The effects of both dietary obesity and a food deprivation period of 24 hours on fatty acid composition of brown adipose tissue have been investigated. Long time exposure to a hypercaloric high-fat diet such as the cafeteria diet induced an important tissue fatty acid accumulation, mainly for the major saturated and monounsaturated fatty acids. Notable metabolic differences have been observed in the behaviour of control and obese rats facing a food deprivation period: a preferential utilization of the most abundant saturated fatty acids in control rats and a minor response in obese rats, with a greater fat accumulation in the interscapular brown adipose tissue.