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Our bodies are conspiring against us.

Danica Lo
Updated May 24, 2017

Bad news, tweens: According to a recently study published in the International Journal of Diabetes, as a 15-year-old you're burning 500 calories less a day now than you were at age 10—and you'll have to wait until you're 16 for a calorie expenditure uptick. Worse yet, you're being slammed with media (and peer) pressure to participate in less healthy food choices. "Adolescents sitting around using their smartphones and iPads are being bombarded with junk food marketing—while using even fewer calories than we previously thought," Professor Simon Capewell, vice president of the Faculty of Public Health at the University of Exeter told the BBC. "We need much tougher regulation around the marketing of junk food to children—particularly on TV and online."

The study, which took place over ten years and included 279 participants, found that "energy used at rest was 25 percent lower in 15-year-olds compared with when they were 10," which explains why teen years are when lots of people pile on extra weight—weight that becomes harder to shake later on. According to the Centers for Disease Control (CDC), 18 percent of children in the United States aged 6 to 11 are obese—and 21 percent of teens aged 12 to 19 fall into the same category. What's really scary is that being an obese teenager drastically increases the probability of being obese as an adult—which comes along with an increased risk for a whole slew of obesity-related health problems.

"Children and adolescents who are obese are likely to be obese as adults, and are therefore more at risk for adult health problems such as heart disease, type 2 diabetes, stroke, several types of cancer, and osteoarthritis," the CDC warns. "One study showed that children who became obese as early as age 2 were more likely to be obese as adults."

It's disconcerting, then, that people naturally experience a decline in calorie expenditure around puberty. Experts recommend that schools, parents, friends, family, and community groups "play a particularly critical role by establishing a safe and supportive environment with policies and practice that support healthy behaviors."

In the last few years, the food industry has seen an increasing interest and awareness around school-age children's food-related activities and behavior—but we still have a long way to go. Remember how Jamie Oliver's Food Revolution went down in schools around the United States? Well, at least we'll always have YouTube.