In street clothes - roomy pink sweats or skimpy tank tops revealing broad, brown swimmers' shoulders - the teen blends in with her friends, a fresh-faced, robust-looking All-American girl.
That is the problem.
Like nearly one-third of American teens, Paris Woods is overweight. Her doctor worries her weight will creep up into the obesity range. One out of four black girls her age is obese.
The more than 11 million U.S. teens who are overweight or obese face an increased risk for diseases once confined to adults, like diabetes, artery damage and liver trouble. Those problems along with high blood pressure and high cholesterol are showing up increasingly in children.
Paris' pediatrician urged her to participate in an intensive experiment. The goal? To see if a yearlong program of weekly sessions with a nutritionist, exercise trainer and doctor, all preaching major lifestyle changes, could keep the 14-year-old from becoming obese.
It is the kind of intensive help that the influential U.S. Preventive Services Task Force says can work for teens.
Through successes, setbacks and even a bout with swine flu, Paris tried sticking with it. Skipped sessions stretched the program from 12 months into 20, but she did not quit.
Did it work? Stay tuned - her experience is a reflection of many families' struggles with obesity.
During Paris' endeavour:
Burger King introduced a 1,360-calorie triple Whopper sandwich; McDonald's profit climbed to $4.55 billion; and KFC introduced its Kentucky Grilled Chicken "for health-conscious customers."
Torrid, a nationwide chain of clothes for plus-size teen girls, opened its 156th store, up from six in 2001.
First Lady Michelle Obama - who grew up a few miles from Paris Woods' Chicago home - made fighting childhood obesity her pet project. "We have a chance to change the fate of the next generation if we get on it," she said recently.
The options in Paris' middle-class mostly black South Side neighbourhood are limited to a bounty of fast food. Paris has a taste for fried chicken, bacon cheeseburgers and Snickers bars, and sometimes little willpower. Swimming helps her fight that. The sport has been a passion since she was a little girl.
Her parents, Dinah and Parris Woods, wanted their three daughters to be active, to keep them busy and out of trouble. "You can't just do nothing," says Dinah, 47, a former fitness instructor.
In Paris' tween years, her weight started to creep up. She developed early and classmates made fun of her blossoming bust and swimmers' shoulders.
"They started calling me fat," Paris says softly. It made her very self-conscious.
So she wears two suits to swim. They are a drag on her swimming times, but help camouflage her curves.
Pulling on a blue swim cap and stretching goggles tight over her dark eyes, Paris shallow-dives into the pool where her club team practices.
With smooth, strong strokes, she glides effortlessly through the water, where no one comments on her size or tells her to watch what she eats. In the water, she says, "I stay calm. It takes all the stress away."
Paris' two college-age sisters ballooned into obesity in their teens. The family's pediatrician, Dr. Cathy Joyce, says that often happens - teens put on weight, go off to college, and come back obese.
So she asked Paris to join an obesity prevention study at Chicago's Rush University Medical Center. Because shedding weight is tough if the people in charge of filling the fridge are not on board, parents must enroll, too. Paris' parents also are overweight and have borderline high blood pressure. They readily signed up.
That was unusual. Joyce has had a hard time recruiting. Her goal is 50 patients; she has only 31. Some parents are not willing to change the family's lifestyle; others do not think their overweight kids are fat.
Joyce says parents often do not notice until teens are very obese, 50 pounds or so too much.
"Reality shows like 'The Biggest Loser' definitely have not helped," she said. They have skewed the public's perception of what overweight looks like, featuring people who are dangerously obese. The show's 2010 cast, including a 526-pound Chicago-area DJ, is its heaviest ever.
At 5 feet 4 inches and 158 pounds, Paris started the program about 20 pounds overweight. That was April 2008, just before her 15th birthday.
One of Paris' sisters had become a vegetarian, so the family decided to do the same. The hospital program does not require a specific diet but recommends healthy grains and lots of fruits and vegetables while avoiding unhealthy fats. Patients also are taught to read food labels and to eat three meals a day.
The idea is to choose a lifelong healthy way of eating.
It was all new to the Woodses, a tight-knit, busy family who used to skip breakfast and snack on the run.
Paris' mom likes to cook and the new regime lets her experiment with tofu, nuts and soy cheese. It also means shunning old family favourites, including ham and macaroni and cheese.
Their diet sometimes requires a trip to Whole Foods eight miles from home, and it is costlier, but Dinah Woods says she would prefer paying now, rather than later with her health.
The change was drastic, but also seemed exciting. Paris loved the avocado sandwiches and veggie burgers her mom packed for lunch, even if some friends turned up their noses.
At their weekly group sessions at Dr. Joyce's office, the Woods family weighs in and gets eating tips and encouragement from a nutritionist.
In the waiting room, there are half-hour workout sessions. Trainer Scott Mathews leads kids and parents through lunges, sit-ups, leg lifts and other exercises they are urged to do at home.
The Woodses usually come on Wednesday evenings. It is not a perfect time - everyone is tired after school and work. Dinah is a sales counsellor and Parris, 46, a technician for hospital TV systems, attends night school. But they all gamely roll out exercise mats and dive in.
A session in late 2008 had Paris on her back, pedaling her legs and breathing hard. She rolls her eyes when Mathews asks if she is getting tired.
"I know you're tired. You just have to push when you're tired," he says.
Besides swimming most days, Paris likes to run with her two dogs, and tries to walk, instead of ride, when she can. Her parents walk a few miles several mornings before work. It was relatively easy to stick to the regimen during that first summer and fall.
