Despite parents' best intentions, children often develop less than ideal eating habits. The cheese and bread menu is quite common among kids, with pizza, grilled cheese, and macaroni and cheese being perinneal favourites. At the age of 12, it may be particularly difficult to change this diet and you are right to believe that having fights about food is to no one's advantage. However, there are some things you can try that may be successful for your child.
1) If there is any fruit, vegetable, or other nutritious food item that your child will eat, offer it often.
2) Try the stealth method. Puree vegetables in pasta sauce, offer carrot/zuchinni muffins, disguise fruit in smoothies, etc.
3) Invite your child to participate in the process of widening his food choices. Ask him what foods he'd consider trying. Take him grocery shopping. Involve him in menu planning.
If none of this is effective, fear not. Most children manage to thrive despite their poor diets. Some even grow up to develop excellent eating habits! Continue to maintain a positive mealtime environment and model good eating habits. Hopefully, this will just be a stage that he grows out of.
Brenna Leah Cashman, RNCP