RW's formula correctly predicts marathon times based on weight loss.

Congratulations! Keep it up :)

The analysis works as long as you are over your optimal weight. However, at some point losing weight will make you slower. The trick is finding that optimal weight.

I went from being "overweight" to "normal" weight on the BMI scale, and it worked for me. I'm assuming the rule applies if you are "normal" weight or heavier. It probably does not work if you are "under weight" when you begin.

I think Meb tried to go from 125lbs to 120lbs for the 2008 Olympic Trials marathon, but I don't think it helped him. I do know of a Kenyan who lowered his weight from 140 lbs to 126 lbs, right before running his marathon PR by 3 or 4 minutes.

gregmacd wrote:

According to Runners World, you can run each mile of a marathon 2 seconds faster for each pound you lose. That roughly translates into 13 minutes faster for a 15 pound weigh loss.

In July, I ran a 3:31 at the San Fran marathon. Since then I lost 15 lbs. Thus, according to RW, I should now be able to run a 3:18, which is 13 minutes faster than my 3:31.

Low and behold, the formula works! I ran a 3:18:27 yesterday at the CIM marathon.

Now, if I can lose another 45 pounds ....

Last year, I lost 15 lbs and was then able to run the CIM Marathon in 3:18:27, which was 13 minutes faster than my previous marathon time. This matched exactly with RW's formula, which predicts a 15 lb weight loss will improve your marathon time by 13 minutes.

This year, I lost another 15 lbs, so I figured I could run CIM another 13 minutes faster for a 3:05:27 (3:18:27 - 13 min). Well, I ran CIM this year in 3:04:44! This is within 43 seconds of the RW prediction formula!

Search for this post in 2013, because I'm going to try to lose another 33 lbs. This should shave 28:36 off my 3:04:44 time for a 2:36:08, which would have won the master's division this year.

good luck on that. if you are a normal human, you can probably only lose so much weight.

I once bought a new car. Well, it wasn't new, but I just bought it, so it felt new. One door panel had been replaced, so my white car had a red door. It looked like a giant Tylenol.

As I pulled into my driveway, I saw a giant goat in the garage. I thought, "Good Grannies alive, what's that goat doing in here?" It was then that my wife stepped out of the front door and asked what was going on. I said, "There's a goat in the garage!" "A goat in the garage?" "Yeah, a goat in the garage."

Wouldn't you know it, our cat came out of the kitty door. He started going, "Meow, meow, meow!" All crazy like. Then the goat turned its attention to the cat food dish and started chowing down like a horse (well, more like a goat, really). "Meow!" Cat's still going crazy.

I thought about the situation, and decided then and there that if I ever want to PR in the marathon again, I've GOT to increase my mileage!

gregmacd wrote:

I went from being "overweight" to "normal" weight on the BMI scale, and it worked for me. I'm assuming the rule applies if you are "normal" weight or heavier. It probably does not work if you are "under weight" when you begin.

I think Meb tried to go from 125lbs to 120lbs for the 2008 Olympic Trials marathon, but I don't think it helped him. I do know of a Kenyan who lowered his weight from 140 lbs to 126 lbs, right before running his marathon PR by 3 or 4 minutes.

This is probably true. The first ten pounds lost is likely to yield more improvement than the second ten pounds. The more overweight you are, the more weight loss will help you.

I'm 5'10" and 173 lbs now, so a 33 lb weight loss would get me to 140 lbs. Not too light, and in line with the 2 lbs for every inch of height rule.

I've been averaging 70 miles a week and did 3 weeks of 100 miles this year. So its not the weight loss alone.

Hmm, so if a 150 lb runner could rip off a 2:10 marathon, if he then lost 150 lbs, he could be expected to run a 0:00 'thon, going infinitely fast, right?

Sounds like plan for Team '16 USA in Rio!

LOL! That would be nice, but I think your lower limit would be about 5-19 lbs under your inches of height * 2 lbs, which is about (1.72 to 1.92 lbs/inch). Consider the top 3 US Marathoners:

* Ryan Hall is 5'10'' and weighs 130 lbs, which puts him 10-lbs under the 2-lbs/inch rule. (1.86-lbs/inch).

* Ritz is 5'8'' and weighs 117 lbs, which puts him 19-lbs under the 2-lbs/inch rule. (1.72-lbs/inch).

* Meb is 5'5'' and weighs 125 lbs, which puts him 5-lbs under the 2-lbs/inch rule.(1.92-lbs/inch).

Time to hop on the weight vest bus.

I'm impressed that you ran 3:31 at 203 pounds. And you've been knocking out 70mpw at somewhere between 170 and 185pounds.

I've never heard about this "inches of height, times 2 lbs" thing... where did this formula come from?

I have heard of the RW "2 seconds per pound per mile" formula... that is great that your personal results were so close to the projection!

While losing the weight may have helped, don't count out the training you've been doing to get you in shape to run fast either.

wes t. wrote:

I've never heard about this "inches of height, times 2 lbs" thing... where did this formula come from?

Probably from Stillman's calculator for distance runners:

gregmacd wrote:

Low and behold

Lo and behold

max219 wrote:

While losing the weight may have helped, don't count out the training you've been doing to get you in shape to run fast either.

My mileage is only up slightly from what I was averaging over the last 6 years. With the weight loss, my pace has quickened, but my effort hasn't really increased. Thus, I figure my faster times are mostly due to weight loss.

I'm fascinated by this weight loss formula. Two years ago I shed 28 pounds in a year for a marathon, and ran 4:26:54 at age 46, 5'11.5", 180 lbs. I had nothing to compare it to, but I assumed the weight loss was very important to my result. In March '13 I have another marathon coming. My training has gone well and is very similar to last time, but I noticed I'm 15 pounds behind schedule from last time (i.e., heavier.) If I can't lose the weight, maybe I can provide data in the other direction from the poster here (i.e. in the weight-gain direction.)

I would add my opinion that weight loss helps if you're above average in weight like myself, but even at average weight I'll bet there are diminishing returns. Heading toward the weight/weight-to-height ratio of world-class runners seems less sure to be effective for us mortals.