Optical methods and devices are provided for the reduction of the lipid content of adipocytes without significant heat or intolerable adverse effect on the cells and their surrounding tissues. The optical method and device can be used to irradiate adipose tissue through the skin with non-thermal and non-destructive effects by application of near infrared (NIR) irradiation at selected wave bands in selected ranges to affect modulation of innate enzymatic processes involved in lipolysis, lipogenesis, leptin secretion, adiponectin secretion, and/or glucose absorption.
