Even one pack of M&M's may be more than you should eat in a day, newly drafted guidelines from the World Health Organization suggest.

The WHO used to recommend that you get no more than 10% of your daily calories from sugar, but now they're considering lowering that to 5%. For an average, healthy adult, that would mean 25 grams, or about six teaspoons of sugar per day. (That's a little less than what you'd get from 10 Hershey's Kisses. A single can of Coke has 39 grams of sugar.)

A teaspoon of sugar in your coffee or a half cup of ice cream won't kill you — all things in moderation — but the average sugar intake in the U.S. is 22 teaspoons per person per day. That's almost four times as much as the WHO's new guidelines suggest is healthy.

People have been sounding warnings about the dangers of too much sugar for a long time. As early as 1957, John Yudkin, a professor of nutrition at Queen Elizabeth College in London, began arguing that when it came to heart disease and other chronic ailments, sugar — not fat — was the culprit.