Body Mass

August 1, 2011

Index Obesity is an important risk factor for many illnesses, especially heart disease and diabetes. However, body weight alone is not the best way to determine whether an individual is overweight. Whether the number of pounds a person carries is healthy or not depends on one’s height and the amount of fat compared to the amount of muscle. The relationship between the amount of fat and muscle, weight and height is referred to as body composition. Extremely precise measures of body composition involve elaborate procedures such as underwater weighing or taking multiple measurements of the width of skin that can be “pinched” off the person’s frame in numerous locations on the body.

The body mass index (BMI) is a much simpler way to estimate body composition and obesity by relating body weight to height. Indirectly, BMI measures body composition because a strong relationship has been found between the amount of body fat and BMI. BMI is often used to assess the level of health risk for obesityrelated diseases. The equation used to calculate BMI is

BMI = body weight in kilograms / (height in meters)2

A BMI that is lower than 18.5 is considered underweight. Healthy, fit persons have BMI values from 18.5 to 24.9. When the BMI is between 25.0 and less than 30.0, a person is considered to be overweight. An individual with a BMI between 35 and 40 is considered obese. Extreme or “morbid” obesity is defined as a BMI of 40 or greater. People with BMIs above 30 have an increased risk for heart disease and adult-onset diabetes.

To reduce BMI, and therefore reduce the risk of illness, the best solution is to follow healthy eating and exercise guidelines, provided by your physician or a certified dietician/nutritionist. Particularly important is increasing the amount of low-fat protein, vegetables, and fruits in the diet, eating less high-fat or high-sugar foods, and engaging in aerobic exercise such as vigorous walking, jogging, bicycling, aerobic dance, or swimming.

SEE ALSO: Cardiovascular disease, Diabetes, Diet, Obesity, Weight control


Category: B