By October, Paris' weight was down 8 pounds, to 150, and she had lost 3 inches from her waist. Her parents also have shed pounds, and all three say they have more energy.
Paris has lost her taste for meat. "I'm just like, ew, it's so nasty," she says
In November, the Thanksgiving feast was the first big test. No turkey, ham, biscuits, cheesecake or chocolate cake like Dinah used to make. Instead, Paris says, it is "tofu everything," plus lots of vegetables and wheat rolls. Could Dinah's lemon cake made with egg substitute possibly taste as good as her traditional desserts? "No, not really," Paris says laughing, "but I had to eat something."
The Woodses were nervous before the next weigh-in, but the scale showed good news: No one had gained weight.
By mid-December, Paris felt really proud. She bought new pants and belts. And looking in the mirror, she says, "I don't see a face around fat. I just see, like, my bone structure ... my features in my face" are more visible.
It is a face full of youthful softness and a grown-up beauty in her sparkling eyes and arched eyebrows. Paris is starting to tell herself she looks pretty.
Still hovering around 150 pounds, she hoped to weigh 140 pounds by her 16th birthday, April 13 last year. "If I reach that, I'll be pretty happy," she said. Her birthday would mark the end of the yearlong effort.
Chicago's 2008-09 winter was harsh, snowy and cold. Paris felt little motivation to venture outside to exercise. It was dark when she got home from school and homework kept her busy until bedtime.
Her friends alternated between encouragement and saying she is wasting her time. Her dad said Paris "is fine as long as she's at home. She pretty much sticks to the diet. When she's with friends, they go out to burger places. She struggles with that a bit."
At school lunch, friends reach over and grab bites of her veggie sandwiches, and Paris thinks it's unfair that their food is off-limits. Sometimes she takes a few bites, anyway.
By April 2009, it was clear that Paris would miss her birthday goal. In fact, she had put on about 5 pounds. Wearing a tight magenta tank top accentuating her tummy bulge, she says, "I just want my stomach a little flatter."
But she acknowledges "getting a little tired" of the food.
Since they began a year ago, the family has missed several sessions because of busy schedules, but they have vowed to complete the program and are allowed to continue for several more months.
Then Paris was sidelined with swine flu. She skipped a few more program sessions, and then a few more because of training for a lifeguard job, but also loses a few pounds.
During the summer, lifeguarding interferes. Instead of swimming, it means long hours sitting in a perch, watching other children swim. By the time she gets home, she's too tired to work out.
The fast food at the pool proves tempting. She pushes the diet out of her mind, and pigs out with her friends at the pool on tacos, burgers and gyros.
There was no place to refrigerate the lunches her mom packed, sometimes boring leftover tofu burgers from the previous night's dinner.
She skipped several doctor sessions, because of schedule conflicts and because she knew that she was gaining weight. She had never been so disappointed in herself, and considers quitting for good.
Looking back, she says, "It was horrible. I was like, I couldn't go back because I gained so much weight."
But she returned to the medical center when the summer job was over.
Late 2009 was stressful for everyone. Dinah had to work long hours, arriving home too late to fix dinner. She and her husband still ate vegetarian. Paris did too, at home, but continued to eat fast-food away from home. Now a high school junior, she was stressing out over college admissions exams and much of her free time was spent studying for them.
When Thanksgiving arrived in late November, it was another tofu turkey day. But everyone fell off the wagon during a family vacation to Disney World after Christmas. Along with fresh seafood, there were funnel cakes, ice cream bars and cookies.
Finally, the Woodses' last program session arrives - Jan. 19, close to two years. Paris seems tense. You can almost hear a drum-roll as she steps onto the scale: 170.6 pounds.
That is 12 pounds heavier than when she started. Her waist size is the same, 33 inches.
There are no tears, but she looks dejected and is thinking "failure."
Dr. Joyce does not see it that way. Disappointing, yes. But she has overweight patients who were not in the study who gained at least twice as much over the same time frame.
The success is that Paris did not become obese - she looks far from it - even though she was a mere four pounds away from that.
Paris' dad ended up a few pounds heavier too, but his waist shrank an inch. Her mom dropped 6 pounds and 5 waist inches.
Joyce says skipped sessions might have been a factor; continuous professional feedback is motivating although too costly to last indefinitely. A research grant paid for the Woodses to participate; otherwise the counseling and checkup sessions likely would have cost well over $4,000.
Paris Woods' results show what everyone knew at the start: Losing weight and keeping it off is tough, and life sometimes gets in the way.
Dr. Ned Calonge, chairman of the preventive services task force, which recently reported that comprehensive programs for children can work, said conquering the obesity epidemic also requires changing cultural norms: making healthy food more available than fast food and encouraging physical activity.
Joyce says it is too early to declare her program a failure or a success; some teens haven't finished the program and she'd like to track them afterward.
She says kids must realize it requires a lifestyle change, and that "it's not the McDonald's, it's not the Burger King that's pulling you in. You're choosing to go there."
Dinah Woods says her family learned that lesson, and more.
For her, it was the first time in a long time that she went an entire year without gaining weight.
Raised to think meat was required at every meal, Dinah says she learned "that it's OK to eat just vegetables for dinner," or even a peanut butter sandwich.
"The beauty of it all, that all of us learned from it, is the importance of our health, that we're in control," she said.
As for Paris? Despite her disappointment, she says the program changed her for the better.
She knows she has to control her eating and keep active; she even is thinking about training for a triathlon.
"I know what I'm supposed to do," she says. And she knows that if she works hard at it, every day, she can succeed.
"I believe I really can."