Does swimming help loose weight?

I'm probably gonna go swimming for 1-2 hours each day doing laps. will it build muscles or help me loose fat? I also need skinner legs not musclier legs so would that help them get skinny?I have like 5 days to get into shape. i am doings an abs excerise so i dont need muscle from swimming, only burn fat. i am torturing myself with like 2 calorie foods. right now im eating a mix of cucumber, cabbage, carrot raw and nothing for a dressing. will swimming help? or should i look for other options?