Q: My son is 13, and I want him to have a cellphone, but I'm not sure if he's mature enough to handle the responsibility. Any suggestions? -- Richard B., Columbus, Ohio

A: Cellphones are so powerful that kids need guidelines to avoid what we call the Digital Deficit -- that's being disconnected (from people, including parents), depressed and disrespectful. Fortunately, you now have an opportunity to protect your child's health, while you teach him etiquette. That will put you in the vanguard -- only 20 percent of parents set boundaries or offer advice on conduct.

Why is it important to do that? Kids are happier when they're not always on call. Many teens wake up during the night to receive texts, and sleep disruption causes everything from poor grades to pimples. The heaviest media users (kids connected to cells, TV and computers 16 hours a day!) are more apt to fail at school, be blue and fight with parents. Plus, teaching cell-etiquette (no talking on elevators, not within 10 feet of someone inside and never on public transportation) helps kids become aware of their effect on others, and that makes people respond more positively to them.

So write up a contract that spells out these guidelines: No cellphones in school, in the bedroom after lights out, and no texting while engaged in conversations or at the dinner table. Also, make it clear he's not to post photos of anyone online without permission. Plus, you'll check downloads for inappropriate material. And he has to answer your calls (unless he's in school or, a few years from now, driving).

Parents need to follow some guidelines, too: When children talk to parents on the cell they feel they're getting about 50 percent of the attention they'd get face to face. So, next time you think about disciplining you child via the cell, try this phrase: "We're not going to talk about this over the phone. We'll sit down and discuss this face to face when we're home."

Q: I just got a job in a retail store, and I'm stuck all day with nothing but mall food to eat. Help! Are there any good choices? -- Frieda J., Moline, Ill.

A: Bravo for thinking about it before you've made your RealAge much older and added inches to your waistline. The best choice is to bring food from home that's packed with the nutrients and fiber you need every day. Remember: no food felons (saturated and trans fats, added sugar, added syrups or any grain that isn't 100 percent whole). Bring veggie and turkey burgers, grilled fish and salads with a splash of olive oil (it liberates the salad's nutrients!) and balsamic vinegar. Pack snacks, too -- like walnuts and apples -- to help you through that 4 p.m. slump.

And just so you know what's out there, the folks at the Center for Science in the Public Interest researched the worst and best mall food options. The King of Catastrophe: Cheese fries with ranch dressing: 3,010 calories (almost two days' worth!); 217 grams of total fat with 91 grams of saturated and trans fat. A stuffed potato skin and sour cream delivers 1,260 calories; 95 grams of total fat with 48 grams of saturated and trans fats. These choices damage your heart, raise your cancer risk, wrinkle your skin and add years to your RealAge.

The good guys, according to the Center, are sandwiches with lean protein (turkey, chicken), veggies and mustard; Mickey D's fruit n' yogurt parfait with granola (380 calories and 5 grams of fat, with 2 grams of saturated fat), or a chicken souvlaki with rice (about 290 calories and 10 grams of fat with less than 3 grams of saturated fats).

Another tip to turn your mall life into a life-affirming experience: Mall walk, and get your 10,000 steps a day! On every break, walk the length of the mall and back (or more). After work, take a victory lap for a job well done!

Mehmet Oz, M.D. is host of "The Dr. Oz Show," and Mike Roizen, M.D. is Chief Medical Officer at the Cleveland Clinic Wellness Institute. Submit your health questions at www.doctoroz.com.