Is There a Better Alternative to Measuring BMI?

Other measurements commonly used in clinical and community settings include:

Waist circumference

It measures the amount of fat surrounding the abdomen, basically waist circumference.

You can measure weight circumference in the following ways:

• Use a measuring tape.
• Surround the measuring tape at the natural waist, that is, in between the lowest rib and top of the hip bone or at the navel button.
• Waist circumference more than 35 inches in women (34 inches in Asian women) and 40 inches (36 inches in Asian men) in men indicates higher abdominal fat. Higher abdominal fat is associated with several chronic diseases.

Some benefits of measuring waist circumference include:

• Easy to measure and requires a measuring tape
• Inexpensive
• Abdominal fat is an ideal indicator to measure body fat
• Studies have confirmed that waist circumference can predict disease development and health

Some of the downsides of this measurement include:

• There’s been no standardization for this type of measurement
• Nonavailability of standard reference data for waist circumference in children
• Measuring is difficult and yields less accurate results in individuals with a BMI of 35 or higher
• Doesn’t consider different body types and builds

Waist-to-hip ratio (WHR)

Like waist circumference, WHR is a powerful indicator that measures abdominal obesity.

You can measure WHR in the following ways:

• Measure the waist circumference.
• Measure the hip at its widest diameter.
• Divide waist measurement to hip measurement.

WHR above 0.80 in women and 0.95 in men indicates higher fat storage in the abdomen, increasing the risk of heart and chronic diseases.

WHR lower than 0.80 in women and 0.95 in men suggests higher fat storage in the hip. Higher hip fats indicate that the person is in good health.

Some benefits of measuring WHR are as follows:

• Easy to measure
• Inexpensive
• Better association with body fat as measured by the most accurate methods
• Studies have confirmed that WHR can predict disease development and health in adults

Some of the downsides of this measurement are as follows:

• Chances of measurement errors are high because it requires waist and hip measurements
• Measuring the hip is tedious compared with measuring the waist
• Interpretation is more complex than waist circumference because WHR can be influenced by abdominal fats and lean muscle mass around the hips
• Because measurements are expressed in ratios, there are chances of loss of information. Two individuals with different BMI could end up having the same WHR
• Measuring is difficult and yields less accurate results in individuals with a BMI of 35 or higher
• Doesn’t consider different body types and builds

Skinfold thickness

This technique measures fat beneath the skin at various sites and estimates total body fat. 

The steps involved in this type of measurement are as follows:

• Use a special caliper to measure the skin fat
• Gently pinch a fold of skin and squeeze caliper around it until a click sound is heard
• Measure at five to seven different locations such as:
  • Trunk
  • Thighs
  • Front and back of the upper arm
  • Under the shoulder blade
  • Back
• Calculators are available online where you enter these values, and the fat percentage is displayed

Some benefits of measuring skinfold thickness are as follows:

• Fast and easy (except in individuals with a BMI of 35 or higher)
• Convenient
• Safe
• Inexpensive
• Portable

Some of the downsides of this measurement are as follows:

• Less precise or reproducible compared with other methods
• Measuring is difficult in individuals with a BMI of 35 or higher

Some of the sophisticated methods used for measuring body fat are as follows:

• Bioelectric impedance: It uses a small and safe electric current through the body measuring resistance. The higher the body fat, the higher is the resistance.
• Air-displacement plethysmography: It uses the principle of underwater weighing but is done in the air instead of water. Individuals sit in a small chamber wearing bathing suits.
• Hydrometry: Individuals drink isotope-labeled water and give body fluid samples. These samples are then analyzed for body water, fat-free body mass, and body fat mass.

Body mass index (BMI) is a person’s weight in kilograms divided by the square of height in meters. It indicates the amount of body fat.

BMI is the most inexpensive screening tool to measure body fat. Although it does not directly measure body fat, it can be correlated with more direct measures of body fat.

Various categories of BMI include:

• BMI value less than 18.5 kg/m2 are considered underweight
• BMI values from 18.5 to 24.9 kg/m2 are healthy
• BMI values from 25 to 30 kg/m2 are overweight
• BMI higher than 40 kg/m2 are considered obese

To use this calculator:

1. The default BMI of 16.6 shown on the tool is for a 5'5" person who weighs 100 lbs.
2. Use the switch on top to pick either metric or imperial measurements.
3. Set the height and weight dials to match your own height and weight.
4. View your BMI number at the center of the tool and see where you fall on the obesity chart.

BMI values are based on clinical data about averages for these measurements across a wide swath of people.

The body mass index (BMI) is used to assess your weight relative to your height. This BMI calculator allows you to easily screen yourself for obesity or extra, unhealthy weight. If your results from the calculator aren't in the healthy range, don't worry too much. People with muscular builds may be classified as obese, even with a low body fat percentage and optimum health, simply because the BMI formula uses only two data points.

There are several limitations associated with using body mass index to assess body fat because it doesn’t consider:

• How muscular you are.
• Your activity level and distribution of fat in your body.
• Your body type because people with fat in the abdominal area (people who have an apple-shaped body) are more prone to chronic health diseases.
• Your age because older people who are a bit overweight tend to have better survival than those who are leaner.
• Your ethnicity because Asian Americans are at a high risk of diabetes.