Body Fat and performance

Male or female, it makes a difference. I was taller and heavier than you but in line with the relative leanness. My body fat was in the same range. However, body fat measurement is not highly precise most of the time.

If you are training hard and staying at 8% for a male, that is probably fine. For females, few go below that level and it is more likely than not (i.e., at least 50%) that the measurement is below the true level, which would be just fine.

When I trained hard it was sometimes difficult to eat enough, since I did not feel like eating for a while after running and did not like to run with too much in my stomach (Bill Rogers used to get up in the middle of the night and eat a pizza to get enough in, but he was running a fair bit more than my 80-100mpw).

I am male

only a few females can run 14:39

I'd recommend you pick up a book called Racing Weight by Matt Fitzgerald. It's written for several endurance sports, but includes running and is pretty solid IMHO. As others have said, measuring body fat percentage is pretty imprecise (I've got a relatively "good" scale and it bounces between 5.1 and 9.5% for me from day to day), but the basic advice of the book is measure your weight/lean mass daily and compare with a standard performance benchmark (i.e. standard tempo workout, interval session, etc.) every few weeks...observe trends on performance and weight and determine how low is too low and how high is too high for weight/body fat.

Depending on how your body fat was measured though, I'd say you could probably stand to go a bit lower...difficult to really tell though.

I have a body fat scale that ranges from 8-9% depending on time of day. A year ago I had my body fat measured by DEXA scan and VO2 max testing. I was 117 lbs at the time (5 '8 height), running 35 miles/week and was shocked to find that my body fat percentage was 12%, given that I am so skinny and fit and had a VO2max of 74 ml O2/kg. Just from looking at myself I would have guessed a body fat percentage of more like 6-7% (ribs very visible, abs prominent etc).

TrollPatrol wrote:

I have a body fat scale that ranges from 8-9% depending on time of day. A year ago I had my body fat measured by DEXA scan and VO2 max testing. I was 117 lbs at the time (5 '8 height), running 35 miles/week and was shocked to find that my body fat percentage was 12%, given that I am so skinny and fit and had a VO2max of 74 ml O2/kg. Just from looking at myself I would have guessed a body fat percentage of more like 6-7% (ribs very visible, abs prominent etc).

you must joking right, at 5'8" 117-123lbs and a male you are probably underweight or a least at racing weight

I'm 5'9" and currently well over weight at 163lbs and 14.3% bf

think about it this way. oxygen is heavily used by fat and fat tissue. drop a pound of fat and your relative v02 max shoots up. however, i'd say 8% is relatively healthy. if you're not pro i'd get down to 5% at a minimum.

theres almost no way that 8% is an accurate measurement, or you're barely running at all. If you're male, at least.

thats a bmi of 18.7. I'm 5-8, 130, and something like 4-5% bodyfat.

Keep in mind that DEXA has an error rate around 5% and as high as 10% in some people. While you were measured at 12%, it's entirely possible that you are actually 7%.

TrollPatrol wrote:

I have a body fat scale that ranges from 8-9% depending on time of day. A year ago I had my body fat measured by DEXA scan and VO2 max testing. I was 117 lbs at the time (5 '8 height), running 35 miles/week and was shocked to find that my body fat percentage was 12%, given that I am so skinny and fit and had a VO2max of 74 ml O2/kg. Just from looking at myself I would have guessed a body fat percentage of more like 6-7% (ribs very visible, abs prominent etc).

I'm a late 20s male (never ran in HS/college).

5'7 147lbs, fat reading says 15%. Am I really overweight?

I have a pretty muscular upper body for a runner but my gf and coworkers already call me "too" skinny (size 30 jeans)

How in the world are you guys reaching the 130s or even 120s lbs at a comparable height???

kesako wrote:

I'm a late 20s male (never ran in HS/college).

5'7 147lbs, fat reading says 15%. Am I really overweight?

I have a pretty muscular upper body for a runner but my gf and coworkers already call me "too" skinny (size 30 jeans)

How in the world are you guys reaching the 130s or even 120s lbs at a comparable height???

lose a few pounds and see if you don't run better

So 8% body fat is too high or too low for a runner with a BMI of 18.7?

kesako wrote:

I'm a late 20s male (never ran in HS/college).

5'7 147lbs, fat reading says 15%. Am I really overweight?

