Eating McDonald's french fries could affect more than just your waistline.
The fast food giant has acknowledged that the fries contain gluten -- wheat and dairy ingredients are used to flavor them. And those substances can cause allergic or other medical reactions in food-sensitive consumers.
Doctor Henry Fishman, a Washington, D-C, allergist, says these reactions can include weight loss and chronic diarrhea.
Fishman says while these allergies and sensitivities to glutens are quite rare, it's important that people who have them know if foods they eat contain the substance.