A study finds that adolescents are starting to make better food choices, but we shouldn’t be so quick to credit the dietary guidelines.
Lately, the news about children and obesity hasn’t been good. That’s because the numbers have been trending in the wrong direction; for years, obesity rates have inched upward, and while they haven’t yet started to drop, they have begun to plateau. But other signs of health trouble, including diabetes, hypertension and heart disease, are also on the rise.
Yet in a study reported in the journal Pediatrics, researchers led by Dr. Marc DeBoer, associate professor of pediatrics at the University of Virginia, found encouraging news about some of these obesity-related health conditions. They analyzed data involving about 5,000 teens for signs of metabolic syndrome, a condition that increases risk of heart disease and includes obesity, high blood sugar, high levels of triglycerides (which mostly come from starches and carbohydrates), high blood pressure and low levels of the good cholesterol HDL. Overall, DeBoer found that severity of metabolic syndrome—or how deeply entrenched these risk factors were for the teens—declined between 1999 and 2012, even while their BMI, a measure of height and weight, increased.
The decline in metabolic syndrome could be an encouraging trend for this generation of teens as they become adults. Addressing factors like high blood pressure, cholesterol and weight can significantly lower the risk of heart disease and diabetes later in life.
When the scientists dissected the data more carefully, they found that the decrease in metabolic syndrome could be traced mostly to rises in HDL levels and drops in triglycerides. But does that mean that teens are eating less red and processed meats, which contain lots of saturated fat, and adding more fish and vegetables to their diet, which are high in the heart-healthier HDLs? Are their lower triglyceride levels due to cutting out processed and refined foods, like chips, that are high in carbohydrates?
Maybe, says DeBoer. “There was a consistent drop in the total number of calories consumed among adolescents,” he says. “And there was a consistent drop in the percentage of calories consumed that were carbohydrates, and an increase in the percentage of calories consumed that were from unsaturated fat. All of this is in the direction of recommendations from dietitians and shows that adolescents are starting to move in the right direction of consuming fewer calories, less carbohydrates and more unsaturated fat,” he says.
But before you think that teens have suddenly become docile students of nutritional information, it’s worth noting that the study still doesn’t directly prove that changes in dietary advice in the 2000s have definitely changed teen eating habits. DeBoer notes, for example, that in that same time period, adolescents (and adults) have become more sedentary, so it’s not surprising that they might be consuming fewer calories overall since they aren’t as active. That could explain why teens are eating fewer calories but their BMIs are still climbing upward. The researchers tried to see if exercise levels had any correlation to the metabolic syndrome measures, but the teens were only asked about physical activity during the later years of the study. With the data he did have, DeBoer didn’t see a significant relationship between minutes spent exercising and metabolic syndrome.
But while the government’s concerted effort to promote healthier eating habits by encouraging people to eat more plants, vegetables and fish may not be entirely perfect, it could be having some effect on improving the diets of young people, he says. “I would like to use the data to empower teenagers to tell them this study suggests that lifestyle changes you can make will help your metabolic syndrome severity,” he says. “I hope this motivates adolescents toward a healthier lifestyle.”
February 9, 2016
By Alice Park. Photo: Danny Kim