Waist size and BMI serve as general indicators of a person's fat composition: these measurements indicate to patients and physicians where people fall in the spectrum of weight, which ranges from underweight to overweight and obese. Doctors use body mass index, or BMI, as a general guideline for determining whether people must lose, maintain or gain weight. The BMI index identifies body composition, calculating fat percentage and comparing it to individuals of the same age and gender within a given population; deviations or proximity to the standard measurements help doctors determine the normalcyof a person's weight-to-height ratio.
BMI, which considers weight and height, serves as an accurate and reliable indicator of body fat composition, according to the Centers for Disease Control. Ideal BMI standards exist uniformly for men and women, and remain the same among all age groups. These standards classifyBMIs between 18.5 and 24.9 in the normal range. Having a BMI below 18.5 classifies as being underweight, while physicians consider people withBMIsbetween 25.0 and 29.9 overweight. Those with BMIs exceeding 30 qualify as obese.
Waist circumference indicates the amount of abdominal fat, which in turn identifies the likelihood of people developing weight-related health issues. Men with waists exceeding 40 inches and non-pregnant women with waists of more than 35 inches face a higher risk of obesity-related complications, such as heart disease, high cholesterol and blood pressure, and diabetes.