UNSW Medicine & Health.” But our findings show that even when strength training is done on its own, it still causes a favourable loss of body fat without having to consciously diet or go running.”
The study involved a systematic review and meta-analysis of 58 research papers that used highly accurate forms of body fat measurement (like body scans, which can differentiate fat mass from lean mass) to measure the outcomes from strength training programs. In total the studies included 3000 participants, none of which had any previous weight-training experience.
While the strength training programs differed between studies, the participants worked out for roughly 45-60 minutes each session, 2.7 times per week, for around five months.
So, why has strength training previously been dismissed as a fat-loss strategy? Part of the reason is inaccurate ways of measuring fat, says Hagstrom.
If you’re like most people you probably focus on the number you see on the scale – your total body weight. But this figure doesn’t distinguish fat mass from everything else that makes up the body, like water, bones and muscles.
“More often than not, we don’t gain any muscle mass when we do aerobic training,” says Hagstrom. “We improve our cardiorespiratory fitness, gain other health and functional benefits, and can lose body fat. But when we strength train, we gain muscle mass and lose body fat, so the number on the scales won’t look as low as it would after aerobics training, especially as muscle weighs more than fat.” Basically, the scales lie.
While the findings are encouraging for fans of shifting iron, the best approach if you’re aiming to lose fat is to eat nutritiously and have an exercise routine that includes both aerobic/cardio and strength training.
But if cardio just isn’t your thing, you don’t need to force it, says Hagstrom.
“If you want to exercise to change your body composition, you’ve got options,” she says. “Do what exercise you want to do and what you’re most likely to stick to.” Amen to that, bro.