Why I hate Body Fat Percentage!

vismal

We'll start with bio electrical impedance devices. Those scale you step on, or the handheld device you grab. These are basically trash.

That's silly! Here's a graph of my body fat % trending down 7% over the past six months--



Studies and reviews generally find BIA scales as being +/- 3% accurate. Thus, if my number is 25%, I may really have 22% body fat or 28% body fat. While that's a wide range, those same studies/reviews generally find BIA scales to be consistent. Thus, my trend of -7% is actually indicative of serious progress!

Unless you are at exactly the same level of hydration each and every time you use the machine, they will not be accurate for you.

That's why--as with weight--you measure at a consistent time each day, typically first thing in the morning after peeing. With the exception of unusual events--periods, sodium spikes, alcohol binges, endurance workouts, etc.--you get fairly consistent measurements from day to day.

There is no way to tell if your hydration level is the exact same as it was last month

Exactly? Nope. So, I ignore tiny changes (the +/- 0.2% this week) and focus on trends (the -7% in 6mo.)

so I place these devices near the bottom as far as accuracy is concerned.

Georgia State University--who tested to determine the accuracy of each method--disagrees with you and puts BIA and Skinfold Caliper tests at about the same accuracy level. More important, they provide tips you can use to increase the accurayc of both types of measurements.

http://www2.gsu.edu/~wwwfit/bodycomp.html

Of course, if high accuracy is critical, pay for a Dexa or Bodpod.

But my entire point was at what point would high accuracy ever be critical? At what point is knowing that number going to change anything? I bet you knew your body fat was decreasing despite that graph. Also, Georgia said that calipers and BIA were +/- 3% compared to underwater weighing which they said also has a +/- of 1.5! This is also directly from the article on how one needs to prepare for BIA testing. I'm wondering how often people are actually compliant with all these things.

Abstain from eating and drinking within 4 hours of the test
Avoid exercising within 12 hours of the test
Void (urinate) completely prior to testing
Do not drink alcohol within 48 hours of the test
Avoid taking diuretics prior to testing unless instructed by your physician

There reading on accuracy were based under perfect conditions. I question whether the guy making 10 bucks an hour at planet fitness is going to help create a "perfect condition".

canadjineh

Thank you CA Underdog... great link.

nyboer

Bump to read later.

Aaron_K123

An untrained male can gain about 26 lbs of lean mass in his first year of training if he is eating in a SURPLUS.

Holy crap should I be so lucky, I was thinking it was more like 10 lbs not 26.

vismal

An untrained male can gain about 26 lbs of lean mass in his first year of training if he is eating in a SURPLUS.

Holy crap should I be so lucky, I was thinking it was more like 10 lbs not 26.

That number comes from this article: http://www.bodyrecomposition.com/muscle-gain/whats-my-genetic-muscular-potential.html

jim180155

Using scale weight has all the possible inaccuracies and outside factors that can throw it off that goes with monitoring body fat.

However if you weigh the same way every time, then over time you can get an idea of your general weight even though it will not be exact.

What's wrong with doing the same thing with body fat percentage?

I would trade out your number 4: Scale weight with Body Fat %.

Just tracking with my scale my weight went down 1 lb but my body fat went down 4 %. I also was tracking with photos, clothing size, and measurements. But I get much more excited about losing body fat than I do about weight.

Scale weight is only inaccurate if your scale is broken. Yes scale weight can be skewed by water retention but it should be going down over time. You can weigh yourself daily for free so you can have several data points to plot. The more accurate ways to measure body fat aren't usually something you can do daily, or even weekly. So it takes a long time to get enough data points to start getting a trend. This is why I put it at the bottom of the list as far as importance. You progress pictures are excellent at proving me point, looking at those do you need a machine to tell you that you've lost fat? Of course you don't it's evident to anyone that you have! Congrats on that by the way

Although I agree with a lot of what you said, Vismal, I don't think you're being consistent here. The electronic scales you called "trash" are relatively cheap, just like other scales, and once purchased, readings can be taken as often as one wishes, with no additional costs. So you can have as many data points as you like, just like you can with weight readings.

