I am going to start a diet and stop drinking coke what else can help me lose weight?

Count your calories: Giving up soda is a great start as it has little nutritional value but is loaded with sodium and sugar. Choose foods with high nutritional value and watch the fat calories as fatty foods have 9 cal/gram while carbs and protein have about 4 cal/gram. People can say this and that about carbs versus fat versus protein. In the end it still amounts to how many calories consumed minus calories burned.