Obesity is characterized by excess body fat; the condition is currently considered to be at epidemic levels in the United States and many other countries around the world. Studies have shown that being obese is associated with an increased risk of death from causes such as hypertension, stroke, heart disease, and other conditions.
Obesity is typically measured by body mass index, or BMI, a value calculated as weight in kilograms divided by height in meters squared. Adults with a BMI greater than 25 kg/m2 but less than 30 kg/m2 are considered overweight, while adults with a BMI greater than 30 kg/m2 are considered obese. An adult who is more than 100 pounds overweight or has a BMI greater than 40 kg/m2 is considered morbidly obese.
For children, what is considered a healthy BMI varies with the age and gender of the child. According to the Centers for Disease Control and Prevention (CDC), children with a BMI at or above the 85th percentile are considered overweight, while those with a BMI at or above the 95th percentile are considered obese.
In 2016, the CDC reported that 93.3 million adults and 13.7 million children were overweight or obese. Rates of obesity have gone up from 12 to almost 40 percent of the population since 1991. The percentage of youths who are overweight has more than doubled in the past 20 years. Eighteen percent of children and adolescents between 2 and 19 years old are now considered obese.
Research has shown that being overweight is significantly associated with an increased risk of death from hypertension, dyslipidemia (high cholesterol), type 2 diabetes, stroke, osteoarthritis, coronary heart disease, gallbladder disease, sleep apnea and respiratory problems, and endometrial, breast, prostate, and colon cancers.