I weigh myself every morning. I log my weight and body fat%, along with several other readings like skeletal muscle % and visceral fat. I also calculate the number of fat pounds (weight * BF%) and skeletal muscle pounds (weight * SM%). The overall numbers might be off, but within the framework that I'm using, they are fairly consistent. Most days my BF% and SM% vary by less than one percent. There are days where I see a jump of close to 2% points, but those days are rare. What I am NOT seeing is swings of 10%: up 5% one day, then down 5% the next.

I'd need a DEXA scan to really know my BF%, but I'm not overly concerned with the number, so I haven't had it checked. What I do know is that my BF% has trended down in the last 6 months from 22% to 14% (or less than 13% on a "good" day). I might not be at 14%. I'd guess I'm closer to 20% than to 10%. But it's the trend that's important to me. I like seeing progress, and I like to measure it as many different ways as I can, provided that there is some objectivity to the measurements.

DrJenO

It's no different than tracking your weight with a scale. Sure, you can look in the mirror and tell you look better, but some people like numbers. I'm one of them, as is CA_Underdog, I suspect.

The problem is that when you let the numbers define you and your self-worth, you've lost sight of the bigger picture. I suspect your bigger issue is with people that get so caught up in the actual number that they lose sight of the forest for the trees.

albayin

Wonderful info! Well written!

I will ask the burning question though....

How do you recommend tracking progress?

Good question! I track through multiple ways. I will list all the things I track starting with what I value the most to the least

1: Progress pictures/ the mirror. (These simply do not lie, you either look better or you don't!)
2. The way my clothes fit
3. Tape measurements
4. Scale weight

If 3 out of 4 of those things indicate progress is being made, I can be fairly sure that progress is being made!

None of above changes in a noticeable way, does that mean I am such a loser with no progress? crying my heart out...:brokenheart:

Aaron_K123

First let me say I agree Vismal that most methods of bodyfat measurement that people have access to have a high percentage error associated with them. That said with anything that has a standard deviation error associated with it the more measurements you take the more that error will smooth out and you can still get very good trend data from regular bodyfat measures.

I use both tape measurer and bodyfat calipers personally. I fully understand that each individual measure is going to be inaccurate but with regular measurements over time and the ability to smooth the error with averages you can still get good data out of it.

albayin

Actually pictures/mirros do lie...if you stand in different lighting or angle, holding camera slight different you will look different.

Also if you were dehydrated or bloated from previous night over eating, your picture looks different too. So now I just crushed your #1 tracking method.

Francl27

Actually pictures/mirros do lie...if you stand in different lighting or angle, holding camera slight different you will look different.

Also if you were dehydrated or bloated from previous night over eating, your picture looks different too. So now I just crushed your #1 tracking method.

True!

vismal

Actually pictures/mirros do lie...if you stand in different lighting or angle, holding camera slight different you will look different.

Also if you were dehydrated or bloated from previous night over eating, your picture looks different too. So now I just crushed your #1 tracking method.

Which is why I take them in the same room under the same light, the same distance from the mirror. Bloating and dehydration are hardly enough mask my progress over the course of 2 months.

Aaron_K123

It's no different than tracking your weight with a scale. Sure, you can look in the mirror and tell you look better, but some people like numbers. I'm one of them, as is CA_Underdog, I suspect.

The problem is that when you let the numbers define you and your self-worth, you've lost sight of the bigger picture. I suspect your bigger issue is with people that get so caught up in the actual number that they lose sight of the forest for the trees.

Honestly when people who let their appearance define their self-worth get high and mighty over people who let their scales define their self-worth it just makes me smirk a bit.

I think the idea is that both want to look good and one is using looking good as a measure while another is using a much more arbitrary number as their measure. I get the idea you should go off appearence over a scale weight but honestly both are pretty shallow means of judging self-worth.

vismal

It's no different than tracking your weight with a scale. Sure, you can look in the mirror and tell you look better, but some people like numbers. I'm one of them, as is CA_Underdog, I suspect.

The problem is that when you let the numbers define you and your self-worth, you've lost sight of the bigger picture. I suspect your bigger issue is with people that get so caught up in the actual number that they lose sight of the forest for the trees.

Honestly when people who let their appearance define their self-worth get high and mighty over people who let their scales define their self-worth it just makes me smirk a bit.

I think the idea is that both want to look good and one is using looking good as a measure while another is using a much more arbitrary number as their measure. I get the idea you should go off appearence over a scale weight but honestly both are pretty shallow means of judging self-worth.

OMG SO TRUE! None of this stuff should determine your self worth!

