Percentage of body fat or BMI?
 

Anyone here care about Body Mass Index? It simply is your weight divided by your height in inches with no allowance for whether you are a 240# weakling with the jaw as the major muscle group or a mass of bulging muscles from weight lifting. I pretty much dismissed it when I first heard about it.

I was surfing some sites this morning and come across this (very simple) calculator for %BF: http://www.he.net/~zone/prothd2.html

I realize that nothing is "one rule for all simple". That goes for everything from nutrition, to heart rate and cadence, and why we ride in the first place. I started riding years ago for weight control and it's become apparent, after a few years off, that I MUST start again, heavy duty!! :eek:

How important is overall fitness (cardiovascular and major muscle groups), nutrition and body condition image to you?

Rhumb

BMI? Nope.. Mine would be low.. I'm 147 lbs @ 5'9
Overall fitness - very.
Numbers I worry about - My aerobic gear, my heart rate when resting/aerobic/anerobic, wattage.
The rest I could care less - speed, cadence, gradient, BMI, body fat, etc...

Just ride & everything will fix itself...

Happy Riding
-Peter

To me % body fat is the best indicator of health, and I don't know why more people don't pay attention to it. I wish it would become the next "craze," but it's too logical to become a craze. BMI is fatally flawed, and it annoys me to no end when people start an exercise program and monitor their weight like crazy, only to feel like losers if they aren't losing weight. It's not about the weight- it's about how healthy you are. Why is it so hard to understand that you can actually gain a pound or two and still be healthier than you were before because you have more muscle?

I guess the only issue is that it can be hard to get an accurate measure of % BF. I don't see what's wrong with just using calipers. It's quick, relatively easy, and as long as you're consistent with your method you can use it to compare over time.

I used that formula in the past on two people - one was a man in his mid-forties, with actual body fat around 8% (measured by skin calipers). the other was in his early 20s, body fat 5.3% (again, calipers)

For the 40 y.o., the formula was only off by a little bit more than 1%. For the 20 y.o, it was off by 8% (it said his bf was 13%)

Not sure what the reason for the discrepancy was, but I tried it multiple times on both people, and got the same results each time.

Interesting Peter.

I once had a Dr. during a flight physical tell me that if I got UNDER 190#, I would be unhealthy. Playing with the %BF calculator confirms that my ideal weight at 14% to 17% is in the 198# to 205# range.

I am also 5'9"!

Rhumb

I couldn't agree more, DX.

How many fat a$$es like me have gone to the gym and started to GAIN weight because they are adding very dense muscle will dropping inches losing blubber. They get discouraged and quit because somebody put them on a scale instead of getting out the tape measure! :mad:

Gyms should outlaw scales.

Rhumb

BMI is crap... It is only useful for sedentary folks, not even for all of those. It doesn't take into account body fat (as you said) and body composition (ecto-, meso-, endo-morphic). Seems to me that someone came out first with a neat and simple formula and then tried to fit the whole population into certain ranges. The Navy method is lot better by trying to include these factors.

Based on population averages that go into BMI computation my lean weight should be around 135 lbs (given my height and weight)... But I know that my body composition is very different, my lean weight is more around 150-153 lbs... I weigh 167 lbs (height 70.5 inches), so BMI tells me (23.6) that I'm closer to the higher range (near overweight which is over 25.0), but my BF % is under recommended for males of my age (mostly between 8-11%) whereas recommended is about 12-15%... Go figure!

So to answer your original question, overall fitness (incl. nutrition) is extremely important... I see it more as a way of practicing "preventive medicine" instead of relying on symptoms (high cholesterol, overweight, heart problems, stress, etc.) to show up and treating them with drugs later on... ;)

BTW, there is a great book I read recently about how to have fun cycling and staying healthy:

Bike for Life: How to Ride to 100

My BMI has always been high!! I was a professional body builder, never fat. My body fat went from a low of 2% to what I have now, 11.76%. However, I have always been above 28! No BMI for me.

Some peop;e are confusing Body Fat and BMI>

Yeah, like most doctors I've seen. According to my BMI I should be dead, or at least hanging out with beluga whales...I was admitedly obese for a while and this year dropped some 50 pounds of lard with very little excercise (it is complicated...), Then I got back into cycling and gained back about 10-15 pounds of muscle. I'm as fit and slim now as I was twenty years ago. Yet my BMI says that I'm 20-30 pounds overweight - as does my doctor - who in the same breath asked if I had been ill because I looked so slim.

The BMI as many of you have noted, is all about averages and pays no attention to muscle mass or bone density and weight. I have big, heavy bones, but the BMI says I'm obese. Go figure. Calipers, impedence or immersion work well for measuring fat. That should be the standard. Next thing you know they will be telling us that the body doesn't need carbs.

