Doing the Math on Running and Weight Loss

You've seen those charts on compound interest. Was it Benjamin Franklin who called compound interest the eighth wonder of the world? I'm not sure. Some credit Einstein or others with the quote. Whoever crafted the phrase certainly had a valid point. Even a small amount of money at a fairly low interest rate, if left untouched for a long period of time, will grow into a substantial sum.

Have you ever thought of exercise calorie expenditure in the same way? Can small amounts of burned calories lead to significant weight loss? Let's explore some of the possibilities. To simplify the calculations, we will round all numbers and not get too technical in the evaluations.

So let's set 100 calories as the calorie expenditure for running 1 mile. That's probably a very conservative estimate for a number of reasons. Factoring in weight, speed, terrain and other variables would most likely increase that number considerably. There's also the likelihood of elevated metabolism following the exercise session contributing to even more calorie burning. So we are very safe using 100 calories per mile as our benchmark. Now, let's assume that you are currently a sedentary or at least fairly inactive individual in terms of regular exercise. Let's further assume that you start a running program, slowly and gradually I would hope, and you arrive at a 3 to 4 day a week schedule of 2 mile runs. Some weeks you run 4 days, other weeks only 3 days, but on average you run 7 miles a week. The math: 7 miles times 100 calories equals 700 calories/week. Here's where we see the beauty of compounding. Extend the weekly total for 1 year and you have 700 calories times 52 weeks or 36,400 calories used. It looks like a pretty big number, but what does it mean?

The approximate number of calories needed to equal 1 pound is about 3500. Theoretically, eat 3500 calories and you will gain 1 pound; burn off 3500 and you will lose 1 pound. Here's the math, then, using your yearly total: 36,400 divided by 3500 equals over 10 pounds. Everything else being equal, if you continue to eat as you currently are and devote about ½ hour to running 3 to 4 times a week, you can lose 10 pounds next year. As far as I know, there is no record of Ben Franklin running through the streets of Philadelphia. Maybe he had no need for weight loss?