Eat More. Be More.

Why It’s Important to Know Your Body Fat Percentage

When I started my exercise program I was at 277 lbs and figured I might be able to drop 70 lbs. Once I was down 30 lbs, I realized I may have underestimated. Of course, it was a complete guess in the first place. I mean, when you’ve ALWAYS been fat, how do you know what you should weigh? Those BMI guides are about as useful as a door knob on a wall.


Body Composition

The best way to get an idea of how much you should weigh is to get a body fat composition test done. This will tell you how much of your body weight is fat, and how much is lean mass (muscle, bone, connective tissue).

There are 4 methods. The first uses calipers. If someone is experienced and knows what they’re doing, they can probably get within a few percentage points. Everything depends on where and how they pinch the skin with the calipers. Even the best test is less accurate than the other methods.

The next method uses air pressure. The test I had done years ago involved sitting in a little space pod and then having it pressurized. It did give me a breakdown of muscle vs. fat, and was probably better than the calipers, but still not the best. If this is an option in your area and easier to access than the methods below, go for it.

The most accurate method is a DEXA scan. While is it mainly intended as a bone density screening, it can also measure EVERY fat cell in your body (including fat in the brain, bone marrow and other organs). Scary. Good luck finding a place to do this for you, although it appears the Cooper Clinic in Dallas can do it. I think.

The common standard for testing is hydrostatic weighing. This method involves you being lowered into a “dunk tank” until you are completely submerged. Picture a turkey in a deep fryer, but not as hot. While this is a great way to measure, few people that workout regularly have it done due to the lack of access to testing facilities. It can also be a little expensive, often running $50 or more per visit. My test was $48. If you’re only doing it twice per year, it is worth the cost.

Improving Access To Testing

Technology is a glorious thing. In recent years mobile services have developed that can bring hydrostatic testing to you! When I first heard of this, I immediately pictured a guy with a pick up lining the bed with plastic and filing it with a garden hose. Apparently it’s much more sophisticated than that.


How the Test Works

You start with a dry weight taken with a regular scale like in any doctor’s office. The operator gathers your height and weight. He inputs your info into the software along with age, gender, etc.

Model: Jason Chapman

Model: Jason Chapman

The you sit on the edge, spin your feet around and slide into the water (a wonderful 88 degrees when I did it). There are rails at the bottom to hold onto, and a weighted belt to put across your lap so you don’t float to the surface.

You lean back, chin up, so that only your nose and mouth are above the surface. Then you exhale until you have no more breath. Once the operator taps the side of the tank, you come up. Repeat one more time to verify results and your done.

You immediately receive a report with your numbers that the operator goes over with you and helps set a target goal for the next few months.

Finding a testing Facility

The easiest way to find a location is Google body fat testing in your zip code. There are several mobile services that go out and spend a day at various gyms, companies, or Crossfit boxes.

You can contact the hosting location to see if they have any open times and if so, they may let you take one of those slots to get tested. Our box had a visitor last time because we had an opening. I searched for mobile body fat testing in my city, and it pulled up several companies that would be in my area because most of them maintain a calendar on their website. This is the calendar for the company we used.

My Results

I have a scale at home that tests body fat. How accurate is it? Well, as accurate as a $60 home scale can be I guess. Or so I thought. In January that scale said I was 42% body fat and 26% minutes before the professional test. The hydrostatic test told me I was at 25.8%, so maybe that little scale isn’t so far off after all. Using these numbers I can determine my body fat percentage decreased by 38% (0.258 / 0.42 – 1 = -0.386) and my total body weight dropped 19% (224 / 277 – 1 = -0.19).

The actual amount of fat I have dropped from 116 lbs to 58 lbs. I no longer have to haul around half of the total fat that I did before. This makes climbing stairs, standing and walking at conventions, and even running easier. Having your body fat checked is the only way to know how much actual fat you lost or how much muscle you gained.

My lean mass weighed in at 166.4 lbs and my goal is to be around 10% body fat before I start focusing on adding muscle. It’s hard to add lean mass when you’re running a calorie deficit to lose weight so for now I am trying to maintain what little muscle I do have. If I can add 7 lbs of muscle in the next 6 months, then at 10% body I would weigh 192 lbs by January 6th, 2015. I have to lose another 32 lbs including the Thanksgiving and Christmas holidays. Ouch.

Are These Numbers Important?

Do you have to know your body fat percentage? Of course not. You can look in the mirror and tell if you’re overweight or in shape. But knowing your numbers allows you to accurately measure progress. This is important if you’re working out, especially if you add weight training.

If you are just starting a strength and conditioning program like Crossfit (here’s why I started), the first couple of months can be depressing if net weight loss is your goal. I thought I’d lose at least 20 lbs my first month, yet I only dropped 10. During those first few months you can add a lot of muscle just by kicking your body into gear. So while I didn’t lose as much weight as I wanted, I drastically improved my strength. If I would have had my body fat checked initially and then 3 months later, it would have been much easier to see the progress that I had made.

Knowing your numbers can help you monitor your progress and set goals. It gives you a benchmark to work from and a target to aim for. That alone is worth the cost.

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