Everyday Systems

Hi all. I know, not so busy over here, but this is a little off No S topic so I thought I'd post it here. I found this really useful website which has such a great set of ways to measure yourself - not just BMI but waist to height ratio, body fat percentage, basal metabolic rate, and your "ideal" waist measurement!

You just put in your data and it does all the calculations for you, and gives some guideline figures to help you assess your results.

Why bother? Perhaps, like me, you have a "healthy" BMI - but because of the way fat is distributed on your body ( mine is concentrated round my middle) you might actually be in the "at risk group" per waist measurement, waist to height ratio or body fat %. Well worth a look if you need this kind of motivation.

http://home.fuse.net/clymer/bmi/

The author of the site makes it available to all. Nice to find yet another person who, like Reinhard, uses the Internet for the common good.

This is really interesting, Graham - thank you. I'm amazed that my body fat %age can be measured like this!!

I agree, very interesting. I think the scientific world of weight has come a long way from the old -
if you are five foot and a woman add five pounds for every inch and you are perfect - ratio.

I am 5 foot 5 and if I get below 140, I look very gaunt so 125 would be scrawny. That is because of my body type and years of exercise.

Luckily, I don't have to worry about that right now as I am 154 today (but working on it)

Thanks again (think I might pull up this thrad and post when I am just "perfect"...

This I find interesting: none of these tools help with annoying little details like where the weight will come off.

I have this annoying metabolism that hangs on to belly fat while my face grows thin, causing friends to comment how I might be overdoing it. I don't want to have to keep removing my shirt to prove how fat I am!

These tools reassure me that I'm not crazy to be trying to lose weight, whatever my face looks like, or my BMI says. I have an "at serious risk" waist to height ratio (58%) and I fully intend to get it below 50%.

Maybe, when my weight stabilises at the new level, the subcutaneous fat might come back? Fingers crossed.

That's really interesting, Graham, thanks for posting it! A whole bucket of stats and recommendations from a variety of sources, all in one convenient place.

idon'tknow wrote:This is really interesting, Graham - thank you. I'm amazed that my body fat %age can be measured like this!!

I hate to always be a wet blanket about things like this, but ... this can only give you what the average body fat percentage would be, for someone with your measurements. That's useful information, but it's certainly not exact for you as an individual.

I assume that what the originators of that equation (on the page Graham linked) must have done is to collect a bunch of measurements of waist size and weight measurements, and then measured the body fat percentage for all those people. (Remarkably, height is *not* a factor in their equation, so if you have a 38 inch waist, it doesn't matter if you're 5 feet or 6 feet tall -- except that your weight, which does show up in the equation, will probably also be different in those case.) Whenever you do this kind of process, the best you can hope for is to get some sort of equation that gives reasonably good results across the range, but any individual data point (that is, person) could be off the average line.

Picture it like this: say they were going to relate percentage body fat to just one thing, like waist size. They'd make a graph, putting body fat on the vertical and waist size on the horizontal, and putting a point for each person: person A has a 36" waist and 18% body fat, stick that point on there; person B has a 38" waist and 24% body fat, stick that over there, and so on. By the time you've done this for a few dozen (or a few hundred) people, you'll have this cloud of points, and your job is to draw a line through that cloud that gives you the best *average* result for everybody. (I say "line", but it probably won't end up being straight.) After you draw that line, you'll be able to see that while it covers everyone, more or less, there are a lot of people whose individual points are a long way from that average line -- that's just how it goes, you can't avoid it.

So here they're doing something similar, except that they have to plot body fat percentage against two things (waist size and weight). The resulting cloud will be similarly large, and they will have done their best to reduce it to an equation as best they can ... but again, if you looked at the raw data you'd see how much individual variation there is.

I'm in the science business myself, so I always worry that people are taking this type of equation too literally -- it always looks very "official" to have an equation, but most of the time they represent pretty big assumptions, especially when dealing with something as complicated as the human body. Sorry for the unsolicited tangent into statistics and curve fitting ... occupational hazard, I'm afraid.

One last comment about this, then I'll shut up ... I just thought of what I think may be a good example of why one shouldn't trust these equations too far:

Imagine that they wanted to establish a relationship between weight and *height*. You could do it -- you can establish a relationship (an equation) relating any two things you want. You'd go out and find a bunch of people, measure each one's weight and height, and plot the weight against the height. Then you could produce an equation relating weight to height. But as we know all too well, there's a *lot* of variation in how much people weigh, when they're a particular height! The very best this equation could hope to do would be to reflect the *average* weight that people at a certain height would be expected to have. But that might have little to do with your own personal weight.

OK, I'm done now. Thanks for listening.

DaveMc, I agree with your reservations about the body fat % estimates here.

As it happens, the body fat % inaccuracy isn't too important, as there is a far more useful measure to pay attention to: the waist-to-height ratio.

Waist to Height ratio in excess of 50% is a better predictor of all the major health risks associated with excess body fat than BMI or waist measurement alone. (Based on Internet research of publications such as PubMed - Google away for the supporting research)

I don't know if I could actually wean myself off the practice of almost daily scale use (I use intermittent fasting as well as No S so there is plenty of variation to keep track of) but logically I would get more useful feedback from the regular use of a tape-measure, and they are way cheaper!

Graham wrote:As it happens, the body fat % inaccuracy isn't too important, as there is a far more useful measure to pay attention to: the waist-to-height ratio.

I like the WHR, too. It's surprising to me that a number of papers I've seen recently talk about just waist circumference: that is, the absolute number rather than the ratio of that to your height. If you have a 42" waist, surely it should make some difference if you're 5 feet tall or 7 feet ... They probably get away with it by relying on waist circumference numbers that are appropriate for the average person (again).