For me, 4 Kg = 30 sec per mile. Someone with some physics knowledge, please check my napkin math

You don't need all those silly measurements which all cancel each other out. 30 seconds / 10 minutes = 5%. 5% of 80 kg = 4 kg.

For 6:00 mile pace this will only help you 18 seconds per mile though.

Yeah, I originally did the math with a 7:00 mile (because that's about where I'm at right now) and came up with 20 seconds. So, I'm looking at a loss of 12 Kg.....

Or I can just get in better shape.

CoachB wrote:

Yeah, I originally did the math with a 7:00 mile (because that's about where I'm at right now) and came up with 20 seconds. So, I'm looking at a loss of 12 Kg.....

Or I can just get in better shape.

Not sure it works that way. I ran a 39 flat 10k and 1:26 half at 195 pounds (88 kg), and I really seriously doubt that a loss of 10 pounds would have gained me 20s per mile on either of those races. That would be like a 1:21 flat half at 185 and I cannot entertain that at all!

Oh Please wrote:

CoachB wrote:

Yeah, I originally did the math with a 7:00 mile (because that's about where I'm at right now) and came up with 20 seconds. So, I'm looking at a loss of 12 Kg.....

Or I can just get in better shape.

Not sure it works that way. I ran a 39 flat 10k and 1:26 half at 195 pounds (88 kg), and I really seriously doubt that a loss of 10 pounds would have gained me 20s per mile on either of those races. That would be like a 1:21 flat half at 185 and I cannot entertain that at all!

Well, there's a large assumption that none of the other variables change....that the only weight that is lost is non-functional fat.

39 for 10k @ 195 pounds!? Gain 5 pounds and go for Clydesdale glory!

Oh Please wrote:

CoachB wrote:

Yeah, I originally did the math with a 7:00 mile (because that's about where I'm at right now) and came up with 20 seconds. So, I'm looking at a loss of 12 Kg.....

Or I can just get in better shape.

Not sure it works that way. I ran a 39 flat 10k and 1:26 half at 195 pounds (88 kg), and I really seriously doubt that a loss of 10 pounds would have gained me 20s per mile on either of those races. That would be like a 1:21 flat half at 185 and I cannot entertain that at all!

If you're overweight (losing exclusively fat rather than muscle), it does work that way. 195 lbs is heavy.

CoachB wrote:

Oh Please wrote:

Not sure it works that way. I ran a 39 flat 10k and 1:26 half at 195 pounds (88 kg), and I really seriously doubt that a loss of 10 pounds would have gained me 20s per mile on either of those races. That would be like a 1:21 flat half at 185 and I cannot entertain that at all!

Well, there's a large assumption that none of the other variables change....that the only weight that is lost is non-functional fat.

39 for 10k @ 195 pounds!? Gain 5 pounds and go for Clydesdale glory!

Oh I did better than that, I gained 79 pounds. Yea sad to say, I did hit 274 pounds on 1/1/2020. I am down 31 now, to 243. Long way to go. Haven't run since 2016, but I do cycle still and have a half decent aerobic system still. Aiming for 165 pounds, I think I can do it. I was 155 pounds when I got out of the Army 25 years ago, so I know my "frame" is capable of it.

not very virtuous wrote:

....

If you're overweight (losing exclusively fat rather than muscle), it does work that way. 195 lbs is heavy.

Oh it was fat alright. Went through a divorce and related stress in 2012 and started gaining weight. It really started coming on in 2017 once I quit all activity. Funny thing is that at 195, I was running faster than I had been at 175, although I was training a lot more. Hitting 220 was when running became difficult, although I did run a half in something like 1:38 and this guy I finished with was amazed that I could do that "at my size"

CoachB wrote:

Oh Please wrote:

Not sure it works that way. I ran a 39 flat 10k and 1:26 half at 195 pounds (88 kg), and I really seriously doubt that a loss of 10 pounds would have gained me 20s per mile on either of those races. That would be like a 1:21 flat half at 185 and I cannot entertain that at all!

