What are the first images that come to mind when you think about  summer vacation? Chances are, you picture children running around outside – using their lazy days out of school to swim, play pickup games of softball or soccer, ride bikes, or learn a new sport at camp. You also might imagine young people eating more healthy meals and enjoying the seasonal bounty of fruits and vegetables. Obesity is probably not something that comes to mind when you ponder summer.

Yet an emerging body of research shows that the summer break from school poses significant challenges to children’s health as well as their educational achievement, contributing to the twin problems of obesity and food insecurity for young people and affecting their ability to return to school ready to learn. Here are a few of those findings:

• A recent study from the University of California, Irvine found that adolescents who were regularly in the care of their parents during the summer without participating in organized activities showed the greatest risk of obesity. Researchers at Tufts University found similar patterns in a pilot study involving younger children.

• A study from the University of Wisconsin Children’s Hospital in Madison found that positive changes from a school-year physical fitness program were lost during the summer break.

• Another group of researchers found that children gained BMI two to three times faster during the summer as compared to the school year, and that children already at higher risk of being overweight were particularly susceptible to excessive BMI gain during summer.

When the school doors close, most children who qualify for federally funded school meals also lose access to those meals during the summer.

Studies also consistently show a relationship between children being overweight and having poorer levels of academic achievement. Conversely, physical activity has been shown to improve cognitional, mental, and emotional health, and connectedness with peers and teachers. Most children already lose two months of math computational skills during summer break, and low-income children lose an additional two to three months of reading skills.

The good news is that high-quality, low-cost or free summer learning programs can tackle all of these problems at once - providing summer meals and engaging, fun activities for body and mind, as well as academic practice that allows children to move confidently ahead when the school year begins.

A new report, “Healthy Summers for Kids: Turning Risk Into Opportunity,” summarizes both the challenges to summer health for youth and promising practices to improve health around the country. You can plan to do your part this summer to make sure the children you care about stay active and healthy. Limit the screen time. Pull out the soccer ball and the swimming gear. Take the family to the farmers’ markets, and have the kids add up the bill to practice math while they try new foods. Take some time to read, and make sure to remember that summer should be a season for learning – and health.

Gary Huggins is the chief executive officer of the National Summer Learning Association.

All statements and opinions expressed on this blog are those of the individual contributors, and not of the Bill & Melinda Gates Foundation or NBC News.