It’s All About Dat Fat
According to the Academy of Nutrition and Dietetics, it is not what you weigh that matters, at least in regards to your health. It’s your body fat.
Here’s what Laurie Wright, assistant professor of nutrition at the University of South Florida, has to say about it:
“While most people who are ‘overweight’ also are ‘over fat, it’s the fat that’s dangerous. You also can be ‘skinny fat.’”
Meaning, you can be a normal weight but still have too much fat and too little muscle.
What about BMI?
The Annals of Internal Medicine recently published findings of a research team from Canada that indicate it’s not about BMI, either.
The Canadian study included more than 50,000 subjects. The researched captured three metrics from each subject: weight, BMI (percentage of weight in relation to height), and body fat percentages obtained from scans. What they found was that the subjects with the most body fat—on the basis of the scans—were more likely to die in a few years, regards of weight or BMI.
In fact, BMI is looking more and more like a crude measure at best, that may have very little use as a health indicator. Remember, BMI is percentage of weight in relation to height, regardless of body composition.
For example, let’s say there are two people in the doctor’s office. Both weigh 220 pounds; both are six feet tall. One appears to be overweight; the other, a bodybuilder, does not. Their BMIs, however, are identical. That’s why BMI is not a good health indicator.
So it’s not about how much you weigh, and it’s not about BMI. But don’t run out for pizza and ice cream just yet. Weight and BMI may not matter, but size does.
Does size matter?
When it comes to waist size, yes. According to some medical professionals, a good old-fashioned tape measure around the waist can tell you all you need to know about your body composition.
Waist measurement correlates very highly with body fat and is a measure of the most dangerous type of body fat which is visceral (belly) fat. According to the US Centers for Disease Control and Prevention, waist sizes of more than 40 inches in men, and 35 inches in women are linked to increased risk for heart disease as well as type 2 diabetes.
If you want a more comprehensive look at your body fat composition, the best way to do that is to find out your body fat percentage (BFP).
What is BFP?
Body fat percentage is just what it sounds like—the amount of fat in your body compared to everything else, without regard to height or weight. According to all the latest research, BFP is the most important health indicator when it comes to body composition.
What is a healthy BFP?
The range of healthy BFPs differs between men and women. In general, athletic or fit women maintain ranges of 14% to 24%, while athletic or fit men see ranges of 6% to 17%. One U.S. government study found average levels of 40% fat for women and 28% fat for men.
In general, an acceptable BFP for women is 25-30%. For men, it is 18-25%.
How do you measure BFP?
There are several ways to measure BFP, at varying levels of accuracy, expense and practicality. We’ll start with the most accurate and work our way down.
- DEXA Scanning
DEXA Scanning is arguably the most accurate way to measure BFP. It involves lying on a table for around ten minutes while a special X-ray machine scans your body composition. This method generally takes place in a health facility.
- Bod Pod
Another highly accurate method involves something called a Bod Pod. It’s a space-age egg-shaped contraption that you are sealed into. It uses a plethysmograph air displacement thingie to measure your body mass, volume, and density. Takes about five minutes. There is a little window you can look out that helps if you’re claustrophobic. It is pretty cool and very accurate.
This method generally takes place in a fitness facility or university setting.
- Biostatic Testing
Then there’s a water displacement test that is supposed to be just as accurate as the first two. It involves being submerged in a water tank a few times while some sort of machine measures your fat and fat-free body mass, as percentages and in actual weight. The tank looks somewhat like a metallic bathtub, and the test takes around twenty or thirty minutes. Most biostatic machines also tell you all kinds of other helpful stuff like how much fat you need to lose, how many calories per day you (personally) burn without exercising, how many you burn from different activities, and where you are on a scale of ideal body fat for your age and gender.
There are some stationary and mobile facilities that offer biostatic testing, you just have to find them.
- Fitness Calculators
The US Navy and YMCA both have formulas that estimate your body fat percentage using measurements and other data. Fitness calculators can be found online, have no associated cost and are easy to use. They are useful for providing consistent measurements to monitor body composition changes over time.
The YMCA method uses waist size, weight, and gender. The US Navy formula uses waist, hip and neck size, weight, height, and gender. Both estimate your percentage of body fat, how much of your weight is lean mass and how much is fat mass, and your general fitness category. Both are said to be accurate within 1-3% for most people.
It is important to note, however, that no body fat percent calculator will be very accurate for individuals with a very muscular build.
This method involves using calipers to measure a pinch of fat from various areas of the body. The three-fold method measures three areas of the body: triceps, thigh, and suprailiac (what most of us call love handles). This approach has the advantage of being cheap (calipers run about $5) and practical, because it can be done at home with the same person measuring each time, allowing consistent metrics to monitor body composition changes over time.
- Body Fat Scale
Some of the newer digital scales display a BFP by using a technology called bioelectrical impedance to detect fat levels. However, they have been known to give inconsistent and skewed results depending on how hydrated you are at the time you step on the scale.
Summary of BFP Measurement Methods
|Method||How it works||Accuracy||Cost||Convenience / Practicality|
|DEXA Scanning||Dual x-ray procedure||Highest||High||Low|
|Bod Pod||Air displacement||High||High||Low|
|Algorithm using body measurements, gender, and height||Medium||No cost||High|
|Calipers||Skin folds measurement||Medium||Low||High|
|Body fat scale||Biometrical impedance analysis via electric current||Low||Medium||High|