Questions about body fat and frame

Aviva92

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3066051/
Shows people with BMI's higher than 25 have a higher risk of death, regardless of body fat percentage. Meta analysis performed on 19 long term studies, with 1.5 million subjects.

hmmm, i didn't read that whole thing because it's long and boring, but it seems to say that people who are on the low end of normal with a BMI of 18.5-19.9 have a higher mortality rate at 1.14% compared to overweight people at 25-29.9 having a mortality rate of 1.13%. What am I missing? Is being overweight better than being on the low end of normal?

tigersword

They addressed that, basically that needs more study, but from the data they had, it appeared that the mortality rate on the lower end of the BMI may have been affected by preexisting diseases that caused the low weight in the first place, as ther majority of the low weight deaths occurred within 5 years.

victoria4321

As for the "obesity paradox," here's an abstract of a review that puts forth the hypothesis that the paradox is more a cause of medical advances than any specific protective ability of obesity.
http://www.ncbi.nlm.nih.gov/pubmed/23017304

My question then would have to be why dont the lower weight people get the same benefit from the advances in medicine?

BinaryPulsar

1.14% and 1.13% is such a small difference. Isn't that considered statistically insignificant? Especially when compared with all the other data that pushes it in the other direction (plus the point about the people that are at a low weight due to a pre-existing illness).

Azdak

Someone can be 110lbs and be 30% bodyfat. Its common when someone does a lot of cardio and no resistance training.

Oddly enough, I have done thousands of body composition assessments over almost 30 years. I have seen every frame size imaginable. While I have not worked with many people who have suffered from eating disorders, I have worked with plenty of folks who have followed all manner of "diet" plans, including gastric bypass surgeries. I have NEVER, ever seen someone who had an overly high body fat % due to their ratio of cardio to resistance training. I have seen a number of men and women who would be considered "skinny fat"-- who had an unexpectedly high BF% based on their scale weight and appearance (e.g. a 5'4" woman who weighed 110lbs and had 28% body fat).

In most cases, the measurements were due to the individual's genetic body type. Most were measured at the beginning of their exercise program and few, if only, had ever dieted. The primary exceptions were those who were recovering from a serious injury, illness, cancer treatment, etc.

And while not rare, they are not "common" by any means. This is one of those cliches that's gets thrown around a lot these days, but, like many cliches, however, it doesn't really stand up to scrutiny.

Aviva92

Another thing to keep in mind with these scales is that they depend upon a person having ideal hydration and not being used immediately after a workout and consistently used under similar conditions. A lot of people don't use them as instructed...so even the best electronic impedance device can read way off.

I haven't noticed much of a difference whether or not I'm hydrated. Consumer Reports does not rate body fat % scales because they state that none of them are accurate.

Aviva92

Someone can be 110lbs and be 30% bodyfat. Its common when someone does a lot of cardio and no resistance training.

Oddly enough, I have done thousands of body composition assessments over almost 30 years. I have seen every frame size imaginable. While I have not worked with many people who have suffered from eating disorders, I have worked with plenty of folks who have followed all manner of "diet" plans, including gastric bypass surgeries. I have NEVER, ever seen someone who had an overly high body fat % due to their ratio of cardio to resistance training. I have seen a number of men and women who would be considered "skinny fat"-- who had an unexpectedly high BF% based on their scale weight and appearance (e.g. a 5'4" woman who weighed 110lbs and had 28% body fat).

In most cases, the measurements were due to the individual's genetic body type. Most were measured at the beginning of their exercise program and few, if only, had ever dieted. The primary exceptions were those who were recovering from a serious injury, illness, cancer treatment, etc.

And while not rare, they are not "common" by any means. This is one of those cliches that's gets thrown around a lot these days, but, like many cliches, however, it doesn't really stand up to scrutiny.

I believe this. Some people are just naturally muscular and others are not. I know one woman who has never worked out a day in her life and she has a 6 pack.

I always though that losing muscle due to dieting was mostly a myth. It wasn't as though gaining weight put on any muscle to begin with.

tigersword

1.14% and 1.13% is such a small difference. Isn't that considered statistically insignificant? Especially when compared with all the other data that pushes it in the other direction (plus the point about the people that are at a low weight due to a pre-existing illness).

