Original: In 1988 a NIH report concluded that a BMI over 25 is overweight and a BMI over 30 is obese. In the 1990s the World Health Organization (WHO) decided that a BMI of 25 to 29 should be considered overweight and a BMI over 30 is obese, the standards the NIH set.
Simplified: For example, in the United States in 2007, 74% of adults had a BMI above 25 (Overweight or Obese) and 27% of adults had a BMI above 30 (Obese).