Body weight is used as an indicator of an individual's health. It is usually compared to tables that list "ideal" or "desirable" weight ranges for specific heights. Some of these tables use values gathered from research studies, while some include the heights and weights of individuals who have bought life insurance (e.g., the Metropolitan Height and Weight Tables). An individual's weight can be described as a percentage of the ideal or desirable weight listed, and can also be categorized as healthy, underweight, , or . An additional method of comparing an individual to a population group is with the .