Aaron_K123

I hear people saying: No no, don't use scale weight use bodyfat percentage! Or no, no don't use body fat percentage use appearance. Or no no don't use appearance use tape measure.

I'm just sitting here thinking to myself...why not just use all of them. Its not like you have to pick one. More data the better right?

Aaron_K123

It's no different than tracking your weight with a scale. Sure, you can look in the mirror and tell you look better, but some people like numbers. I'm one of them, as is CA_Underdog, I suspect.

The problem is that when you let the numbers define you and your self-worth, you've lost sight of the bigger picture. I suspect your bigger issue is with people that get so caught up in the actual number that they lose sight of the forest for the trees.

Honestly when people who let their appearance define their self-worth get high and mighty over people who let their scales define their self-worth it just makes me smirk a bit.

I think the idea is that both want to look good and one is using looking good as a measure while another is using a much more arbitrary number as their measure. I get the idea you should go off appearence over a scale weight but honestly both are pretty shallow means of judging self-worth.

OMG SO TRUE! None of this stuff should determine your self worth!

Just because I want to be healthier and look my best doesn't mean I derive my value or my confidence from my appearance. The fact that I couldn't really give two sh*ts most days is why I get into the need to lose weight in the first place ;-)

DrJenO

I hear people saying: No no, don't use scale weight use bodyfat percentage! Or no, no don't use body fat percentage use appearance. Or no no don't use appearance use tape measure.

I'm just sitting here thinking to myself...why not just use all of them. Its not like you have to pick one. More data the better right?

This is really all I meant. We are all using all of these things. And none of them.

I don't think picking this one data point as completely worthless is any more valid than saying weighing yourself, or measuring yourself, or looking in the mirror, is invalid.

As long as you accept the facts (BF measurements carry a margin of error), track away.

albayin

It's no different than tracking your weight with a scale. Sure, you can look in the mirror and tell you look better, but some people like numbers. I'm one of them, as is CA_Underdog, I suspect.

The problem is that when you let the numbers define you and your self-worth, you've lost sight of the bigger picture. I suspect your bigger issue is with people that get so caught up in the actual number that they lose sight of the forest for the trees.

Honestly when people who let their appearance define their self-worth get high and mighty over people who let their scales define their self-worth it just makes me smirk a bit.

I think the idea is that both want to look good and one is using looking good as a measure while another is using a much more arbitrary number as their measure. I get the idea you should go off appearence over a scale weight but honestly both are pretty shallow means of judging self-worth.

OMG SO TRUE! None of this stuff should determine your self worth!

Just because I want to be healthier and look my best doesn't mean I derive my value or my confidence from my appearance. The fact that I couldn't really give two sh*ts most days is why I get into the need to lose weight in the first place ;-)

I have been lucky with my health until I started to torture myself trying to lsoe weight. Now I am weak and depressed...I think I got the whole thing backward...

usmcmp

I hear people saying: No no, don't use scale weight use bodyfat percentage! Or no, no don't use body fat percentage use appearance. Or no no don't use appearance use tape measure.

I'm just sitting here thinking to myself...why not just use all of them. Its not like you have to pick one. More data the better right?

This is what I was saying. Why not track weight, body fat, measurements, etc. Even blood work, lifting stats and mile run times are good things to track. They are all indicators of progress. Plus, with body composition it is better to have lots of data.

Aaron_K123

I hear people saying: No no, don't use scale weight use bodyfat percentage! Or no, no don't use body fat percentage use appearance. Or no no don't use appearance use tape measure.

I'm just sitting here thinking to myself...why not just use all of them. Its not like you have to pick one. More data the better right?

This is what I was saying. Why not track weight, body fat, measurements, etc. Even blood work, lifting stats and mile run times are good things to track. They are all indicators of progress. Plus, with body composition it is better to have lots of data.

I think what Vismal is saying (and he can correct me if I am wrong) is not so much omg don't do this its a waste of time so much as he is saying that too many people become myopically focused on achieving the magic number of 10% or 18% and ignore other factors that are arguably more important like...how much energy do they have....how strong are they feeling....how far can they run....what is their functional strength....how do they look.

That said I think its perfectly fine to measure bodyfat percentage and have a goal in mind, just as long as you are rational enough to realize that measurements aren't 100% accurate and your goal might end up needing to shift as you learn more about your own body.