Weight Loss

Why is it that when I do an 18-20 minute mile I burn 30-35% fat and when I do a 15-16 minute mile I burn only 20% fat? This has been bothering me for awhile now.   I  just did a 15.5 minute mile and burned less fat than when I go a lot slower.  Anyone else notice this?

2 points:

1) calories burned is what's important, it doesn't matter where they come from.  If you burn a bunch of calories from the sugar stored in your muscles then when the workout stops your body will use it's fat stores to replace that sugar.

2) You burn more calories at a higher speed, so even if the percentage of calories from fat is lower, the total calories from fat may well be higher.

I'm confused - sorry!!! so if I bike faster I will burn more calories but less fat?

Calories turn into fat.

So burning calories is like indirectly burning fat...

Do the exercise that burns most calories!

it's not about speed - it's about exertion.  there's no point going faster if it means you're going to quit after ten minutes, but going faster for the same length of time (not distance) will burn more energy.  a leisurely walk isn't going to burn much if you're fit enough to double your pace, but if slow is the best you can do, going slower is better than not going at all.

Original Post by pgm012197:

I'm confused - sorry!!! so if I bike faster I will burn more calories but less fat?

 When you exercise (or when you do anything for that matter) your body needs energy (calories).  This energy can come from one of two sources, glycogen or fat.  Different exercise intensities can burn different percentages of each, for example walking slowly might burn 100 calories/hour and half of them might be from fat and half from glycogen.  However, running might burn 200 calories/hour and might burn a lower percentage of calories from fat (say 40%), you'd then burn 80 calories from fat and 120 from glycogen, a lower percentage of calories from fat but more fat calories overall.

None of this really matters though because your body needs to replenish glycogen stores after your workout and can convert fat to glycogen to do this.  So basically more calories = more fat loss.

I am so glad you posted this because I have been confused about this same thing! Thank you, all you super smart CC people!!

My experience is that over the speed range 3-6 mph (walking to jogging), the burn rate per mile is the same - about 70 calories per mile over and above BMR (which for me is about 70 calories per hour). Over the same distance I burn the same calories, and the only difference is the time it takes me to cover the distance. 10 miles burns 700 calories no matter how I do it.

Bicycling is different. The burn rate drops to about 40 calories per mile above BMR. So you need to go almost twice as far to get the same burn.

I'm not sure about the metabolism part, but it was my understanding that the body burns glucose directly from the bloodstream, which is replenished from a reserve of glycogen which is broken down by the liver. The glycogen is replenished from digested food or from fat breakdown. So you don't burn fat immediately when you exercise - the body balances its accounts later, usually when you are sleeping.

Thank you for your explanation!!!

Good question...been wondering this myself.

Great answers! It helps to understand how our bodies are breaking down the fat and what it takes to burn more. *thumbsUP*

Sprinting is a great way to burn calories. I have recently added sprinting to my walking routine. I walk at 4.1-4.3 mph for 40-60 minutes depending on the day but a few times during that I sprint for a minute or two at 6.5-6.7. It really gets your heart rate up and burns lots of calories. For me that is easier than maintaining a long run.

 

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