I don't see how that follows. The amount of sugar produced is roughly equal to the demand for sugar -- and as sugar is eaten it immediately decomposes and cease

I don't see how that follows. The amount of sugar produced is roughly equal to the demand for sugar -- and as sugar is eaten it immediately decomposes and ceases to be sugar. So there is a fixed surplus of sugar in the world, and that's the only relevant amount. Production and consumption cancel each other out. Assuming the average person weighs 50kg, there has to be a 5 year surplus in order for the surplus per person to be heavier than the person. I consider it highly unlikely we stockpile a 5 year supply of sugar (200+ billion kg) -- especially since there is no incentive to do so.