Here’s Why Lifting Weights Is The Most Effective Way To Lose Weight
Want to lose weight? While adding cardio into the mix will help you shed the kilos, lifting weights will help turn fat into muscle.

October 7, 2017

a guy lifting a dumbbell to lose weight

Ponder this scenario: you’ve just received a treasured job offer – a dream situation for your career, in fact – but it comes with a few unusual requirements. You have to go shirtless on the job, millions of people will watch you work that way and, oh yeah, you need to achieve and maintain 10 percent body fat or they’ll fire your ass.

However, because you’re so busy doing this job, you have only 45 minutes, three days a week to exercise. Assuming you take the position, what would you do with that time? Go for a run? Hit the elliptical machine? Search the job boards? Hire a body double?

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This was precisely the predicament faced by Andy Whitfield, who played the lead in the American television drama Spartacus: Blood and Sand (think Gladiator meets 300). He was filmed virtually naked in his Roman skivvies. As you can imagine, he was driven by both vanity and fear every time he looked in the mirror.

You can probably relate. It’s natural to assume that an actor has far more time for exercise than the average guy does. But Whitfield’s schedule probably wasn’t much different from your own. After all, he has a wife and two young children and spent most days on set from 7am to 7pm. “For Spartacus, we committed 100 percent of our production time to creating great scenes,” says Whitfield. “So all the training I did was on my own time. And that’s pretty limited.” Sound familiar?

Now consider that job offer again. If you were Andy Whitfield, what kind of exercises would you do to stay lean on the job? Warning: most people have the answer all wrong.

The Great Aerobic Hoax

For decades, we’ve been told that the best activity for burning kilojoules and fat is aerobic exercise. In fact, you can practically pinpoint the year this idea started to take hold: 1977. That’s when Jim Fixx’s The Complete Book of Running was published. This best-seller popularised the notion of running to improve health and lose weight, and it’s widely credited with kicking off the jogging boom of the Eighties. Hundreds of studies since then have reported that aerobic exercise offers many benefits, from improving markers of heart-disease risk and coping with mental stress to enhancing cognitive function.

That’s all good. But if you’re looking to shed fat, the newest weight loss research will tell you to look elsewhere for your exercise routine. “It’s sort of like a self-fulfilling prophecy,” says exercise and nutrition scientist Dr Jeff Volek. “Any type of exercise burns kilojoules. So if you’re told that running is ideal and you start dropping kilos once you take it up, then you have no reason to believe otherwise.” But Volek’s research gives him good reason to doubt the conventional wisdom about the superiority of aerobic exercise for fat loss.


In one study, Volek and his team put overweight people on a reduced-kilojoule diet and divided them into three groups. One group didn’t exercise, another performed aerobic exercise three days a week and a third did both aerobic exercise and weight training three days a week. The results: each group lost nearly the same amount of weight – about 10kg per person in 12 weeks. But the lifters shed 2.5 more kilograms of fat than those who didn’t pump iron.

The weight they lost was almost pure fat, while the other two groups shed seven kilograms of lard, but also gave up 2.5-plus kilograms of muscle. “Think about that,” says Volek. “For the same amount of exercise time, with diets being equal, the participants who lifted lost almost 40 percent more fat.”

This isn’t a one-time finding, either. Research on low-kilojoule dieters who don’t lift shows that, on average, 75 percent of their weight loss is from fat and 25 percent of it is muscle. That 25 percent may reduce your scale weight – hooray! – but it doesn’t do a lot for your reflection in the mirror. (Can you say “skinny-fat”?) However, if you weight train as you diet, you protect your hard-earned muscle and burn extra fat instead.

Picture it in terms of liposuction: the whole point is simply to remove unattractive flab, right? That’s exactly what you should demand from your workouts.

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The New Science of Kilojoule Burning

There’s one argument for aerobic exercise that has always been rock solid. It’s well documented that an activity like moderate jogging burns more kilojoules than weight training, an activity that is highly anaerobic. In fact, if you go by the numbers you find that even golfing beats out a light circuit workout. But recent research shows a new perspective.

When exercise physiologist Dr Christopher Scott began using an advanced method to estimate energy expenditure during exercise, his data indicated that weight training burns more kilojoules than originally thought – up to 71 percent more. Based on these findings, it’s estimated that performing just one circuit of eight exercises – which takes about eight minutes – can expend 665 to 965kJ. That’s about the same as running at 1.6km per minute pace for the same duration.

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“Exercise physiologists often use the techniques for estimating the energy expenditure of walking and jogging, and apply them to weightlifting,” says Scott. “But clearly, aerobic and anaerobic activities differ, and so too should the way we estimate their energy expenditures.” Scott’s revelation is most certainly a relief to gym rats everywhere, who no doubt wondered why an intense, energy-sapping weight workout supposedly burnt so few kilojoules.

1. The T push-up starts with a dumbbell push-up and then extends to a T, working your abs extra hard.

2. Dumbbell rows can harden your core, back and arms.

3. For this “swing” exercise, you can use either a dumbbell or a kettlebell, and either one or both arms. Your glutes, hamstrings and core benefit.

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Real-world Results

The unfortunate reality is that science is slow. “If we waited around for studies to tell us what works best for fat loss, we’d go out of business,” says certified strength and conditioning specialist Rachel Cosgrove, who co-owns a fitness club with her husband, Alwyn. Over the past 10 years, the Cosgroves have risen to the top of the fitness industry because of their clients’ successes. From the beginning, their programmes were scientifically based. “Starting out, we knew that weight training was necessary to avoid muscle loss, and that it appears to boost your metabolism for hours after you work out,” Cosgrove says. “We also knew that according to studies, higher intensity exercises such as interval training and weight training resulted in greater fat loss than lower-intensity exercise did.”

But from there, the Cosgroves started their own experiments. “As time went by, we began to drop aerobic exercise from our fat-loss programmes altogether. And guess what? Our clients achieved even faster results,” says Cosgrove. Keep in mind that the Cosgroves’ clients aren’t like Biggest Loser contestants. In other words, they don’t have four to six hours a day to work out.

“Our average client has to be in and out of the gym in 45 to 60 minutes and has only two to four days a week to exercise,” she says. “We design workouts to optimise that time.” That’s why the Cosgroves rely on what they call “metabolic circuits”. These are fast-paced weight-training routines in which you alternate between upper-and lower-body exercises. You might compare this type of activity to running repeated bouts of 30-to 60-second sprints. While sprinting has been shown to burn kilojoules at a high rate, it can’t be sustained for long because the muscles in your lower body become fatigued – and that’s even if you’re resting between sprints.

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“But with metabolic circuits, you’re emphasising different muscles in each exercise,” says Cosgrove. “So you can maintain a high-intensity effort for a much longer duration, and with almost no rest.” The result: the muscle saving, kilojoule-burning benefits of intense resistance training and sprints, combined with the non-stop movement of long, steady state aerobic exercise.

It could be the greatest fat-loss workout known to man. Of course, if you try to find evidence of this workout’s effectiveness in the scientific journals, you’ll be disappointed: no one has studied it yet. But researchers like Volek and Scott are beginning to put the pieces together. Just as important, trainers like the Cosgroves are already using this kind of routine to help their real-world clients achieve faster results than ever. And not surprisingly, Andy Whitfield used this approach, too. If you were Whitfield, wouldn’t you?