Maintaining your temperature burns a lot of calories. People who want to lose weight can do so faster by forcing their bodies to burn more calories to stay warm. You would do well to do the opposite, so long as you don't take it so far as to actually need a light jacket to feel comfortable at room temperature. Always bundle up and stay warm. Use hot baths and showers.

Never drink water. Always get calories with your fluids.

Add butter or olive oil or peanut oil or cream cheese or regular cheese to everything you eat. Ketchup and mayo have calories; mustard does not so avoid it. If you have room for mustard you have room for ketchup.