Overweight children may be incapable of running laps, jumping rope or playing soccer.
But they probably will shine at an activity previously thought to be inappropriate, even dangerous, for kids - strength training.
"You can't put these kids on a treadmill for 30 minutes and have them huffing and puffing and sweating," said Debi Pillarella, the 2004 fitness director of the year for the American Council on Exercise.
They are stronger than and can outlift any of their lesser counterparts.
The 17-year-old Phoenix boy started weight training in October at the Lincoln Family Phoenix Downtown YMCA.
He lifts weights four days a week after school under the supervision of J.R. Nelson, his physical education teacher at Genesis Academy.
"When I checked my weight on the scale, and I reached the high point, I was just thinking, 'No more,' " said Esteban, who weighs 350 pounds.
The teen said his upper body is gaining muscle, his stamina is improved and he likes the slimmer face that looks back at him in the mirror.
Free weights, body weight, machines and devices such as elastic bands and medicine balls provide the resistance.
Exercises include push-ups and pull-ups, biceps curls and leg extensions.
Two long-held misconceptions about strength training are that it may stunt a child's growth and that it should be prohibited in kids 11 and younger.
The benefits include improvements in muscular fitness, strength of bones, body composition, motor fitness performance and injury resistance.
It also may enhance self-esteem, mental discipline and the socialization of participants, both boys and girls.
During an eight-week strength-training class, the average youth adds 3 pounds of muscle, which equates to about 105 additional calories burned daily, said Westcott.