Some of the most popular brand cereals contain more sugar in a one-cup serving than a Hostess Twinkie or three Chips Ahoy cookies, according to a new study by the independent Environmental Working Group.

The EWG's analysis of 84 brands, including some of the most popular among children, found that only about 21 actually meet the government's voluntary guideline of no more than 26 percent added sugar by weight.

Among those with the most added sugar are Kellogg's Honey Smacks, with nearly 56 percent, followed by Post Golden Crisps with 51.9 percent, and Kellogg's Fruit Loops Marshmallow with 48.3 percent. Researchers said the figures amount to nearly five teaspoons of sugar on average per one cup serving, which doesn't even come close to the size of the cereal bowl that most kids use every morning at breakfast.

"The fact that a children's breakfast cereal is 56 percent sugar by weight -- and many others are not far behind -- should cause national outrage," said health expert Dr. Andrew Weil in a press release issued by the EWG. Weil added, "Fifty years of nutrition research has confirmed that sugar is actually the single most health-destructive component of the standard American diet."

In response to the childhood obesity epidemic, Congress set up the Interagency Working Group on Food Marketed to Children to help push back against advertising directed at children by food companies designed to increase the popularity of certain breakfast cereals. As a result, the government group recommended to Congress that no more than 26 percent of added sugar by weight be established as a voluntary standard for companies to follow. But most haven’t and the advertising directed at kids has gotten even more aggressive.

"The cereals on the EWG highest-sugar list are among the most profitable for their makers, who back up their investment with advertising budgets of $20 million a year or more," said New York University nutrition professor Marion Nestle. "No public health agency has anywhere near the education budget equivalent to that spent on a single cereal. Kids should not be eating sugar for breakfast. They should be eating real food."

Officials at the Centers for Disease Control and Prevention say that about a fifth of American kids are obese and that the rate of obesity among children has tripled over the past 30 years. Studies suggest that much of the problem has to do with the amount of sugar kids consume, which also causes other health issues, such as diabetes and attention disorders.