A method for noninvasive analysis of subcutaneous tissue includes irradiating a surface of the tissue with short wave infrared (SWIR) radiation in a first spectral band that is strongly absorbed by water, and with SWIR radiation in a second spectral band such that an interaction of the radiation in both spectral bands with a component of the tissue other than water is substantially identical. An intensity of the radiation in each of the spectral bands that emerges from the tissue is measured. A relative absorption by the tissue of radiation in one of spectral bands relative to absorption by the tissue of radiation in the other of the spectral bands is calculated. A state of the tissue is determined in accordance with the calculated relative absorption.