While drinking a glass of cold water burns more calories than one at room temperature, it's only about eight calories, so it's not exactly a weight-loss miracle. Even though cold and warm water are equally hydrating, the idea behind drinking cold water is that since it's so cool and refreshing, it's more satisfying after a workout, so you're likely to drink more, which makes for more effective hydration.
Drinking a glass of warm or even hot water before a meal can make you feel fuller quicker, so you'll end up consuming less food. Actually, when you're feeling like snacking, sipping a glass of water first is a good habit to get into since dehydration symptoms like low energy, dizziness, and headaches are often mistaken for hunger. Drinking 16 ounces of water before meals has also been proven to help with weight loss, so there's another reason to keep that reusable bottle filled.