Sugary drinks, fried snacks

In Qian's village, school lunches — subsidized under China's national Rural Nutrition Improvement Program — typically include rice, vegetables and modest portions of meat.

But once classes end, children spill into narrow village lanes lined with family-run shops. Refrigerators hum with brightly colored sodas. Plastic jars hold fried snacks dusted with chili powder.

"I get hungry easily," Qian said. "After basketball, I always want something cold and sweet to drink."

Qian Guoping, who runs one of the small stores near the school gate, said sugary drinks are among her best-selling items. "They're not expensive — 3 yuan ($0.15) to 5 yuan. After sports, the kids come in groups."

Some parents wonder "if exercise is supposed to keep children healthy, why do some active kids still gain abdominal fat?"

Gu Zhongyi, a nutritionist and science communicator, said the answer often lies in what happens after the exercise ends.

"Physical activity can stimulate appetite and thirst," he said. "If the available options are high-sugar drinks or fried snacks, children may easily consume more calories than they burned."

A child might burn 150 to 200 calories during half an hour of running, he said. A single bottle of sweetened soda can contain roughly the same amount.

Because liquid calories provide little sense of fullness, children may drink them quickly without reducing their overall food intake.

Nutritional scientists refer to this dynamic as compensatory eating, increased calorie consumption following physical exertion. "Exercise is beneficial," Gu said. "But it cannot cancel out a high-sugar diet."