Although this seems surprising, cereal typically contains massive amounts of sugar, so it makes sense that eating it regularly could make a person gain weight. (progressivehealth.com)
You get a nice serving of calories but you also get massive amounts of sugar, oil, flour, fat, corn syrup. (themilitarydiet.com)
There's no fiber in it, no chewing resistance and nothing to stop you from downing massive amounts of sugar in a short amount of time. (healthline.com)