A good diet is crucial during adolescence because “it’s a time of such rapid growth and development,” says Casey Beeghly, a registered dietitian with Sentara Healthcare in Norfolk, Va. Some tips:

Explain nutrition on their terms. Teens might not care that unhealthy eating could contribute to problems such as high blood pressure or brittle bones years later. They do care about having clear skin, thick hair, a good body weight and more energy and brainpower.

Calcium is key. Teens need at least two daily servings of low-fat dairy such as milk, yogurt and cottage cheese to support bone growth. Other good sources are dark green vegetables, nuts and fortified cereals.

So is iron. The mineral helps build lean body mass, increase red blood cell production and, for girls, replace iron lost during menstruation. Iron-rich foods include lean red meats, chicken, fish, beans, broccoli, spinach and fortified whole grains.

Add in folic acid. This vitamin also helps build lean muscle, and girls need it to guard against birth defects in future pregnancies. Dark green vegetables, citrus fruits and fortified breads and cereals are good choices.

Boost fiber intake. Many teens aren’t great about eating fruits and vegetables. Keep encouraging those foods, along with whole-grain breads and cereals with at least three to five grams of fiber per serving.

Help them not skip meals. Up to a quarter of teens don’t eat breakfast every day. For easy-to-grab options, fill a basket with fruit, whole-grain granola bars or small bags of handmade trail mix (try Cheerios, cranberries, raisins and nuts).

Be realistic about fast food. Instead of forbidding it, educate teens on healthy swaps such as grilled chicken sandwiches for fried, mustard for mayonnaise, apple slices for fries or baked chips for regular.