I heard from someone today that drinking ice water causes your body to burn 100 calories to heat it up. Any ideas whether this is a fact or myth?

I'm going for myth here. You may be confusing calories and kilocalories. The calories referred to in food is actually 1000 heat calories. The body will have to warm the water up a bit, but not that much. Don't want to get into a thermodynamic discussion, but sorry to burst your bubble. It would take about 6 food calories to raise a cup of cold water to body temperature.

didn't burst my bubble. I didn't think so either, just wanted to hear what others had to say.