Lose 5 lbs. = shave 2:30 off your 10K time?

Well, my question would be this:

 What brought about the speed, the lost weight, or the training that it took to lose the weight?

I'm willing to bet that if the 5 lbs was lost by increasing training load, said weight loss was secondary. 

Go lose 5 pounds and let us know. 

If it is true then I should be running alot faster by now.  I started at 240lbs a year ago and am now 199lbs.

I started at 12 min miles a year ago and did a 9:59per mile 10k in Feb and a 9:09per mile 5k 2 weeks ago. 

Let's see, 12 min miles and 40lbs lost. 

He said 25 seconds for every mile for every 5 lbs.  40lbs / 5lbs = 8.   8 times 25 secs = 3min 33 seconds saved.

My 5k should have been 12min miles minus 3min 33sec = 8:27 min per mile and that is assuming no training according to the statement.

Personally, going through alot of weight loss, I definately notice a difference but it is a combination of training and weight loss and I think the training is a larger % but they can't be separated. 

running2far - 2008-07-14 9:20 AM

bradword - 2008-07-14 9:19 AM The key is, if you lose 5 pounds AND MAINTAIN THE SAME WATTS! If your watts go down with the weight it doesn't apply. If you push 250 watts at 200lbs and 250 watts at 195lbs, it applies.

I'm pretty sure they don't let you ride a bike in a 10K

I do a 10K time trial (yes, that's on the bike) in competition twice a year.

Unfortunately, you can lose muscle weight even if you aren't skinny (i.e., low body fat).  Alas, if you train and eat improperly, your body doesn't forgive you -- it doesn't know that you want to lose the fat rather than the muscle.

In fact, I'd speculate (but this is pure speculation) that somebody who is skinny (let's say < 9% body fat for a male) is LESS likely to have the problem of losing muscle weight, on the theory that such a person got skinny in the first place by properly training his body to burn fat.