No contest. For fat loss, the best type of exercise is anaerobic.
What is anaerobic exercise? Anaerobic exercises are those which involve relatively short bursts of high intensity such as weight lifting, sprinting, and gymnastics. These exercises require skeletal muscle mass and burn calories inefficiently.
Aerobic exercises, on the other hand, are those that require cardiovascular fitness, energy efficiency and relatively less skeletal muscle mass.
Skeletal muscle mass is your body’s calorie burning source, so, the more skeletal muscle mass, the more calorie burning. So, the more muscled your body, the more calories you are burning – even just sleeping!
Say you currently weigh 150 lbs. and utilize 2,000 calories a day. This includes 1,500 calories required just to keep you alive plus 500 calories you burn performing your activities of daily life. This 1,500 calorie minimum (your “basal metabolic rate”) is what is required to support your current mass (muscle, bones, organs, and fat) plus basic functions such as breathing, digestion, and thought. The additional calories depend upon what you do during the day – in this example 500 calories worth of driving, climbing the stairs in your home, working, etc. Now, let’s add 500 calories of aerobic exercise (“cardio”) such as walking on the treadmill to that and you are burning 2,500 calories per day. So, if you follow other basics of eating right and consume just 2,000 calories per day, you will lose fat. Sounds good, right? Just remember, we added 500 calories of aerobic exercise DAILY.
Compare this to the same you and circumstances but substituting muscle building exercises for walking on the treadmill. Here’s where it gets good. After about a month of weight lifting, that 1,500 calories that was required just to keep you alive increases to 1,700. Why? You now have additional skeletal muscle that has to be supported and therefore uses additional calories, On top of that, your workouts which you used to require 500 calories (whether expended on weight lifting or treadmill) now require 600 calories because you have more muscle to carry, move and utilize. So, instead of burning 2,500 calories per day, you are now burning 1,700+500+600=2,800 calories per day with the only change being substituting anaerobic exercise for aerobic exercise.
This is simple enough so far, and frankly, enough to stop the back and forth between Harvard and Berkeley and amongst trainers and other self-proclaimed fitness gurus. But it gets better.
What if you miss a day of working out? With aerobic exercise, if you don’t do it, then you don’t get any benefit in the form of calories burned. With anaerobic exercise, because you have created more skeletal muscle mass, you are burning 200 calories per day more (without accounting for any increases in activities in daily living resulting, not from a change in activities, but from the increased caloric requirement created by carrying extra skeletal muscle mass while performing the very same activities) JUST FOR BEING ALIVE. You are still burning 200 calories more per day having performed anaerobic exercises and creating skeletal muscle mass than you would be had you performed aerobic exercises for the same period. Again, enough said, right?
There are more subtleties involved in anaerobic training being better than aerobic training for fat loss, but here is one that you may remember from high school biology. First, remember “The Kreb Cycle” (now called “The Citric Acid Cycle”)? When we use the aerobic pathway to utilize energy, we get 36-38 ATP (units of energy) per calorie, and when we use the anaerobic pathway to utlize energy, we get 2-4 ATP. Now, which pathway do we want to use if we are trying to lose fat ? (hint: we want to be INefficient)….The ANaerobic pathway! If we are trying to burn calories – use them up, waste them, get rid of them – we want to get as little energy from them as possible – 2-4 ATP per calorie. Another reason for using the anaerobic pathway. Furthermore, when we get “in shape” cardiovascularly, we get more efficient at utilizing energy (calories–>ATP), and it requires more activity therefore to burn up our energy stores. We can run a marathon better and don’t breathe as hard walking up a flight of stairs but we burn fewer calories to do it.
Take a look at the athletes who are sprinters, gymnasts, and divers and compare their “look” and body composition to that of marathoners and other athletes who do “LSD’” (Long, Slow, Distance) and decide which you would like to look like and choose your exercises accordingly. To lose fat, focus on anaerobic exercise to create or maintain skeletal muscle and limit cardiovascular fitness.