Which is the fastest way to lose body fat: doing cardio training or weight training?
We might assume that just doing cardio training will be the fastest way to lose body fat. It appears so – in cardio you are constantly moving, and often for long periods of time. When weight training, you move much less: generally just a part of your body at each time. And with rest periods between movements.
But then consider the case of short-distance runners. They are generally very muscular, and very lean. And they obviously do a lot of weight training (as well as cardio).
Long-distance runners are skinny and have little body-fat. And they do much less weight training.
This article shows that both cardio and weight training contribute to fat loss.
The question about cardio or weight training then becomes: what is best for your goals?
Oxygen consumption and calories expended
We know that movement equals calories burned, which leads on to fat loss. And this is true. But measuring movement is not actually the way to understand calories burned. The best way to work out calories burned is by check your oxygen consumption.
So if in a 30 minute workout your oxygen consumption doing cardio is the same as lifting weight, you will be close to having burned the same number of calories. Essentially regardless of the activity you have been doing.
But in practice it doesn’t quite work like that. All things being equal, your oxygen consumption in 30 minutes of cardio will be greater than that in 30 minute of weight training.
Consider an 80 kg male performing 30 minutes of weight training. Let’s say he is having minimal rest between sets, and his heart rate is elevated the whole time. He might expend 250 calories doing this.
The same guy would expend 400 calories running at 10 km/hr on the treadmill.
Check out this calculator to work out calories used for any physical activity for your specific height, weight and age.
So clearly for straight-out calories used you are better off on the treadmill than lifting weights (all things being equal). Don’t forget – and many do – that you are still burning calories when lifting weights.
How can you make weight-lifting burn more calories?
Make sure you run out of breath while you do it. Is it possible to get puffed lifting weights? Yes – I for one insist on it. What happens at the end of my last couple of sets of lifting – when I reach highest intensity – is that my body feels like it’s out of oxygen. I actually have a little trouble getting oxygen in, and I’m blowing out a lot. It’s what I’m used to now, and I like the challenge.
I like to limit my rest periods and make sure I'm puffing by the end.
Cardio or weight training for fat loss: there is more to it…
Whilst movement, and length of time in movement, is a factor in calories burned, there are other factors of importance. These factors are:
ONE How fit you are to begin with
As you get fitter, you body adapts in many physiological ways. One improvement that takes place as you get fitter is that your heart rate lowers during a workout for a given oxygen consumption. You stronger heart can now cope easier with the rate of oxygen consumption, and so can manage it by pumping fewer times per minute. What then might happen is that you feel that you can exercise harder. When you push yourself harder , you elevate your (now stronger) heart rate to pre-adaption levels, and so increase your rate of oxygen consumption and therefore expenditure of calories.
So we could say that you can lose weight faster as you learn to keep elevating your heart rate even as you get fit. And this will apply whether you are doing cardio or weight training.
TWO Excess Post Exercise Oxygen Consumption (EPOC)
Research suggests that Excess Post Exercise Oxygen Consumption (EPOC) is greater after weight training than after aerobic exercise. Again, because you are using more oxygen, you are burning more calories.
It is not clear how long EPOC actually lasts for. Some bodybuilding literature suggests you get this effect for up to 24 hours. Recent research suggests that 60 minutes or less is a much more accurate estimate. I’m quite sure that I can feel this EPOC thing after a weight training. To me, it feels like I am ever-so-slightly short of breath for about 20 minutes after finishing. I guess extra amounts of oxygen are required by my muscles while they immediately recover from their work.
EPOC is real, but it doesn’t really help the case of doing weights over cardio for burning calories. Increased EPOC post-weight-training is understood to only burn about 20 to 30 calories. It’s fairly negligible.
THREE Long-term – muscle counts
Metabolic rate is the rate at which the body burns calories. We’ve been talking above about burning calories while exercising. And that is obvious. But the body burns calories just to exist: even when still much energy is being used to perform automatic bodily functions.
Which is where muscle comes in. Having muscle boosts your basal – or stationary – metabolic rate. Think of it as muscles being ‘hungry’ for energy just to continue to exist.
Studies have shown that regular weight training can increase basal metabolic rate by around 15%. Other studies suggest for every 1 kg (2.2 lb) of muscle you have, your body burns around 100 extra calories per day.
So over time, you are in a much better position to keep losing weight, or keep the weight off, if you have grown yourself some extra muscle. So weight training becomes a very useful form of exercise if your timeframe is a little longer.
FOUR More is not always more
To wrap this up, there are a couple of real interesting studies that have been done comparing different types of cardio training, and the affects they have on oxygen consumption and therefore calories expended. Reference: Making Sense of Calorie-burning Claims. By Robert A. Robergs, Ph.D., and Len Kravitz, Ph.D.
In the above study, tests were set up with a healthy and fit female exercising in three different ways: a stationary bike; the same bike with arm ergometrics (like on a cross-trainer); with arm ergometrics only.
So essentially, they tested the result of exercising your legs only, arms and legs, and arms only.
The highest heart rate was recorded for the combination arms and legs exercising, which makes sense as more muscles are being used. But peak (maximum recorded) oxygen consumption was actually higher in legs-only exercising, even though fewer muscles are being used.
So using arms and legs felt like harder work, and produced an increased heart rate for the volume of oxygen used. Cycling-only resulted in a lower heart rate, and that meant that a higher intensity – or higher level of oxygen consumption – could be maintained.
Cycling is an activity where large oxygen exchange occurs at a heartrate that can be maintained for a long time.
The study found that by involving less movement and focusing on only the larger muscles of the lower body, a higher intensity can be created at a given heartrate. And this higher intensity represents more oxygen used and more calories expended.
The end result? My favourite go-to statement about losing weight and getting in shape – it’s the intensity that really initiates the process of burning calories. Whether weight training or cardio training.
So what to do? Cardio or weight training to help lose body fat?
It depends on your goals. If you want to lose weight fast NOW, go for cardio. And make it intense cardio. 20 minutes is enough. But make sure it’s HIIT training. You do want to get to a point during your training where you are using maximum possible oxygen.
If you want to lose weight over the medium to long term (if you have 6 weeks or more), be sure to use cardio and weight training. I recommend alternating weights and cardio. You should only need to do each bodypart once per week in weight training. Again, I would rely on the higher intensity HIIT cardio training.
Of course, incorporating the weights is a massive benefit long-term when looking to continue losing weight, or to help keep it off.
Where does this leave our runner types? I will always prescribe the training style of the short distance athlete. I like the leanness, the muscles, the speed, and the fitness. And producing that physique allows a variety of weight and cardio training.
Check this now
Next time you are working out, check both your breathing rate and your heart rate. Imagine that the greater volume of air you are breathing, the more calories you are burning. Monitor your heart rate too, because keeping your heart rate from getting too high will allow you to stay at that level of exertion for longer.
And the longer you can maintain a large volume of oxygen exchange, the more calories you can burn per workout.