Life Expectancy vs. BMI

America is clearly losing the war on obesity, not only in adults but also in children. Around 68 percent of adults over age 20 and 17 percent of children between the ages of 6 and 19 weigh more than they should, the National Institute of Diabetes and Digestive and Kidney Disorders reports. Medical reports have focused on the impact of overweight in both children and adults on life expectancy.

Body Mass Index Definition

Body mass index is a way of determining whether a person is overweight by evaluating total body fat percentage. The formula for calculating BMI, where BMI equals weight in pounds ÷ (height in inches --- height in inches)] x 703 is easily determined by using online calculators that require input of your height and weight. A normal BMI falls between 18.5 and 24.9; if your BMI falls between 24.9 and 29.9, you're considered overweight. If your BMI is over 30, you're considered obese. A BMI of less than 18.5 is considered underweight.

Related Diseases

Being overweight or obese is associated with a number of diseases which can impact your life expectancy, including heart disease, Type 2 diabetes, obstructive sleep apnea, high blood pressure, certain cancers and abnormal lipid levels.

Life Expectancy Impact

An Oxford University study published in the March 18, 2009 "The Lancet" and reported by Science Daily analyzed data from 57 different research studies that followed around 1 million people for 10 to 15 years. The study found that moderate obesity or a BMI between 30 and 35 reduced life expectancy by around three years, while severe, or morbid obesity, a BMI of 40 to 50 shortened life by 10 years.

Contributing Factors

Both race and sex, as well as age, contribute to years of life lost due to obesity in a study reported in the "Journal of the American Medical Association" by lead author David Fontaine, Ph.D., of Johns Hopkins University School of Medicine. In general, the number of years of life lost due to obesity was higher for men than women. Blacks were less affected by obesity in terms of years of life lost than whites, with a decrease in life expectancy not found until the BMI reached 32 for men and 37 to 38 for women. Morbid obesity at a younger age also resulted in a greater number of years of life lost

Considerations

Life expectancy has greatly increased since the beginning of the 20th century, with the average life expectancy of 49.2 years in 1900 to 1902 increasing to 77.3 in 2003, according to the Centers for Disease Control and Prevention. The explosion in obesity rates, particularly among children, could begin to reverse overall life expectancy and result in the first drop in life expectancy in more than 100 years if obesity trends don't decrease, a study conducted by the National Institute on Aging warns.