A new report from Environmental Working Group says only 20 of the 84 popular cereals meet criteria for sugar, sodium and saturated and trans fat.
The report also says some of the cereals even have more sugar than three chocolate chip cookies or one Twinkie.
Kellogg's Honey Smacks is the top offender with 5 teaspoons of sugar per cup. That amounts to nearly 56 percent sugar by weight.
Also on the sugary list are Post Golden Crisp, Quaker Oats Cap'n Crunch Original, Quaker Oats Oh!s and Quaker Oats Cap'n Crunch's OOPS! All Berries.
10 worst children's cereals (based on percent sugar by weight)
1. Kellogg's Honey Smacks (55.6%)
2. Post Golden Crisp (51.9%)
3. Kellogg's Froot Loops Marshmallow (48.3%)
4. Quaker Oats Cap'n Crunch's OOPS! All Berries (46.9%)
5. Quaker Oats Cap'n Crunch Original (44.4%)
6. Quaker Oats Oh!s (44.4%)
7. Kellogg's Smorz (43.3%)
8. Kellogg's Apple Jacks (42.9%)
9. Quaker Oats Cap'n Crunch's Crunch Berries (42.3%)
10. Kellogg's Froot Loops Original (41.4%)