A review of 84 popular brands of cereal found that half of them pack more sugar in a one-cup serving than three Chips Ahoy cookies.

The Environmental Working Group's report says Kellogg's Honey Smacks is the worst offender. With nearly 56% sugar by weight, it has more sugar than a Twinkie (20 g and 18 g, respectively).

The report says three out of four cereals don't meet the voluntary guidelines proposed earlier this year by a U.S. congressional panel, which recommended the level of added sugar by weight not exceed 26%.

"Few parents would agree that a cereal that is one-quarter sugar by weight is the best that cereal makers can do for children," the report says.

More nutritious cereals - those with fewer ingredients, more fibre and no added sugars - are usually found on the top shelf of the cereal aisle, according to NYU nutrition professor and Marion Nestle. "They are harder to reach and not at eye level but often less expensive," Nestle said.

Here are the top 10 worst children's cereals, as determined by the EWG (based on percentage of sugar by weight):

Kellogg's Honey Smacks 55.6%
Post Golden Crisp 51.9%
Kellogg's Froot Loops Marshmallow 48.3%
Quaker Oats Cap'n Crunch's OOPS! All Berries 46.9%
Quaker Oats Cap'n Crunch Original 44.4%
Quaker Oats Oh!s 44.4%
Kellogg's Smorz 43.3%
Kellogg's Apple Jacks 42.9%
Quaker Oats Cap'n Crunch's Crunch Berries 42.3%
Kellogg's Froot Loops Original 41.4%

Find the complete list at ewg.org.

The EWG is a non-profit research group based in the U.S. that advocates on environmental and public health issues.