effect of weight on performance

Your question is not easy to answer. Obviously it depends on what you're giving up in those 7 pounds.

If you are carrying 7 pounds of excess body fat, then I believe there is a rule of thumb that says you drop ~10 seconds per mile for every 5 pounds of EXCESS body weight lost. Hence you might drop 14 sec/mile.

If on the other hand you are not dropping EXCESS weight, but are losing beneficial muscle mass or dropping below minimal fat levels (especially females) this can have detrimental effects on current performances and result in serious long term health issues.

I don't know that we can measure or know whether the weight we are losing is excess or not, especially if we're 6' tall and weigh only 147!

Before embarking on losing 5% of your body weight, I would try to get a body fat % measurement. If your body fat is already "low", I would seriously question dropping 7 lbs.

If you are male (and I assume that you are) and your body fat is >10%, then try losing the weight slowly and see how you feel. If your training is going well and your performances deteriorate, you're probably not losing excess weight.

thanks for the advice. Yes, I am male, running at the collegiate level. I had the idea of cutting 500 calries a day from my daily intake, but tried and I get to hungry and cant do it. SO ive just been maintaining weight. 15 seconds/mile if I weight 140 though, thats some extral incentive.

Man, Im 5'10'' 150, wanting to get down to 140. I used to be a slow, but buff, 160 pounds.

Hello, Im a 5'12" collegiate runner. Im 136 right now. (didnt do xc, just starting to train again) When im not training seriously i eat lots more sweets and dont pay attention to getting the right kinds of foods. But when im in serious training (90+miles) I stop eating all the candy and stick to the veges, pasta, rice, chicken (never fried)and keep it healthy and low fat. I eat massive quantities, but without the extra thousand calories of candy (I really like the stuff) with just cutting out all the extra stuff, and good training, i drop down to 129. Im eating more than i was before, but it is all fuel with out the excess.

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5'12" comes out to 6' by the way.

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The 2secs/mile for every 1lb of fat was quoted to me too.

I lost 75lbs between May and September this year which should have given me 150secs (2.5min) per mile. My speed went from 10m/m to sub 6:30 during the same period - 3:30+ per mile difference at the same HR. I reckon retrospectively that the estimate was about right with the otehr 1min/mile being due to the training effect (0-70mpw). All my running was done 10-15bpm below LT.

What did you read Running with the Buffalos? Take a dump before you race too that helps. Shit man I'm 6'1" 170-75 and my body fat is 5% or less. The thing is you can't like these other people are saying loose muscle mass. I found out just yesterday that I'm not going to be a kenyan body runner, but I'm dealing. Plus when I play men's league hockey I still have some weight to throw around. "364 more days until next year's hockey try-out, gotta get tough" I also qualify for clysdale at the shamrock suffle and won in 2001, that's my claim to fame. 25:16