Simply put, we gain 1 pound in weight when we consume an extra 3,500 calories over and above what our body uses in growth, metabolic activities and exercise. This does not have to be in one day! If we take in 100 extra calories a day for one year, we end up gaining nearly 10 pounds! And 100 calories is only a half a can of soda so you can see how easy it is for the pounds to pile on. Conversely, cutting out a half a can of soda each day will result in a 10 pound weight loss in a year. When children understand this, they see how small changes can make a big difference.