I can't imagine that drinking cold water would make you gain weight! I do know that it is healthy to start your day off with warm lemon water. It helps wake up your digestive tract and flushes it as well. I personally love to drink ice cold water with lemon and fresh ginger in it. It's so refreshing and good for you as well! The most important thing is that drinking water is the best choice over any other beverages - especially juices and sodas.