A UNSW Sydney study published in Sports Medicine suggests that fat-loss is not only possible with strength training but is equal to the results achieved with cardio fitness. It's a myth-busting revelation that refutes the basic premise that to gain muscle, you strength train, and to lose fat, you do cardio.

The study – a systematic review and meta-analysis that evaluated and analysed existing evidence – shows we can lose around 1.4 per cent of our total body fat through strength training alone, similar to how much we might lose through cardio or aerobics.

"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, 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."

Up until now, the link between strength training and fat loss has been unclear due to small sample sizes, which make it difficult to find statistically significant results, especially as many bodies can respond differently to exercise programs.

"It can be really difficult to discern whether there's an effect or not based on one study alone," says Dr Hagstrom. "But when we add all of these studies together, we effectively create one large study and can get a much clearer idea of what's going on."

The study included 3000 participants and 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.

The program lasted for about five months and included strength training programs of roughly 45-60 minutes each session for an average of 2.7 times per week.

The team found that, on average, the participants lost 1.4 per cent of their total body fat after their training programs, which equated to roughly half a kilo in fat mass for most participants.

The results are not surprising to physiotherapist Michael Dermansky, who says its strength training, not cardio, that has long-term positive effects on metabolism.

"Strength training and building muscle mass effectively has a multiplier effect on your metabolism. Unlike cardio training, a repetitive low-load exercise, building more muscle means that everything you do burns more energy.

"It makes your cardio workouts more effective because you burn more energy doing the same level of activity as before, but usually with less effort because you have more muscle mass.

"Cardio exercise is great for improving your heart health, but from a weight management perspective, it should be an adjunct after you have performed your well-structured strengthening program," says Mr Dermansky. 

Strength training also has many other important health benefits aside from being a fat-loss tool, explains Dr Hagstrom.

"Resistance training does so many fantastic things to the body that other forms of exercise don't, like improving bone mineral density, lean mass and muscle quality. Now, we know it also gives you a benefit we previously thought only came from aerobics," says Dr Hagstrom.

While the findings are encouraging, Dr Hagstrom says the best approach for people aiming to lose fat is to eat nutritiously and include cardio and strength training exercise. But if aerobics and cardio aren't for you, strength training is the way to go.

"If you want to exercise to change your body composition, you've got options," says Dr Hagstrom.