I have two children:
My daugher, age 14, eats mainly meat anyways. She never liked potatoes unless they are french fries and rice and such are just not liked at all. She eats a few veggies, spinach, broccoli, green beans, Cauliflower. Her problem is candy. She sneak money and buys candy or soda when she can. Sugar gives her headaches but she learning how to control them by not eating sugar but its so hard for her. She loves string cheese but she loves yogert (gogerts) as well. She is 40lbs overweight already.

My son, age 11, rarely eats meat unless its a McDonald hamburger with cheese, a hot dog, or ham (which is a little expensive as well as ribs that he loves) He mostly eats carbs.
He loves them all. I caught him this morning making his fourth bowl of oatmeal and he already had two large bagels. He likes jerky and cheese sticks. He is 30lbs overweight.

Both my kids are very addicted to carbs. Their emotions go way up if they go too long without carbs, plus their weights are too much. I don't want them going through what I have gone through. How do I get them to see the benifits of LCing besides example?