The only interesting thing I found was this: 'Serving sizes are regulated by the Food and Drug Administration, and can change if a cereal’s density changes. It

The only interesting thing I found was this: 'Serving sizes are regulated by the Food and Drug Administration, and can change if a cereal’s density changes. It appears that at some point in the last 10 or 15 years, General Mills tweaked the ingredients of Honey Nut Cheerios in a way that lowered the overall weight per serving, which had the effect of helping lower the stated sugar content.' I wasn't aware that the FDA regulated serving sizes, or that they could change based on a recipe change. Will make me double check before and after stats on any product that claims "now X% less sugar/fat/etc".