The reason BMI is used is because it is easy. All you need is your height and a set of scales. The "normal" range of BMI is 18.5-24.9. If you're in this normal range, chances are you have a normal body fat %. It works for probably 99% of men and probably 100% of women (with the possible exception of the small minority of women on steroids). BMI is not one of those things you can use to compare one person to another and say which has more body fat. It's just an easy way to tell if someone is underweight, normal, overweight or obese. It doesn't work in all cases, but chances are if you have that much muscle mass, you probably already know to disregard BMI.

If you want to compare one person to another, a better easy way is to put a tape around their abdomen about the point of their belly button. Higher numbers generally mean more body fat. Height doesn't play that big of a factor. Women would have to measure themselves around their hips for a comparison. This method is not exact either because naturally everyone stores fat a little differently. But men store most of their fat around their abdomen, women on their hips.

I've noticed they are starting to sell scales that measure body fat %. Costco sells one for about $30. I'm not sure how it works, but I think it sends an electrical current through the body at a certain frequency and measures impedance which correlates to body fat. I doubt they are that accurate, but they might be good for reference purposes.

Hey Rhumb,
Under 190 is unhealthy? This guy was a doctor? I've never been over 180!
You must be mighty strong @ ~190lbs w/ 14% BF

Personally, health is an objective thing; if Lance was considered fit & Ulrich [cheapshot] unfit - then we'd all be waiting on our death beds.
If you feel fit, you probably are - I mean most of us on these forums DO actually bike; so I think most of us are coming around to being healthy or are already healthy enough.
If people are eating cheezies and junk all day and say they're fit because they do 10 pushups once a month - they're lying to themselves.

DX, I feel really unfit - because at my weight & BF [9%] I should be a strong rider. But I'm not. I may be "fit" medically; but I feel riculously weak on a bike - so my journey is still going.

-Peter

I used to rely on % BF as a measure of my health. I lost faith in it's reliability when I found out that ALL of the calculations are based upon age charts. It doesn't matter if you use a electronic tester, calipers or immersion tank. Your actual measurements are based upon averages in your age group. Just try one of those electronic devices and input your actual age and take the reading. Add about ten years and do it again. I guarantee it will be higher. To me that's all a crock. I want to know what MY actual percentage is based upon my own body composition, not an average for my age. Also, the electronic ones vary in their readings based upon your hydration. Thus, I just use BF as a very rough guide now to see if it's drastically changing over time.

BMI is a good basic proxy measurement for getting a rough idea if you are too fat or whether the whole population is getting too fat.
If you can be more specific like body fat %, well then use that. True body fat % is difficult to measure as some of the posters have pointed out.

The big objection to BMI that people always bring up, is that if you put on muscle, your BMI will go up. Sure thats true, but most people don't put on a lot of muscle. It depends on your genetics. I know I don't.

When we hear that the general population has an increasing BMI, does that mean that there are more professional atheletes and body builders in the population or that people are getting fatter? Which do you think?

I look at my weight, how much flab is around my middle and how easy it is for me to run up hills, to gauge the effectiveness of my fitness program. When I am doing strength training, I lose more fat than I gain in muscle so my weight and BMI go down.

Most people that tell you that they are putting on muscle and their BMI and weight are going up are full of BS. They are probably just getting fatter.

I just did that calcualtor thing, I had a Body Fat % of 13. I'm not sure if thats high or low though...

I think its average becasue my idea body weight and actual body weight are the same

BMI is worse than worthless; it's misleading. BF% is a bit better, but it's still just an approximate proxy measurement for fitness.

BMI is exactly what caloso said. The Canadian military used to use this method to determine if folks were fit or needed extra physical training. Not a true measure if someone is fit. Besides, too many high ranking weiners were busted and I think the upper echelon squashed it because of that. I've seen many "heavy" senior officers walk out of AirCommand HQ and I know they were never attending the mandatory training.

Does anyone have one of those graphs?
the ones that show the body fat and height. I dont care i just want to see where I would place.

Yeah, I like to add a couple more factors into the health equation:

- resting heart-rate
- body-fat% (lean muscle-mass)
- VO2-max
- LT-lactate-threshold
- recovery-rate


All of these combined give a more complete picture of the state of your fitness and health than any single number can.

if you want your true actual percentage i can do it for you. There is only one way.

You must put your self in a centerfuge, i'll turn it on, and we'll wait til your fat and bones and muscle are seperated. Then I'll measure how much fat you have.

Face it! The only practical way to test for body fat is through statistical analysis. These statistical tests come errors that can't be helped. The only thing to do is develop the test that minimizes these errors.
The water immersion test is the one that is most accurate; and the most impractical.

So you'll have to deal with the linear regression tests the doctors use.

Being huge mass of muscle can't be good for your heart can it? Doesn't it put a strain on your heart having to pump all that blood?

The articles that mention BMI of late have taken care to mention that if you weight train, BMI is not useful. However, if you're a cyclist with no weight trainingg, it's probably a good indicator of fat content as cyclists typically have lower total muscle mass.

Al