Body fat and body mass questions
 

I've been checking my body fat last few months at my gym with one of those electronic testers. Body fat is usually 15 or 16 % and body mass is 22 or 23. At 15% the chart they use indicates that I'm pretty good for someone my age (60 in 3 months), but not for someone a lot younger. I don't understand why age is a factor. What's the difference if someone in their 20's has a certain % of body fat and someone in their 60's has the same %? I can understand why you have to input your height and weight into the device, but not sure why you even have to program in your age. By putting in an age, does that change the measuring process?
I also don't know what body mass is and what the scores indicate.
Can anyone help?
Thanks.
Larry

It's a largely crappy way to track one's health and fitness.

There really is no definitive way to do it, just some that are less reliable than others.

I'm more concerned about tracking my resting pulse, BP, and cholesterol; I know I'm AT LEAST as fit as many of the 25-35's I encounter (I'm sneaking up on 52), simply because I can do things they can't.

They are both a quick and dirty way of indicating the possibility of being overweight. A good body fat test, which most are not, is a better indication of being overweight than the body mass test.

BMI does not predict fat content. You could be theoretically a BMI of 40 and be considered morbidly obese and have a 6% body fat.

BMI is not a good measurement of how fat someone is. My BMI is 29 but my % body fat is 16. I could lose some weight but BMI doesn't account for muscle. For me to reach my accepted range in BMI I would have to be at my high school wrestling weight. I played football at 168 and wrestled 145. I wrestled in college at 150.

I suggest the book "Cycling Past 50" by trainer Joel Friel for explanations on aging and biking fitness. Basically, getting old sucks, but with a plan and lots of hard work, you can make it suck less.

Sorry, can't help. I have also been puzzled about how age could be a factor in body fat. And for that matter, why is gender also a factor? Seems to me that you have a certain percentage, regardless of any of these other factors.

From my understanding from something I read, but can't remember where, chicks naturally have a higher body fat % than men. Not entirely sure, but I think there are some attachments to the 19th amendment.

Yeah!!! But what about women?

Electrical test method is worthless. Calipers not much better.
Do you look fat?

Don in Austin

You really don't know why? Are you sure you're over 50?
Fat is part of the female reproductive equipment. Every girl gets fatty pads in certain areas at puberty. Ovulation stops if a woman's body fat gets below a certain level. It's nature's way of ensuring that there's enough stored energy for pregnancy and nursing. A man doesn't need as much, just enough to keep his own body going in times of famine.

I have a Taylor scale which does body fat resistance measurement and weight. It is corrected for age and athleticism.

I had a trainer at my gym do a body fat analysis using skin calipers. After he took the skin fold measurements, he added them together and referred to a chart that had columns for age. He gave my the body fat and it was sort of close to my scale. I asked him why the adjustment for age and the answer is that as one ages, there is more fat stored around organs.

My own experience with resistance measuring body fat devices is that they are very sensitive to hydration.

The most accurate is under water weighing. I had that done about 30 years ago and from time to time I see a van show up at health clubs that does an under water weighing.

In cycling the most important metric is weight - the lower the better. That does not necessarily equate to the best health. I use my pants size and look in the mirror.

Yeah, it's adjusted for the fact that as we age bone density and muscle mass decreases. With proper exercise and nutrition we can slow the process but it does happen. The figures are based on a bias of what one "should" be. Yet, there is so much variability in individuals' fitness, that the figures are often somewhat meaningless for people on either end of the continuum.

Body fat...
 

...as some here have said the numbers for one category might be good but means little if other categories are not, but as I've seen in my amateur (ham) radio club - which has middle-aged and older men who are usually sitting in front of a radio or computer for hours each day - if a person is obviously overweight and has trouble even tying their shoes, then something is very wrong and needs to be corrected very quickly, but to worry over minor changes (especially in us folks over 50 or 55) it's not worth the worry, as long as our diet is done in moderation and as cyclists are riding at least a 2 or 3 days each week, and in the case of a man he doesn't look pregnant when wearing a t-shirt (not good)...

From what I've noticed, the actual mortality rate for cyclists and non-cyclists is really about the same, but it's the "quality of life" that's the difference, since one might be a couch potato(e) while the other is outdoors enjoying the headwinds (lol)...

I'd rather be riding enjoying (a/k/a fighting) the headwinds - better for the body and mind...

We're all too fat for this sport.

As much as we hate to admit it, we all undergo a slow loss of muscle mass as we age, so, all things being equal, if our weight remains steady, our percentage body fat goes up.

It's not fair. Most of life isn't fair. I've gotten over it.

What is really puzzling is that folks in their 80's almost always undergo a dramatic loss of muscle mass, so-called sarcopenia of senescence. It happens even if they're otherwise in good health. No one knows why.

One question is when do you get to feel good about being a little chubby. It's bothered me for a long time, but now I'm learning to accept it. I chart it up to my zen thing.

Very good advice. I had a fitness instructor tell me one time, she never got on the scale - she just measured her waist, hips & thighs.

I remembered seeing something on the subject in my Physiology texts. It does not answer you question, but may provide some insight.

I've never read anything on age vs percentage of body fat vs mortality that had any credibility. However what I have read is that resistance measurements are not very accurate. The caliper/skin fold measurements are pretty good if done by an expert. Also, we worry way to much about body fat.

I did find a statement in Sport Nutrition for health and performance (2nd edition, pub 2009) which I'll paraphrase:

Proposed body composition standards include some increase in %BF with age rather than imposing the current young adult standard. It goes on to state that a young adult with 24% BF would be encouraged to lose some while a middle aged man would be in the healthy range.

