About two years ago around Easter, Moises and Chelsea Sanchez were allowed to select all the sweets they wanted for the holiday from a dollar store – chocolate bunnies, bite-sized vanilla-filled chocolate eggs and marshmallow Peeps.

“We just ate them all in like a week,” Moises said.

At the time, after-school activities were limited to watching TV, working on the computer and playing video games. While Moises liked to indulge in Chinese food, Chelsea enjoyed pepperoni pizza.

A sedentary lifestyle and unhealthy eating habits are what led Moises and Chelsea to become overweight. Between 2005 and 2006, about 15 percent of 6- to 11-year-olds and 18 percent of 12- to 17-year-olds were overweight in the United States, according to a National Health and Nutrition Examination Survey. The number of obese children was just as high: Between 2007 and 2008, nearly 17 percent of 2- to 19-year-olds in the United States were obese, according to a National Health and Nutrition Examination Survey released in 2010.

A child is considered overweight when their body mass index is at or above the 85th percentile and lower than the 95th percentile. A child is considered obese when his or her body mass index is at or above the 95th percentile, according to the Centers for Disease Control and Prevention. These percentiles are age- and gender-specific.

At his heaviest, Moises, now 14, was about 170 pounds. Chelsea, now 12, was about 140 pounds. They were both around five feet three inches tall.

“Most of the time I would like to wear baggy clothes so it wouldn’t show my stomach. I was embarrassed by my weight,” Chelsea said.

“I’d always go like this,” she said, pulling her T-shirt over her stomach.

Last summer things began to change for the siblings. They joined a summer camp where instructors emphasized exercise, nutritional eating and a healthy lifestyle. At Miami-Dade County Parks, Recreation and Open Spaces Department’s Fit-to-Play camp, Moises lost 40 pounds and Chelsea lost 35.

Similar programs have sprung up throughout South Florida to reverse the rising tide of overweight and obese children. At the University of Miami Miller School of Medicine’s Crunchtime program, children take a one-on-one fitness class and learn about nutrition. In Broward, a group of about 25 kids work on their core strength twice a week at the Power ABS class at the David Posnack Jewish Community Center. And at Memorial Regional Hospital Fitness Center in Hollywood, children join an exercise class and, along with their parents, learn about nutritional eating.

“We need to intervene early as our kids start to gain weight,” said Dr. Will Charlton, a pediatric endocrinologist at Joe DiMaggio Children’s Hospital, part of the Memorial Healthcare System. “If we can get a hold of these kids earlier and make changes, then we can hopefully reverse this trend.”

Obesity in children can lead to the early onset of Type 2 diabetes. In the past five years the number of children with Type 2 diabetes has “skyrocketed,” Charlton said. This is a phenomenon that did not even exist 20 or 30 years ago.

In Type 2 diabetes, an overweight or obese person becomes resistant to insulin, the hormone that carries sugar from the blood to the cells. As a result, insulin does not work well and blood sugar spikes. The body is fooled into thinking that it needs more calories to function and a signal is sent to the brain, telling it to conserve calories.