Well, there's a large assumption that none of the other variables change....that the only weight that is lost is non-functional fat.

39 for 10k @ 195 pounds!? Gain 5 pounds and go for Clydesdale glory!

Real world testing suggests the difference is more like 10-15s for most people because the other variables all change. For example now that you are lighter is your oscillation 9cm or 9.5cm given that you are hopefully applying the same force to ground and you weigh less?

For fun sometime get a 10lb weight vest and go do some intervals. Let us know what 10lbs does to your heart rate when trying to run race pace. I don't know if the OP would. have run 1:21, but I would be shocked not to see a 1:23 assuming that 10lbs is mainly fat (and unless. he is like 6'2, odds are it is fat. Odds of him walking around at 195 and. 7% BF is about zero....).

I read early on that Jack Daniel's calculates 2.7 s/mile per pound of unnecessary tissue lost, and this has been fairly spot on for me. This number scales with ability/talent level, so some may see slightly less improvement. Also, the closer to race weight you are, the less accurate this will be as you will not just be losing unnecessary tissue at that point.

I'm experimenting right now so I can come back and report

last year at 220 lbs (6"2) i ran 18:50 for 5k, 38:30 for 10km, and 1:26 for the half

trying to cut down to 200 lbs now

I have heard in the past "1 second per pound per mile" rule for every pound overweight/lost and am curious to see how this holds

Anything more than that seems like too much - but i guess it depends what kind of weight you have added

It’s a bad premise to begin with. At 197lbs I’ve ran 17:15 for 5k and 36:50 for 10k.

Just train harder and smarter.

I’m 5’10 btw

omg who cares

just train harder. I'm Male and 3yrs ago at 80/81kg I ran 17:00.8 for 5000.

You'll run quicker if you're lighter, but you'll also run quicker if you train better. if you can't run a 6:00/M then either you're new to running or your training leaves something to be desired

Oh Please wrote:

CoachB wrote:

Well, there's a large assumption that none of the other variables change....that the only weight that is lost is non-functional fat.

39 for 10k @ 195 pounds!? Gain 5 pounds and go for Clydesdale glory!

Oh I did better than that, I gained 79 pounds. Yea sad to say, I did hit 274 pounds on 1/1/2020. I am down 31 now, to 243. Long way to go. Haven't run since 2016, but I do cycle still and have a half decent aerobic system still. Aiming for 165 pounds, I think I can do it. I was 155 pounds when I got out of the Army 25 years ago, so I know my "frame" is capable of it.

Simple enough - -reenlist.

I don't know how a running watch thinks it is measuring your vertical oscillation that precisely, but the energy calculation is derived as if you were a point object, when it's really a complex thing with limbs flailing around in many different directions. Probably uses more energy thusly.

But what is the point trying to calculate how much weight loss would reach your time goal, instead of how much weigh loss you can get away with? If you're as experienced with injury as you imply, then you should know your minimum weight when you get there without even thinking. Then see how fast you go and report back and we'll have a data point better than any calculation.

JKTrower wrote:

I'm experimenting right now so I can come back and report

. . .

I have heard in the past "1 second per pound per mile" rule for every pound overweight/lost and am curious to see how this holds

The rule of thumb (credited to Tom Osler) is actually "2 seconds per pound per mile" which is more conservative than the Jack Daniels number referenced above. My recollection is that it has less to do with oscillation and more to do with increased efficiency of heart/aerobic system because there is less sludge to pump blood through,

[I have also heard it stated as 1 minute per pound over the Marathon distance. Lose 20 pounds of unnecessary fat, gain 20 minutes in a Marathon.]

Here is the the 2006 thread where jtupper (Jack Daniels) discusses this:

Here is the post:

To my knowledge 1kg of body weight = 2"50 -3" /km so 4kg of body weight is about 10"/km.

Of course we want a reduction in body fat %. mainly