Underweight = below 18.5
Normal weight = 18.5 – 24.9
Overweight = 25 – 29.9
Obesity = 30 or higher
Class 1 obesity = 30 – 35
Class 2 obesity = 35 – <40
Class 3 obesity = 40 or higher
The BMI scale for children and adolescents up to age 19 is age adjusted because as children progress through adolescence it is normal and healthy for them to be at a higher weight at any given height than a younger child. We also know that older adults often have declining skeletal muscle and changes in their body composition that put them at increased risk for cardiometabolic disease even at a healthy BMI; however, the standard BMI scale is still used.
BMI cannot tell us an individual’s body composition. Over-reliance on BMI to the exclusion of other more sensitive and specific screening tools may cause healthcare professionals to falsely identify some people as having health risks based on an elevated BMI (athletes and bodybuilders for example) while missing others who do have real health risks because of high body fat but whose BMI is still within a healthy range. Furthermore, it has been found that people from certain ethnic backgrounds have greater body fat percentages than accounted for by the BMI chart making these standard charts less reliable for Asian, Hispanic, and African populations.
When the BMI is rising or noted to be elevated, other screening or diagnostic testing may be warranted: cholesterol and blood sugar tests for example. The United States Preventative Services Task Force recommends that healthcare professions refer those individuals with a BMI over 30 for a comprehensive approach to weight loss. The obesity medicine specialists who direct and deliver such comprehensive weight management programs are trained to rely on more sensitive tools to assess obesity.
Technologies that assess actual body fat percentage such as bio-impedance scales are superior to BMI for evaluating health risk. In addition, equations such as the waist to hip ratio and the newer waist to height ratio are more sensitive tools that detect cardiometabolic risk factors even in persons with normal BMI.
At Aspect Wellness, we use SECA Bio-Impedence Body Composition to assess your baseline body composition and track how well you are preserving skeletal muscle while reducing excess stored fat.
