Drinking ice water (39 F) increases resting metabolism and burns more calories. Israeli scientist gave obese 9 year old children a glass of ice water and found that resting metabolic rate increased by one kilocalorie per minute for nearly an hour. This doesnt sound like much but normal resting metabolism is only about 1.5 calories per hour.
Ice water is not magic bullet against obesity, but it might help a little. This research group found similar results in adults.