New York, Jan 4 (IANS): A team of US researchers has revealed that the pleasure centre of the brain that produces dopamine, and the biological clock that regulates our physiological rhythms, are linked and that high-calorie foods -- which bring pleasure -- disrupt normal feeding schedules, resulting in overconsumption.

The team led by Ali Güler, Professor of biology at University of Virginia, found that mice fed a diet comparable to a wild diet in calories and fats maintained normal eating and exercise schedules and proper weight.

But mice fed high-calorie diets laden with fats and sugars began "snacking" at all hours and became obese.

Additionally, so-called "knockout" mice that had their dopamine signaling disrupted - meaning they didn't seek the rewarding pleasure of the high-fat diet - maintained a normal eating schedule and did not become obese, even when presented with the 24/7 availability of high-calorie feeds.

"We've shown that dopamine signaling in the brain governs circadian biology and leads to consumption of energy-dense foods between meals and during odd hours," said Guler.

"The diet in the US and other nations has changed dramatically in the last 50 years or so, with highly processed foods readily and cheaply available at any time of the day or night," said Guler.

Many of these foods are high in sugars, carbohydrates and calories, which makes for an unhealthy diet when consumed regularly over many years, the authors wrote in the study published in the journal Current Biology.

Half of the diseases that affect humans are worsened by obesity.

This results in the need for more medical care and higher health care costs for individuals, and society, the authors said.