Age and gender need to be taken into account in determining whether you are underfat health range overweight or obese.
For women:
Age 20-40: Underfat – Under 8%; Healthy range 8-19% Overweight 19-25% Obese over 25%
Age 41-60: Underfat – Under 11%; Healthy range 11-22% Overweight 22-27%; Obese over 27%
Age 61-79: Underfat under 13%; Healthy range 13-25%; Overweight 25-30%; Obese over 30%
For men:
Age 20-40: Underfat Under 21%; Healthy range 21-33%; Overweight 33-39%; Obese over 39%
Age 41-60: Underfat 23%; Healthy range 23-35%; Overweight 35-40%; Obese Over 40%
Age 61-79: Underfat Under 24%; Healthy range 24-36%; Overweight 36-42%; Obese over 42%
How are these definitions determined?

