There is a difference between fat loss and weight loss, which is what the infomercials don’t tell you.
One pound of human fat has 3,500 calories in it. Look in any nutritional science book and you will see that a 150 lb. man burns about 100 calories to run a mile. So it would require this man to run 35 miles (probably more) to burn off the equivalent of a pound of fat. I say “equivalent” because so many people assume it would be all fat. Why would it, and where does it say so? The body can also burn muscle, bone and organ tissues. As he got better at running, he would burn fewer calories, because his skill (efficiency) at running would improve.
Assuming the same conversion rate for calories consumed to usable energy (25%, according to one physics professor), a 150 lb. woman would burn the same. Remember that it’s all mechanical work: 150 lbs. moved 1 mile horizontally. You can figure it out with some info from chemistry and physics.
If we assume that this gentleman burned all fat while running, it would have taken him over a month to burn off one pound (assuming he ran one mile a day). Compare this with adding muscle to his body. Muscle uses 50-100 calories/lb./day just to keep it alive and functioning. Put on 10 lbs. and basal metabolic rate goes up 500-1000 calories/day. You could burn off 1 lb. of fat in as little as 3.5 days.
The other factor to consider is: how much potential for injury was he exposing himself to by running those 35+ miles?
High-force/overuse injuries to a multitude of body parts, not to mention the possibility of falling, compared with increasing resistance to injury through proper exercise, strengthening, enhancing flexibility, etc. Lots of running (or aerobics-type activities) will greatly reduce, stop, or reverse any improvements from strength training, due to the depletion of the resources in the human body that enable you to recover and get stronger/fitter from proper exercise.
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