BMI is an indicator of the amount of body fat for most people. It is used as a screening tool to identify whether an adult is at a healthy weight in kilograms is divided by height in meters squared (kg/m2). In studies by the National Center for Health Statistics, BMI values less than 18.5 kg/m are considered underweight. BMI values from 18.5 kg/m to 24.9 kg/m are healthy. Overweight is defined as a body mass index of 25.0 to less than 30.0 kg/m. People with BMIs in this range have an increased risk of type 2 diabetes, hypertension, and cardiovascular disease. Obesity is defined as a BMI of 30.0 kg/m or greater. People with BMIs of 30 kg/m or more are at higher risk of cardiovascular diseases. Extreme obesity is defined as a BMI of 40 kg/m or greater.Some well-trained people with dense muscle mass may have a high BMI score but very little body fat. For them, the waist circumference, the skinfold thickness or more direct methods of measuring body fat may be more useful measures than BMI.