Normal weight is represented by a body mass index, or BMI, between 18.5 and 24.9, according to the National Heart, Blood and Lung Institute. A BMI below 18.5 means a person is underweight, a BMI between 25 and 29.9 means a person is overweight, and a BMI greater than 29.9 indicates that a person is obese.
BMI is calculated by putting a person's weight and height into a specific formula, according to the Centers for Disease Control, and it is a way to measure a person's "fatness" without any special tools or seeing a dietitian. However, BMI is only a guide and does not directly measure a person's body fat. People who fall within a normal weight range can have a high percentage of body fat that puts them at risk for health problems, such as heart disease and obesity, according to Mayo Clinic. This is known as normal weight obesity.
People with normal weight obesity may consider losing body fat, but as of 2014, the exact body fat limits for a person with normal weight obesity are not yet known, according to Mayo Clinic. WebMD reports that an acceptable body fat percentage is between 18 to 32 percent for women and 10 to 25 percent for men.