i read this somewhere the other day and found it very interesting: australian's put on an average of 1kg/year after the age of 25 (or something, i can't remember it precisely).
1 kg = 7700calories.
7700calories / 365 days = 21.1 calories per day
so, on average, each australian is in calorie surplus by 21.1 calories per day. that's like 33mL of milk or 6g of sugar or 8g of white bread or 3g of butter every day for the rest of their lives... the power of very small amounts of force over time.