As many of us following the BFL program are using a percentage of body fat as a goal I thought some information on just what comprises this number relevant. What follows is information I have pieced together while researching the subject. At the end of the post I have attached two charts which provide information on BF% goal for men and women at various ages.

[the following is copied from Elizabeth Quinn M.S. article Body Composition Basics at about.com's Sports Medicine site .. and from The Important Role of Body Fat Percentage from how-to-gain-weight.com]

Body Composition

Body Composition is the technical term used to describe the different components that make up a person's body weight. Now you must keep in mind that body composition and body weight are two entirely different concepts, and they are not interchangeable. To get a better understanding of the difference between the two, you need to understand a bit about anatomy and physiology.

Body Tissues

You probably realize that the human body is composed of a variety of different tissue types. The so-called 'lean' tissues, such as muscle, bone, and organs are metabolically active, while adipose, or fat tissue, is not. The difference in these tissues is not readily distinguishable by stepping on a scale. A scale simply takes the sum of everything (fat, muscle, water, hair, you name it), and gives an absolute weight measurement. Scales can't determine the lean-to-fat ratio of that weight. An individual can be "over-weight" and not "over-fat." A bodybuilder, for example, may be 8% body fat, yet at two hundred and fifty pounds may be considered "over-weight" by a typical height-weight chart. Therefore, these charts are not a good indication of a person's ideal body weight for optimal health, much less for athletic performance.

In order to identify these tissues, physiologists have developed several different methods of assessing the percent of fat vs. lean mass of an individual. These methods are referred to as Body Composition Analysis. There are many methods of assessment.

The gold standard of body composition analysis is hydrostatic or hydrodensitometry. Although, because it is time consuming, cumbersome, and complicated, and difficult to find, many physiologists turn to other types of measurement as an alternative means of assessment. However, hydrostatic weighing is the method by which all other means of measurement compare their degree of error.

What should your body fat percent be?

Well, this is a loaded question, and the answer reflects the controversy surrounding the issue. A better question might be, "What is your ideal weight? Body fat percent varies considerably for men and women, for age and culture for those involved in different sports activities, and even for different geographic location. However, there are some 'standards.' The minimum percent body fat considered safe and acceptable for good health is 5% for males and 12% for females. The average adult bodyfat is closer to 15%-18% for men and 22%-25% for women.

Athletes, typically, find themselves at the low end of this scale. Optimal levels of body fat are much lower for those striving for high level performance. Ranges for professional athletes are quite a bit lower than for the average, healthy individual. Much of this difference can be attributed to the increased lean weight (muscle mass) of top athletes. The impact of body size on performance is one consideration that may correlate with body fat.

While levels of body fat seem to be related to performance, body composition alone has never been a great predictor of sports performance. Several studies have suggested that percent body fat is inversely related to maximal aerobic capacity and to distance running performance. Lean muscle mass seems to be positively related to performance in sports where the ability to generate maximal force is required (this may help to explain why a lot of those defensive linemen appear to have a high body fat levels). The body fat percents for elite athletes vary largely by sport. Clearly, the association between low body fat and improved performance is not precise, and there is little evidence of performance benefits when male athletes drop under 8% and women drop under 14% bodyfat.

How Low Is Too Low?

Athletes can take this "low body fat in the name of improved performance" idea too far. While the average body fat percent in the United States and Europe is increasing, low body fat percent is clearly a health problem. The female athlete triad of disordered eating, amenorrhea, and osteoporosis is a relatively new phenomenon. Women athletes who strive for better performance and lower body weight, often find themselves caught in a negative spiral that actually leads to decreased performance and health risks. Eating disorders require special attention and professional assistance. There have even been steps taken by the National Collegiate Athletic Association to keep wrestlers from going too far when it comes to 'making weight', or reducing their weight to qualify for a lower wrestling weight class.

How Much Is Too Much?

Just as too little body fat can create some pretty devastating physiological complications, too much body fat can have equally harmful effects. Once men creep up over 25% and women over 32% fat, there is a dramatic correlation with illness and disease. In fact, body composition has been used more and more to make future predictions about health and disease in individuals.

Health Risks Associated With Too Much Body Fat Include The Following:

• • increased blood pressure
  • increased total cholesterol level
  • increased LDL (bad) cholesterol
  • increased risk of cardiac problems
  • increased risk of Diabetes
  • hardening of the arteries
  • aggravation of osteoarthritis
  • promotes blood clots and varicose veins
  • GI disorders
  • increased predisposition to some cancers
  • decreased reaction time
  • reduced balance and coordination
  • increased susceptibility to infections
  • decreased circulation
  • delayed wound healing

Lower is Not Necessarily Better

A certain amount of body fat is vital for the body to function normally and healthily. In fact striving for a body fat percentage that is too low can be dangerous. Here's why:

Measuring your body fat percentage calculates your TOTAL body fat. This total body fat can be split into 2 categories.

