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Buff Vs Obese, Why BMI is confusing to muscular people

Yesterday I wrote a post on the topic of stubborn belly fat titled: Why is it so hard for skinny people to shed the last few pounds?

During the post I talked about how people get too obsessed with trying to weight a specific amount because they have been looking at BMI charts and think that they need to be a specific weight in order to be healthy / attractive.

On the right here you see two cartoon people, both are 6 feet tall and both weigh 250 lbs. Lets call them Dave and Bob.

Dave is extremely muscular and weighs a hefty 250 lbs. Bob in contrast, weighs the same amount but has a lot more fat than muscle. The trick here is that fat takes up more space than muscle, because muscle is actually heavier than fat. 1 lb of fat takes up lots of space, whereas 1 lb of muscle takes up very little space. Thus even though they look very different, Dave and Bob still end up weighing the same.

And having the exact same BMI measurement of 33.9. Which is so heavy it isn't even on the chart below, because this chart only goes up to 215 lbs.

But what we do know is that 33.9 is in the low 30s, so that is the lower half of obese which ranges from 30.0 to 39.9. 40.0 or higher would be extremely obese.

However there is an obvious problem. Nobody in their right mind would call Dave obese. He looks like a bodybuilder. Thus the BMI chart is flawed because it ignores the possibility that a person might have more muscle mass (or possibly even more bone density, which is a factor people often ignore).

Thus we need better ways of measuring body weight / obesity. Well luckily there are ways to do that.

The following three methods are recommended.

#1. Body Adiposity Index

BAI multiplies your hip circumference by your height. Although clinical studies have not shown any proof, it is widely believed that Body Adiposity Index is more accurate than BMI as the resulting figures are approximate. BAI is also useful in areas whenever scales are not be available.

#2. Waist Circumference Measurement

Ah, the old fashioned tape measure. By measuring the natural waist you can get a good indication of the amount of abdominal fat you are carrying. Knowing the circumference of your waist can help determine your risk of getting heart disease and other medical conditions. According to physicians, the following figures indicate individuals in the 'at risk' group:

Women with a waist circumference of 35 inches and over.
Men with a waist circumference of 40 inches and over.

#3. Waist-to-Hip Ratio

The waist-to-hip ratio is not only an excellent way of calculating how much excess weight you are carrying, it can also be used to indicate susceptibility to a number of health issues, including high blood pressure, heart disease and diabetes.

Using a tape measure, take a reading from your natural waist line and the widest part of your hips. Now divide the circumference of your waist by your hip circumference measurement. The World Health Organization considers abdominal obesity is represented by a waist–hip ratio above 0.90 for males and above 0.85 for females.

The following two methods are NOT recommended.

#4. Hydrostatic Weighing

Hydrostatic weighing is NOT an effective way of calculating body fat. The weighing process takes place underwater on a chair that is placed on a zeroed out set of scales. You then sit on the chair before exhaling all the air from you lungs and then placing your head underwater. Once the scales stabilize, your weight is then noted down. The resulting figure is then passed through a series of formulas which, ultimately, produces a body-fat reading based on the buoyancy of your body fat. That is a hugely inaccurate way of measuring body fat however as it ignores muscle buoyancy, ignores bone density, ignores how much air might be in your lungs, etc. So don't bother.

#5. Body Fat Measuring

By using a special set of callipers skin and fat measurements are taken from the waist, shoulder blades, biceps and triceps. The resulting readings, in millimeters, are added up to produce a single figure. The figure is then plotted against a chart that takes the patient's sex, age and measurement into consideration to determine the body-fat percentage figure. In theory the higher the body fat, the higher your risk of suffering from obesity-related conditions. However this method also suffers from inaccuracy as it also is confused by measurements due to saggy skin / very elastic skin, a more muscular physique, and even factors like disproportionate body shape.



Conclusions? Maybe stop worrying about the numbers and just exercise because you enjoy feeling healthy. It doesn't matter HOW you do it. Just enjoy doing it.


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