ok walking burns 8 calories a minute at a reasonable pace. i found biking helped me loose weight . i am unsure how water helps but from experience i know it does. u need to burn more calories than you take in. but dont over do it. when you sleep you generally burn 450 calories so this is generally your lunch, if you walk for 30 minutes at a fast pace you can burn up to 240 calories. i found doing 3-4 miles a day on an exercise bike burns on average 130 calories and takes no more than 15 minutes to do on an average speed. going on a normal bike you can burn more for longer without realising. on average i bike 7 miles on my normal bike and it takes me 25 miles