Overweight (excess weight) and obesity (excess body fat) are commonly assessed by reference to the Body Mass Index, which measures the relationship between height and weight. Although the Body Mass Index has drawbacks (eg. it doesn't measure body fat), it is a useful guide to weight-related health risks.
To Calculate Body Mass Index
- Simply divide your weight (pounds) by your height (inches) squared.
Multiply the result by 705.
- if you weigh 160 pounds with a height of 5 feet 4 inches (64 inches), the body mass index formula runs:
Step 1. (160) divided by (64 x 64 = 4096) = 0.039
Step 2. 0.039 x 705 = 27.4
Result: Your body mass index is 27.4 (overweight).
Normal Weight, Overweight or Obesity
· Normal weight means having a body mass index of 19-24.99
· Overweight means having a body mass index of 25-29.99
· Obesity means having a body mass index of 30+
Facts About Overweight
· Less than half of U.S. adults have a healthy weight.
· Almost two-thirds of U.S. adults are overweight. 
· All adults (20+ years old): 129.6 million (64.5 percent)
Women (20+ years old): 64.5 million (61.9 percent)
Men (20+ years old): 65.1 million (67.2 percent)
Facts About Obesity
· Nearly one-third of U.S. adults are obese (BMI > 30).
· All adults (20+ years old): 61.3 million (30.5 percent)
Women (20+ years old): 34.7 million (33.4 percent)
Men (20+ years old): 26.6 million (27.5 percent)
Overweight and Obesity Trends
· The prevalence of overweight and obesity in adults has steadily increased over the years among both genders, all ages, all racial/ethnic groups, all educational levels, and all smoking levels.
· From 1960 to 2000, the prevalence of overweight (BMI > 25 to <>
· The prevalence of obesity (BMI > 30) during this same time period more than doubled from 13.3 to 30.9 percent, with most of this rise occurring in the past 20 years
· From 1988 to 2000, the prevalence of extreme obesity (BMI > 40) increased from 2.9 to 4.7 percent, up from 0.8 percent in 1960.
· The prevalence of overweight and obesity generally increases with advancing age, then starts to decline among people over 60.