It's a debate that has picked up in the past decade since Benjamin Spock, one of the world's best-known pediatricians, argued against milk and meat in children's diets.

Alongside quotes from specialists addressing obesity and diets for children, the ads described how McDonald's hamburgers are made of 100 percent real beef and cooked on a grill free of additional oil.

HARRIET WOROBEY, a childhood nutrition instructor, knows firsthand that children can be picky eaters, but even she was surprised by a preschooler last year who ate a mostly chocolate diet.