The body mass index, or BMI, is a calculation used to determine your level of body fat. It can help a doctor determine your overall fitness and your risk of developing chronic diseases. Still, BMI is not the only factor your doctor considers, and it isn’t a completely reliable assessment for every body type.
What the Results Mean: Generally, if you’re at a healthy weight, your body mass index should fall between 18.5 and 24.9, notes the National Heart, Lung and Blood Institute. If your BMI is below 18.5, you could be underweight. On the other hand, a BMI greater than 25.0 is categorized as overweight, while a score above 30 is considered obese.