Physiologists tell us that approximately 3500 calories equal on pound of fat.It doesn't matter what type of food is eaten-nutritious food or "junk" -it all contains calories,and they all count. So if 100 calories remains unburned at the end each day for 35 days, the body will gain one pound of fat. By the end of this year,the body will have gained 10 pounds at the rate. This is the cumulative nature of weight gain.