Margo G. Wootan, nutrition policy director at the Center for Science in the Public Interest (CSPI), said McDonald's agreed to drop soda and sugary drinks from Happy Meal menus last year, and 100 U.S. and local health organizations along with nutritional experts said in a letter to Wendy's, Burger King and 21 other restaurant chains that they too should remove the items from their children's menus.

Subway, Chipotle, Arby's and Panera already exclude sugary drinks from kids' meals.

"With 1-in-3 children overweight or obese in the U.S., it no longer makes sense to include sugary beverages in restaurant meals for young children," the letter said.

The groups quoted research published in The Lancet that found drinking just one additional sugary drink every day increases a child's chances of becoming obese by 60%, Wootan said.

Besides CSPI, the letters to the restaurant chains were signed by the Academy of Nutrition and Dietetics, the American Cancer Society, the American Diabetes Association, The California Endowment, the Consumer Federation of America, MomsRising.org and the National Council of La Raza.

"Parents face an enormous uphill battle when it comes to teaching their kids about nutrition and feeding them a healthy diet," said Kristin Rowe-Finkbeiner, executive director and chief executive officer of MomsRising.org.

"Restaurant chains that make a sugar drink the default drink make matters so much worse. It's time for Wendy's, Burger King, Chick-fil-A and Applebee's to follow McDonald's lead."