As far back as middle school or even grade school, it was relatively easy to determine which students would grow up to make something of themselves and which would not. A person from my 4th grade class who we all knew was trouble was recently sentenced to nine years in jail for stealing a state vehicle. It's doubtful that anybody is surprised.

Though there clearly are exceptions, the general rule is that good, well behaved students have a better chance at success than bad, poorly behaved students. But success isn't the only thing that matters. Health does, too, and new data on high school students from the CDC shows a consistent link between a student's grades and healthy or unhealthy behaviors.

Does Unhealthy Behavior Cause Bad Grades?

It's important to note that this study, which is cross-sectional in nature, does not determine causation. It cannot be declared, for instance, that healthy behaviors (e.g., eating breakfast and exercising) cause a student to get good grades. Conversely, it cannot be concluded that unhealthy behaviors (e.g., smoking pot and engaging in unprotected sex) cause bad grades. It is reasonable to suspect, however, that grades and lifestyle choices reinforce one another.

Additionally, a third factor is probably the best explanation: Responsibility. Responsible students get good grades and live a healthy lifestyle; irresponsible students get bad grades and make poor lifestyle choices. (Responsibility, in turn, is affected by home life, socioeconomic status, and culture, among other factors.)

With that caveat in mind, some of the behavioral patterns among good and bad students is striking. (See chart below, which is adapted from CDC data. The CDC assessed 30 different behaviors, but only the most intriguing ones are shown below. Note that confidence intervals have been omitted for simplification.)

Students who make mostly A's are nearly 2.5 times more likely to eat breakfast every day than students who make mostly D's/F's. They are also more likely to be physically active. On the flip side, students who make mostly D's/F's are more likely to watch too much TV, drink, smoke pot, and have sex. They are nearly four times more likely to attempt suicide than A students.

What is also striking is the clear gradient that occurs for each behavior: A students make better choices than B students, B students make better choices than C students, and C students make better choices than D/F students.

The takeaway message is that a high school student who makes bad grades is not only setting himself up for professional failure; he is also likely making lifestyle choices that will put him on a course to bad health.

Source: Rasberry CN, Tiu GF, Kann L, et al. "Health-Related Behaviors and Academic Achievement Among High School Students — United States, 2015." MMWR 66 (35): 921-927. Published: 8-Sept-2017. DOI: 10.15585/mmwr.mm6635a1.