I would agree that 1.14 and 1.13 would be statistically insignificant, but that's not what the researchers were comparing. They were comparing mortality rates between BMI ranges and what they found were that people with BMIs between 18.5 and 19.9 had a higher mortality rate than people with BMIs between 20 and 24.9 (1.14 vs 1.00.) They weren't comparing BMIs from the low end of the range with overweight, specifically. That was just Victoria pointing out an interesting statistic. Another interesting statistic is that people with underweight BMIs (under 18.5) had almost the same mortality rate as people with a BMI between 30-34.9 (1.47 vs 1.44.)

Aviva92

1.14% and 1.13% is such a small difference. Isn't that considered statistically insignificant? Especially when compared with all the other data that pushes it in the other direction (plus the point about the people that are at a low weight due to a pre-existing illness).

I would agree that 1.14 and 1.13 would be statistically insignificant, but that's not what the researchers were comparing. They were comparing mortality rates between BMI ranges and what they found were that people with BMIs between 18.5 and 19.9 had a higher mortality rate than people with BMIs between 20 and 24.9 (1.14 vs 1.00.) They weren't comparing BMIs from the low end of the range with overweight, specifically. That was just Victoria pointing out an interesting statistic. Another interesting statistic is that people with underweight BMIs (under 18.5) had almost the same mortality rate as people with a BMI between 30-34.9 (1.47 vs 1.44.)

In looking at that study it shows the mortality rate for 18.5 through 19.9 and then 20 through 22.4. Then it skips to 25 to 29.9. Where is 22.4 through 24.9? Or is that a typo and 22.4 should say 24.9?

Ejourneys

I use this (in addition to my scale, tape measure, and mirror):
http://www.accumeasurefitness.com/

tigersword

1.14% and 1.13% is such a small difference. Isn't that considered statistically insignificant? Especially when compared with all the other data that pushes it in the other direction (plus the point about the people that are at a low weight due to a pre-existing illness).

I would agree that 1.14 and 1.13 would be statistically insignificant, but that's not what the researchers were comparing. They were comparing mortality rates between BMI ranges and what they found were that people with BMIs between 18.5 and 19.9 had a higher mortality rate than people with BMIs between 20 and 24.9 (1.14 vs 1.00.) They weren't comparing BMIs from the low end of the range with overweight, specifically. That was just Victoria pointing out an interesting statistic. Another interesting statistic is that people with underweight BMIs (under 18.5) had almost the same mortality rate as people with a BMI between 30-34.9 (1.47 vs 1.44.)

In looking at that study it shows the mortality rate for 18.5 through 19.9 and then 20 through 22.4. Then it skips to 25 to 29.9. Where is 22.4 through 24.9? Or is that a typo and 22.4 should say 24.9?

22.5-24.9 was their reference category. They used that to determine their baseline mortality. It just happened to turn out that 20-22.4 had the same mortality rate, hence the ratio of 1.00 (baseline.)

RhineDHP

I haven't read too many of the other comments, but I have read some of yours, and I guess I could throw in my two cents.


There's a good chance that scale is mostly right. Why? Because at 5'0 you're 125 pounds. I'm 5'1, and 126-7 pounds at the moment. I checked my BMI a long time ago, when I was....maybe 118, and it told me mine was 28%. I too have tig ol bitties (haha, 34DD), and I know I have more fat than muscle at this point.

Bravo on fitting into a size 2 btw, I think on a good day only one skirt from a certain store that's now gone I can fit into it...mayybe.


But hey, I could be wrong and the BMI given to me back then was inaccurate. I'll say this, you're definitely a lot more active than I am. Maybe that's all 125 pounds of muscle. And boob.

RobynLB

Body fat percentage has nothing to do with your height. It's a percentage, so that's already taken into account. Also, women are already given a higher healthy body fat percentage to allow for breasts (and other womanly fat deposits) so that's already taken into account. If you're on the borderline of over fat... it is what it is... you aren't being betrayed by some system that doesn't take into account your frame, gender, and height.

Those scales are pretty worthless though. Someone suggested using the athlete setting, but the athlete setting is not for light exercisers, it is for people who do intense training for 10+ hours a week. Intense training does not mean Zumba.