There's also the statement that a lower level of fat body in middle age is associated with lower bone mineral content and an increased risk of bone fracture. IMO, that's probably more for the sedentary, though road cyclists tend to have poorer bone health than say joggers or even pro mountain bikers.

I'll cite some mortality statistics from just one of the studies on activity vs fat reported in Physical Activity and Health, the Evidence Explained (second edition, pub 2009)

The data is from a study of 22,000 men aged 30 to 83. Fitness was measured using time to exhaustion on a treadmill test. Body fatness was assigned as lean (less than 16.7% body fat), normal (16.7 to less than 25%) and obese (greater than 25%).

Fat was measured by hydrostatic weighing, skin fold thickness or both. Average follow-up was 8 years. They adjusted for age, smoking, family history of heart disease and alcohol consumption.

Results: lean unfit men had twice the all-cause mortality of obese fit men.

There are several other studies reported with the same kind of results. Fat is not the issue, physical activity is. That said, obesity is not a good idea, but neither is thin.

You find this stuff in the popular media or from the government.

Al

Thanks for all the information and feedback.
Larry

Because when you get older you make less of many hormones, including testosterone. You make more of others like estrogen. Testosterone and estrogen regulate body composition (among other more obvious things). While an athlete can train hard and eat right to lose weight, and will lose fat (compared to a sedentary person), how low they can go is determined in part by their hormones.
Because that's how it works. Women have more body fat (on average) than men. Presumeably that's because they need additional resources for producing children... women who didn't start out a pregancy with enough body fat to support a child didn't reproduce successfully and thus the genes for low female body fat did not get passed on. Or it may be because god likes curvy women.

I had a serious error in my long post.

I should have written:

Results: lean unfit men had twice the all-cause mortality of obese fit men.

I had left out the word "fit" .

Al

I think you misunderstood me. I am not questioning that women tend to have a higher percentage of bodyfat. I am questioning why it is a factor in measuring bodyfat.

So I get that people loose muscle mass as they age and I get that there is a difference between men and women, but if you are measuring body fat, it seems any device that claims to be capable should simply report bodyfat percentage and wouldn't need to know about age or gender.

Thanks for your condescending reply to my post, by the way.

You are not answering my questions either. See my previous post.

Well, as pointed out above, women have significantly more in percent body fat than men.

I have heard of people talking about folks with 0 percent body fat. Can't be done. Cell membranes are made up of phospholipids or fats. Nervous tissue is largely lipids. Without some fat, your tissues would be like jello and you wouldn't have any brains.

Men are pretty much at their minimum % body fat at 5% which is about what body builders shoot for when they compete. The less fat they have, the better their muscles show up. The muscles are not obscured by a thin layer of fat under the skin. Men are pretty lean at 10% body fat. With men, anything at or under 15% is fine.

Women seem to hit their minimum body fat at 10%. Anything under 15% usually shuts down their reproductive system. Any woman who is under 20% body fat is doing just fine. Women need to have at least a certain amount of calories to go through a pregnancy successfully. So a bit of fat means a greater fertility. Maybe Rudens with his plump nudes was onto something.

There are various ways to estimate body fat but none of them is accurate. The hydrostatic test is generally touted as the gold standard. But I knew a woman who started cycling, lost 10 lbs (she was not at all plump), put on muscle and did a before and after hydrostatic test. She supposedly increased % body fat. I figured that the aerobic fitness had increased her lung capacity which would have been interpreted as increased fat in the test. I think a caliper test works just fine for caparative purposes. Shoot even an informal skin fold pinch between your navel and crown of the pelvis works fine for the "am I losing fat" question. To really get the right number, you have to measure the fat. The best way is to take the person, throw them into a blender and skim off the fat and weigh it. But that is a bit drastic and you don't get too many people who opt to use it.


As people age, they tend to lose about 1% of the aerobic capacty and 1% of their muscle mass per year. People also tend to get a slower metabolic rate as they age. People also tend to gain weight as they age. So they get heavier but have less muscle which means their percent body fat tends to go way up. The good news is that regular aerobic activity and some weight training can almost halt the loss. Also even people who are advanced middle aged (which is a nice way of saying "old") can with exercise regain quite a bit of what they lost.

Turns out it has to do with osteoporosis in older subjects.

Measuring bodyfat in a water tank requires weighing a person outside the tank, and immersing them in water and weighing them again. The densities of bone and muscle are higher than water, and fat is less dense than water. In other words, fat floats. So supposedly the difference in weight is accounted for as bodyfat.

But this method assumes that densities of nonfat mass, like bones, are constant. However, athletes tend to have denser bones and muscles than non-athletes, which may lead to an underestimation of body fat percentage. On the other hand the body fat of elderly patients suffering from osteoporosis may be overestimated.

So I guess this explains why the Omron device I have at home wants to know your age -- it must make some kind of adjustment when it calculates bodyfat percentage relative to bone mass.

Still doesn't completely explain why you'd input gender, unless they assume a higher rate of osteoporosis in females. But that's just a guess.

No one understood what you were asking in your first post. If you want your questions answered you need to make it clear what you are asking.


To answer your other post, the impedance scales don't measure body fat directly. They estimate it based on the body's electrical resistance. It's basically a table lookup from data correlating body fat (hopefully measured accurately) to resistance. But since there's not a direct correlation, they need inputs like sex and age.

Body fat calipers also need to be adjusted for sex and age because men and women store different amounts of body fat internally, where the calipers can't measure. And the same happens as we age. Hydrostatic (dunk tank) doesn't have that problem. But it's not as conveient as the others.

here's good link on body fat calipers:

http://www.sport-fitness-advisor.com...tcalipers.html