The study in mice suggests that the functioning of the body's internal 24-hour clock, which regulates our sleep/wake cycle and the timing of hunger pangs, is closely tied to the rhythms of certain metabolic processes.

A Western-style diet with a lot of calories from saturated fat can disrupt the body's clock or circadian rhythms, setting up a vicious circle which throws off the timing of certain metabolic processes, potentially increasing the risk for obesity and diabetes.

"Timing and metabolism evolved together and are almost a conjoined system," said Joe Bass, lead author on the paper and an endocrinologist at Northwestern University in Chicago.

"If we perturb the delicate balance between the two, we see deleterious effects," he said in the study published in the journal Cell Metabolism. © 2007 Australian Broadcasting Corporation