Storage Fat -- This consists mainly of fat deposited just under the skin or subcutaneous fat. Storage fat for men and women is fairly similar. For the average man 12% of bodyweight is storage fat and for the average woman 15% of bodyweight is storage fat.

Essential Body Fat -- For the body to function normally and healthily a certain amount of body fat is required. This is called essential fat. For women the average amount of essential fat is 12% of bodyweight and for men it is 3%.

Trying to achieve a body fat percentage that is so low it effects your essential fat stores is NOT good for your health. Some storage fat is also required for good health. Why? It is used to protect internal organs in the chest and abdomen. So aim to stay within the range for age and gender.

And, yes, as a result of my research, I have changed my goal

Nat

whoo hoo, then based on your chart, I'm "good." Better than where I started at worse-than-very-poor, for sure.

Every time I've used a body fat calculator chart I have a very different number. PP -- it's 62% (Yes. It's true.) My old awful unreliable cranky Tanita scale would be anywhere from 50 to 56%.

But one of Nat's charts (the YMCA one) says I'm at 38% I like that one. The other one (I've blanked on the name) is....50%

I thought I liked the YMCA one, but on that, if I lose 70 pounds AND 10 inches off my waist (a year's work), I'd only be at 32%. Granted, that's off the Near Death list, but still....

(No, I'm not ready for BFL, really. Not until I can walk up all six flights of stairs without keeling over. But I do have a 10-minute work out book and 3 pound little free weights...baby steps, baby steps.)

The question is -- which method have you all found the most reliable?

Alto, unless you can get your hands (and the rest of you ) measured hydrostatically they are all to be taken with a few grains of nuSalt. What I have been doing is using 3 of the different methods and averaging the numbers. I will be acquiring some callipers shortly and using those, but even this has a 3% margin of error. When you're an athlete and every % counts 3% can make a lot of difference. However, when your goal is to have a healthy BF% I do not think sweating the details is necessary.

What I have learned from my research is this: measurements which take into account more than waist and hips are better. Wrist measurements have been linked to determining BF% so look for ones where this factors in. Ideally height should also be a function - 250 lbs on a 5'6" and 5'9" woman are going to give different %BF.

Nat

Thanks, Nat. I actually have callipers -- came free with a Netrition order. They laughed at me.

I haven't found one that takes wrist measurement into account (mine is 7.25 inches, and that's 98% bone).

It occurred to me that a good addition to this post would be to explain how you could use BF% to figure out your goal weight. The examples below are based on no (or little) increase in LBM (lean body mass) and no (or little) decrease in LBM with goals of 20% BF, 22% BF, and 25% BF.

Assuming a body weight of 215 lbs. and a starting BF% of 40; LBM would be 129 lbs. with 86 lbs. of fat.

At 184 lbs. with a BF% of 30; LBM would be 129 lbs. with 55 lbs. of fat.
At 170 lbs. with a BF% of 25; LBM would be 128 lbs. with 42 lbs. of fat.
At 164 lbs. with a BF% of 22; LBM would be 128 lbs. with 36 lbs. of fat.
At 160 lbs. with a BF% of 20; LBM would be 128 lbs. with 32 lbs. of fat.

By multiplying scale weight by BF% you get your body fat number in lbs. Subtracting that number from your current weight gives you your LBM (LBM being everything other than body fat).

In the above example having a goal weight of 150 lbs. would mean not only a loss of BF but also a loss in LBM. Why is this a bad idea? It's your lean muscle that keeps your metabolism active and high. Sacrificing lean mass at the cost of a number that no one is going to know comes with a high price tag.

At 150 lbs. with a BF% of 22, LBM would be 117 lbs. with 33 lbs. of fat.

Nat

Thank you Nat for all this GREAT INFO!!! I just started weight resistance 2 weeks ago & didnt no where to set my BF goal Im 5"8 do you think 20% is to low for me should I aim around 25 %?Seeing the charts & your info & givin my height I think Im a little to low on my goal. Im not using the BFL method yet but am using a method a Friend who's into weight resistance put together for me.As I just dont have time for the GYM as I run a Daycare.All you Ladies On BFL are doing so GREAT I no its just a matter of time before I try it out. Thanks again!!!!

