Body Fat: definition, measurement, and risks associated

Body composition refers to the relative percentage of body weight that is fat and fat-free tissue. There are many techniques and procedures available for determining your body fat percentage. Different methods and techniques are very tricky and the ability for error can be wide depending on your technician and method used.

The most frequent tests you hear now or see in health clubs are the bioelectrical impendence machines, which resemble a weight scale. There are also other methods such as skin-folds and underwater weighing. The methods we will use here are based on anthropometric methods and can be done at home.

Body Mass Index

The body mass index (BMI), or Quetelet index, is used to assess weight relative to height and is calculated by dividing body weight in kilograms by height in meters squared (kg/m2). Obesity-related health problems increase beyond a BMI of 25 for most people, and the Expert Panel on the Identification, Evaluation, and Treatment of Overweight and Obesity in Adults lists a BMI of 25.0 to 29.9 kg/m2 for overweight and a BMI of greater than or equal to 30.0 kg/m2 for obesity. The standard of error for determine body fatness from BMI is plus/minus 5%.

Remember that to convert body weight in pounds to kilograms you must divide by 2.2. So 150 pounds is 68 kilograms. 1 meter = 39.37 inches. So if you’re 64” that would be 1.6 meters. So for someone 150 pounds and 5’4” the calculation would be 68/1.62 or 68/2.56 = 26.5.

Waist-to-Hip Circumference

Where body fat distributes on the body is an indicator of obesity and health risks. Individuals with more fat on the trunk, especially abdominal fat, are at increased risk of hypertension, type 2 diabetes, hyperlipidemia, coronary artery disease, and premature death compared with individuals who are equally fat, but have more of their fat on the extremities. The waist-to-hip ratio has been used to determine the body fat pattern.

The waist is measured at the narrowest part of the torso (above the belly button and below the xiphoid process). The hip measurement is the maximal circumference of the hips or buttocks region, whichever is larger. The WTHR is determined by dividing the waist measurement by the hip measurement. For example, someone with a waist measurement of 33 and a hip measurement of 44 would have a WTHR of .75.

The health risk for young men is a ration of .94 and over. For young women, a ratio more than .82. For ages 60-69 years, WTHR values are greater than 1.03 men and .90 women for health risk classification.

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