Patent ID: 7720527

Claim:
A subcutaneous fat thickness measuring method, comprising: irradiating a surface of a living body with a first light ray having a first central wavelength falling between 650 nm and 700 nm and a second light ray having a second central wavelength falling between 800 nm and 850 nm, the first and second light rays being irradiated into a same subcutaneous fat layer of the living body and having different absorption levels in blood; receiving, at one site on the surface of the living body, the first and second light rays that have traveled a path through the same subcutaneous fat layer and emerged from the surface of the living body, and measuring the quantity of each of the first light ray and the second light ray received; and calculating the thickness of subcutaneous fat of the living body from the quantities of the first light ray and the second light ray received and measured by using plural relationships between a known subcutaneous fat thickness and quantities of the first and second light rays obtained for different blood concentrations in the known subcutaneous fat thickness, and using as parameters the quantities of the first and second light rays for compensating for measurement errors due to variation of the blood concentration in the subcutaneous fat.