I have a pretty muscular upper body for a runner but my gf and coworkers already call me "too" skinny (size 30 jeans)

How in the world are you guys reaching the 130s or even 120s lbs at a comparable height???

That is relatively overweight for a distance runner. Much more fat and excess weight than is ideal for 5'7

No way you're 15% BF. I'm 5'7" and 165 with a 12% BF with 32 jeans. I would say your scale is off.

TrollPatrol wrote:

kesako wrote:

I'm a late 20s male (never ran in HS/college).

5'7 147lbs, fat reading says 15%. Am I really overweight?

I have a pretty muscular upper body for a runner but my gf and coworkers already call me "too" skinny (size 30 jeans)

How in the world are you guys reaching the 130s or even 120s lbs at a comparable height???

That is relatively overweight for a distance runner. Much more fat and excess weight than is ideal for 5'7

Here are my PB over 10k:

2009 - 187 lbs - 1:05:xx (yes over 1 hour, first yr running)

2009 - 160 lbs - 0:45:xx (later that year after losing weight)

2010 - 150 lbs - 0:42:xx (about 25 mpw)

2011 - 147 lbs - 0:39:xx (just under 30 mpw)

At 187 lbs I was 28% body fat --> over 50 lbs pure fat

At 147 lbs I am 15% body fat --> about 22 lbs pure fat

I guess I could try to get into the 130s, but I would have to lose some muscle. I can't lose 17 lbs of pure fat to be 130, that'd leave 22-17 = 5 lbs of fat out of 130 = 3.8% body fat! To be that small I'd have to lose some muscle and tissue. I'm probably meant to be 140 lbs ideally.

Shertz wrote:

No way you're 15% BF. I'm 5'7" and 165 with a 12% BF with 32 jeans. I would say your scale is off.

I don't know man. I've got both a Withings scale and a Tanita scale, they read the same. Keep in mind I weigh myself about 15 mins after I wake up, before eat/drink. That yields the most conservative (but consistent) number as you are dehydrated from the night etc. If you do a measurement at midnight it is usually more flattering.

Scoreboard so far:

5'8 - 123 lbs - 8% bf [TrollPatrol]

5'9 - 163 lbs - 14% bf [runner 39]

5'8 - 130 lbs - 5% bf [no one really fast]

5'7 - 147 lbs - 15% bf [kesako] size 30

5'7 - 165 lbs - 12% bf [shertz] size 32

Body Fat Scales are notoriously incorrect. The AVERAGE error is +/- 5-6% and this becomes greater if you're outside a normal range....so if you're extremely lean or extremely fat the Body Fat Scale is no more useful than a dart board.

Unless you've been dunked (underwater weighing), used a bod pod, DEXA, or 7-site skin fold by an expert (someone who's done at least 500 readings) then your reading could be and is likely way off.

Alan

Runningart2004 wrote:

Body Fat Scales are notoriously incorrect. The AVERAGE error is +/- 5-6% and this becomes greater if you're outside a normal range....so if you're extremely lean or extremely fat the Body Fat Scale is no more useful than a dart board.

Unless you've been dunked (underwater weighing), used a bod pod, DEXA, or 7-site skin fold by an expert (someone who's done at least 500 readings) then your reading could be and is likely way off.

Alan

Thanks Alan. I'm interested in any of these tests if I could find a not too expensive way to get it done. Any link to a $100ish accurate testing site? (I live in NYC)

kesako wrote:

Shertz wrote:

No way you're 15% BF. I'm 5'7" and 165 with a 12% BF with 32 jeans. I would say your scale is off.

I don't know man. I've got both a Withings scale and a Tanita scale, they read the same. Keep in mind I weigh myself about 15 mins after I wake up, before eat/drink. That yields the most conservative (but consistent) number as you are dehydrated from the night etc. If you do a measurement at midnight it is usually more flattering.

Scoreboard so far:

5'8 - 123 lbs - 8% bf [TrollPatrol]

5'9 - 163 lbs - 14% bf [runner 39]

5'8 - 130 lbs - 5% bf [no one really fast]

5'7 - 147 lbs - 15% bf [kesako] size 30

5'7 - 165 lbs - 12% bf [shertz] size 32

mine was done in a bod pod, interesting with waist size though as I am 30" waist

runner39 wrote:

mine was done in a bod pod, interesting with waist size though as I am 30" waist

do you swim, row or do anything related to weight lifting for the upper body?