A man walks past the New York Stock Exchange after trading hours in New York August 17, 2009.

WASHINGTON, Sep 4 (Reuters) - Midnight raids on the refrigerator may have worse consequences than indigestion -- a study in mice boosts the theory that when you eat affects whether the calories go to your hips or get burned off.

Mice fed during the daytime -- when they normally would be sleeping -- gained more weight than mice fed at night, Fred Turek of Northwestern University in Illinois and colleagues found.

They ended up weighing 7.8 percent more than night-fed mice. This held even though the mice were fed identical amounts of food and exercised the same amount, they said in the study published on Friday in the International Journal of Obesity.

"Simply modifying the time of feeding alone can greatly affect body weight," they wrote.

"Mice fed a high-fat diet only during the 'right' feeding time (i.e., during the dark) weigh significantly less than mice fed only during the time when feeding is normally reduced (i.e., during the light)."

The finding might help people trying to lose weight, the researchers said.

It may be possible to simply change the timing of meals and snacks, they said. That could mean eating more in the daytime and cutting back on the late-night ice cream.

(Editing by Xavier Briand)