Aerobic vs. Anaerobic for burning fat

Myth: When you do slow paced cardio you burn more fat.

Fact: When you do slow paced cardio a higher percentage of the calories you use come from fat.

It is widely accepted that burning a higher percentage of fat will burn more fat overall this is just not the case. Burning more calories regardless of where they come from will burn more fat. Your body does not care where the calories come from when you exercise. I would like to explain why slow paced aerobic cardio work is not better than fast paced anaerobic cardio exercise when it comes to burning calories  

The way the percentage of calories used is determined is by a number called the respiratory exchange ratio (RER) or also called the respiratory quotient (RQ). Theoretically when your RER is at .7 you are burning 100% fat and when it is at 1.0 you are burning 100% carbohydrates or sugars. So why does any of this matter? When your heart rate is low and you are performing well below a maximal effort your RER will be closer to .7, when you are at a maximal effort such as in interval training or sprinting this value will be much closer to 1.

Let’s compare jogging at 5mph and burning 300 calories an hour with 60% coming from fat and running at 7.5mph and burning 500 calories an hour with 40% coming from fat. At 5mph you will be burning 180 calories from fat, at 7.5 mph you will be burning 200 calories from fat.  In addition to the fact that you will burn more total calories from fat you are also burning up more glycogen (blood sugar). Your body stores all excess sugars as fat, so by using up those additional calories from carbohydrates you are preventing your body from storing back up calories in the form of fat as well. As you can see fast paced workouts will be superior to slow workouts of the same time length for fat burning. If you need exercise that fits your schedule and gives results fast paced workouts should always be your go to. If you have plenty of time to spare then low intensity steady state (LISS) cardio is quite a bit easier and can improve endurance in a superior fashion than high intensity interval training (HIIT).

This should provide a little clarification about the best ways to lose weight through exercise. With that being said; the best program worked half way will never compare to the worst program worked with 100% commitment so find what works for you and stick with it.  

For more information on designing a training program I can be contacted at 801-448-5692.

References:

Dr. Philip Maffetone - The Big Book of Endurance Training

Jack H. Wilmore, David L. Costill - Physiology of Sport and Exercise

Roger W. Earle, Thomas R. Baechle - NSCA's Essentials Of Personal Training