Myth: If my Body Mass Index (BMI) is high, I should start trying to lose weight.

Answer: Maybe

Body Mass Index, or BMI, is a calculated number that is used to assess overweight and obesity, as well as health risks for chronic disease. It is based on a person’s weight and height. To calculate, you’ll need to divide your weight (in kilograms) by height squared (in meters²). An easier way to determine your BMI is to use the National Heart, Lung and Blood Institute’s online calculator. The following BMI ranges indicate your weight status:

• Normal weight = 18.5 – 24.9
• Overweight = 25 – 29.9
• Obese = 30 or greater

BMI is a good general tool to assess health status; however, it is not appropriate for everyone. Healthy adults who exercise heavily, such as highly trained athletes, have a significant amount of muscle mass and will have higher BMIs despite having a low percentage of body fat. This occurs because muscle weighs more than body fat. Additionally, the BMI ranges are also not appropriate to use for children. A pediatrician will use BMI-for-age growth charts that are specific for boys or girls. These charts are used for children and teens, ages 2 – 20 years of age.

Always check with your doctor before starting a weight loss regimen. For more information about achieving and maintaining a healthy weight, check out MissouriFamilies.org.

Contributor: Mary Wissmann, MS, RD, LD, Nutrition and Health Education Specialist, St. Louis County, University of Missouri Extension, WissmannM@missouri.edu