American kids are getting heavier. Too much extra weight puts kids， and adults， at risk for （A） d diseases. But a new study reveals some good news. Kids are showing signs of improvement in key markers of a potentially serious （1） c known as metabolic syndrome（代謝綜合征）. Better food choices likely triggered this change.

Metabolic syndrome is a group of symptoms that， taken together， mark people at high （B） r

of heart disease and diabetes（糖尿病）.

The syndrome can emerge when people eat too much sugar and don't get enough （C） e . Weight gain is the most obvious symptom. Fat people often suffer from high blood （D） p ， high blood sugar， high levels of bad fats and low levels of good cholesterol（膽固醇）.

Mark DeBoer is a doctor and （2） m researcher at the University of Virginia Health System in Charlottesville. He and his colleagues wanted to track signs of metabolic syndrome in U.S. teens. They took a look at the （3） h of 5117 adolescents（青少年） over a time period spanning 1999 to 2012. The information they gathered on these kids， aged 12 to 19， gives them a picture of the overall health of people throughout the United States.

Over the 13-year span studied， teens got increasingly heavier. At the same time， other aspects of teen health improved. In 2012， teens had lower levels of bad fats， than in 1999. They also had higher levels of good cholesterol. This likely means that there is a slight （4） d in the risk of future disease in this age group.

What changed over the studied （E） p ？ Teens in the later years were eating less sugary food. They also ate more foods with unsaturated（不飽和的）fat such as olive oil and tuna fish. DeBoer hopes that these （5） r mean that teens and their families are getting the message that foods with extra sugar and fat， such as soft drinks and pizza， can be bad for us.