In an age of constant dieting and obsessions about body size, it's essential to share positive messages about healthy eating.

As a teen, I ran out the door without eating breakfast each day, and I lived on doughnuts and gravy-topped french fries. Looking back, it's amazing I didn't fall asleep every afternoon or develop scurvy from a lack of vitamin C. Sadly, fast-food diets and sugar highs are not uncommon for teenagers.

"On the whole, people will eat more sugar in their teen years than at any other time in their lives,” says Haley Barton, a family nutritionist in Vancouver.

According to the Centers for Disease Control and Prevention, almost 40 per cent of teens eat fruits and vegetables less than once a day. Here's how you can swap some fruit for those fries and improve your teen's diet.

Healthy Eating Starts at Home

Preteens and teens forge their own paths, but when it comes to healthy eating, they are likely to follow their parents' lead. A study published in Preventive Medicine found that a healthy home environment is essential for determining how children will eat both now and in the future.

Additional research from UCLA Center for Health Policy Research found that teenagers whose parents eat five servings of fruits and vegetables a day are 16 per cent more likely to do the same when compared with teens whose parents eat less fruits and veggies. The research also found that kids whose parents frequently drink pop are 40 per cent more likely to drink pop daily themselves.

"Stock your cupboards with the foods you want your kids to eat,” Barton says.

You can't control what your adolescent eats when she's out of the house, so focus on what you can control and keep chips, cookies and soda out of your home.

Sitting down to eat as a family is also key. A study in the Journal of Epidemiology & Community Health found that eating meals together with their family dramatically increases children's consumption of fruits and vegetables.

According to a study of 2,383 kids, those who always ate family meals together at a table consumed 1.5 more servings of fruits and vegetables a day than those who never ate with their families. Can't make dinner together every night? Don't worry. Even kids from families who reported eating together only once or twice a week consumed 1.2 more servings daily than those from families that never did.

Focus On What You Can Change

"Use your influence where you have it,” Barton says.

Serve healthy food for breakfast and dinner, and accept that you don't have much control over lunch. Speak to your children about reducing sugar, but talk in terms of moderation rather than trying to ban candy and sweets altogether. And, if you can only do one thing, get your kids off pop! Drinking empty calories through these sugary beverages is one of the worst habits your teen can pick up.

"Encourage them to drink water for thirst,” says Stefanie Senior, a registered dietician and nutritionist in Toronto. If you focus on one or two important things rather than trying to entirely change the way your child eats, you'll be more likely to succeed.

Speak Her Language

Teaching the importance of good nutrition is vital, but taking a mom-is-watching approach can backfire.

"Find the right mix of being honest and letting your child know you're thinking of them,” Barton says.

Highlight the positives while avoiding speaking negatively about their eating habits.

According to a 2010 study based in the United States, an average teenage girl sends and receives about 135 texts per day, so it makes sense to send nutritional notes via text. (Teen boys get into the texting frenzy as well, with an average of 85 daily texts.)

A 2013 study published in the Journal of Nutrition Education and Behavior found that one of the best ways to influence nutrition knowledge, attitudes and behaviours is through health promotion campaigns using texting.

Youth tend to follow people they look up to, so when you see a magazine article that talks about how a star like Aimee Teegarden, from TV's "Friday Night Lights” eats healthily as a vegetarian, text the link to your daughter.

"If you're out shopping, try texting: ‘Just bought the best local apples. Make sure you get some before your dad eats them all,' ” Barton says.

It's a great way to plant the seed of healthy eating without seeming too controlling. If your teen is looking for more information, send her to www.beinggirl.com/