Melanie, congrats on taking the next step

At 178 w/ 32% BF you have approx. 57 lbs of fat and 121 lbs of lean mass; at 164 w/ 25% BF you'd have 41 lbs of fat and 123 lbs of lean mass. This would mean you'd lose 16 lbs of fat and gain 2 lbs of lean muscle, not a bad trade off. If you had 20% BF at 164 you'd have 32 lbs of fat and 132 lbs of lean mass, a loss of 25lbs of fat and a gain of 11 lbs of lean muscle. You'd still weigh 164 lbs at both BF%'s but you'd be a completely different size. It's all about composition.

By incorporating resistance work into your WOL you have ensured that you won't lose lean muscle - what you're going to lose is FAT. Where you end up, only time will tell, but you are headed in the right direction.

Nat

Thank you so much Nat.I plan on Changing my goal to 140 after I reach my first Goal. I think I am going to just try for 25% for now & see what I look like when I get there.One thing Ive noticed since starting weight resistance is my energy level Has been AWSOME!! Each day Im getting further & further & doing more sets.I Love it & will most deffanatly keep it up.You have a GREAT WEEKEND Were going to the beach & im going to enjoy a 5 mile walk along the shores tomorrow morning.

WELL, AFTER MY GRUELING 7.5 MINUTES OF "OXYCISING " YESTERDAY, WHICH TOOK ME HALF-AN-HOUR (DON'T ASK!), I AM REALLY READY TO GO FOR THE BURN

I WAS READING THIS AND GOT A BIT CONFUSED. WHAT IS THE DIFFERENCE BETWEEN BODY FAT % AND BMI? I WAS GOING TO ENTER MY BMI STATS IN MY PROFILE, THEN SAW THE SPACE WAS FOR BODY FAT %, AND I DON'T KNOW HOW TO FIGURE THAT ONE (NO CALIPERS-WOULD PLIERS DO ).

MY BMI IS 34.3 (WAS 41.3, WITH A GOAL WEIGHT THAT PUTS ME AT 24.6; THINK I'D BETTER LOWER THAT), AND I KNOW THE OPTIMUM FOR WOMEN IS SUPPOSED TO BE 20-25. THERE ARE JUST SO MANY THINGS TO TRY AND FIGURE OUT. I GUESS THE IMPORTANT THING IS TO KNOW THAT I AM *NOT* WHERE I WANT TO BE YET, BUT I *AM* WORKING ON IT!

BTW, I THINK YOU ARE *AMAZING*, NAT.

Beth, BMI and BF are different measurements, you're right. BF% represents the percentage of your body that is not lean mass - that is just fat, only fat, nothing but FAT. Body Mass Index, or BMI, is a measure of weight that takes height into account. While it's possible to have the same BMI and the same BF% it's not necessary. The relation between fatness and BMI is influenced by age and gender. For example, women are more likely to have a higher percent of body fat than men for the same BMI. At the same BMI, older people have more body fat than younger adults.

It's easier if you use and example:

If we take Trainerdans stats and enter them into the BMI calculator we get a BMI of 27.5 - Dan's bodyfat is close to being in the single digits (10%). By BMI standards he's overweight, by body fat % standards he's in amazing shape. Now we've all seen his photos - which measurement do you think is correct here ?

As for measuring BF% online, there are a number of calculators you can use. You should keep in mind that none are 100% accurate. They are useful in monitoring progress over time, however. Pick one and stay with it.

You can find a few of the calculators in this thread

Nat

OOPS, SHOULD'VE CHECKED THAT THREAD FIRST DUH! I MUST SAY THAT, AT THIS POINT, I PREFER MY BMI OF 34.3 TO MY BF% OF 50.7

I JUST WISH I HAD MY ABDOMEN (AS OPPOSED TO WAIST) MEASUREMENT FROM 40 LBS. AGO SO I COULD SEE HOW FAR I HAVE COME. STILL, WE ALL HAVE TO START SOMEWHERE.

BTW, POOR TRAINER DAN; A 27.5 BMI? I NEVER REALISED WHAT A CHUB HE IS. DISGUSTING

THANKS FOR THE HELP, EVEN IF I AM TRAUMATISED BY THE RESULT

Nat: Thank you for posting in my journal about the BF % link! It's been very helpful.

My problem now is that I don't have any calipers, and our little downward financial spiral has made it so I wont be ordering any for some time. I'm going by the CKD parameters calculator, and I know that can be pretty misleading since it goes by waist size and weight. For me, my waist stays a reasonable size while everything below it grows! LOL... You know, the small waist/big butt syndrome! Anyway, according to the CKD calculator the last time I checked my weight (ignoring the scale right now due to my shift in eating recently to a more Zone like approach) I was at 17.7% BF. Sounds like it's low to some people, but it doesn't look right on me and my jeans are a size I still don't want to divulge. LOL.

Anyway, THANK YOU so very much for that information!!!!! It was just what I was looking for!