One of the perennial questions about exercise for weight loss (fat loss) is whether to concentrate on aerobic exercise (cardio) or weight training and resistance exercise. Let's settle this right up front: You should do both, concurrently, for best outcome. It makes sense, and it is what most serious, natural bodybuilders do to get a ripped, lean body.
Scientific studies pop up from time to time showing a certain level of fat loss with cardio versus weights -- and for the most part cardio outperforms weights in any reasonable comparison. There is no secret to this because continuous movement at a reasonably demanding intensity and volume will always outperform intermittent exercise, even at high intensity, and even accounting for the "afterburn". Ultimately, you need to do both. Here's how it works.
Advantages of Weights for Fat Loss
Strength and resistance training builds muscle. Muscle has a higher metabolic rate than fat so having more muscle raises your resting metabolic rate (energy expenditure) a little compared to having more body fat. However, the differences are not dramatic; perhaps less than a few dozen calories per day for each pound of muscle increased, for most people. That helps, but it's not life-changing. Even so, in a weight loss program, weight training is important to help maintain muscle. When you lose weight is tends to be a combination of fat and muscle. You want to lose the fat but hold onto the muscle for the reasons described above. Weight training helps you achieve this, and has many other benefits for health and performance, besides building extra muscle.
So, extra muscle does not provide that much advantage in energy expenditure, but what about the afterburn, long touted as an advantage of weight training? The 'afterburn', is the amount of energy you use after you stop exercising. This is another way of saying your metabolism increases for several hours or longer after an exercise session. Exercise scientists call this afterburn effect EPOC, which stands for Excess Post-exercise Oxygen Consumption. The thing is, afterburn happens when you exercise at higher intensities -- greater than about 75 percent of maximum heart rate -- whether it's weights or cardio. However, you need to be able to sustain that intensity, which means a lot of hard work.
Advantages of Cardio for Fat Loss
The main advantage of aerobic exercise at moderate intensities is that you can do it continuously for much longer than the intermittent exercise of lifting weights. It is this non-stop movement that gives cardio a inherent advantage in energy expenditure during an exercise session. Yes, you can mix weights and movement in circuit training sessions to provide that extra boost, but movement is the key, and if you move fast enough to the point where you are running or cycling at around 80% of maximum heart rate, you will get some afterburn as well. That's why most comparisons show cardio to be superior to traditional weight training for energy expenditure.
Of course, cardio is the best exercise for cardiovascular and cardiorespiratory (heart and lung) fitness.
The Best Program for Fat Loss and Muscle Maintenance
where are we at with our exercise and weight loss project? Here is a summary.
- Increase muscle with weight training. Extra muscle helps to burn more energy at rest, even if only a little.
- Lift heavier weights. The weights workout should be vigorous, with the number of repetitions kept at the low to medium end of the scale between 8 and 12 repetitions. (The RM is the repetition maximum, which means the most weight you can lift for this number of reps before fatigue.)
- Combine resistance training with continuous movement in a circuit training program or a similar anaerobic training program in which you work out on progressive workstations at a moderately high intensity.
- If you go higher than this, say 15 to 20 repetitions to a set, or more, you are getting into the range where you would probably be better off doing cardio because the return on effort, the energy burn, is better spent jogging, cycling, stepping or rowing. At that number of repetitions you won’t build much muscle either, so very high-repetition training with weights has minimum value in my view.
- Do regular aerobic exercise of your choice, with jogging and cycling preferable to swimming or walking for maximum calories burned in shorter time. Considering how much energy you would use in an hour of either static weights or cardio, you must do some consistent aerobic or cardio work to burn fat. Try alternating weights and cardio days for 6 days each week.
- Do high-intensity cardio for shorter elapsed times, or try high-intensity interval training. High-intensity exercise, even if only in short bursts, may rev up the metabolism and get that fat mobilized in the post-exercise period. However, don’t overdo it, because burning fat is a long-term project and you don’t want to get ‘burned out’. A group exercise program such as a solid cycle spin class might match this requirement.
For best weight loss success in your exercise program, combine weights and cardio and a little high-intensity interval training when you get fitter and you can manage it. That's the success secret of exercise for weight loss.