Chapter 2.1, Problem 8E

“Fruit Juice May Be Fueling Pudgy Preschoolers, Study Says” is the title of an article that appeared in the San Luis Obispo Tribune (February 27, 2005). This article describes a study that found that for 3-and 4-year-olds, drinking something sweet once or twice a day doubled the risk of being seriously overweight one year later. The authors of the study state

Total energy may be a confounder if consumption of sweet drinks is a marker for other dietary factors associated with overweight (Pediatrics, November 2005).

Give an example of a dietary factor that might be one of the potentially confounding variables the study authors are worried about.