Experts have produced a "report card" on the activity levels and health of Scotland's children, grading 10 categories from a possible top "A" down to "F minus", with many failing to reach even a basic pass mark.
Three of the 10 categories (physical activity, sedentary behaviour and obesity) are awarded the lowest "F" or "F minus" grade, meaning the healthy living message in these categories is getting through to fewer than one in five children.
The Active Healthy Kids Scotland Report Card - the first of its kind in the country - suggests that levels of obesity among young people are at a record high.
Meanwhile according to the Scottish Health Survey, at least 16% of two to 15-year-olds were obese in 2011.
Citing the survey, the report card states: "Multiple data sources suggest that levels of obesity among children and adolescents are higher than at any time in our history. Obesity prevalence among children and adolescents has more than trebled since 1990, and obesity is more common among the more deprived."
The study also finds that only one in five adolescent boys (19%) and one in 10 girls (11%) aged between 11 and 15 meet the recommendation of doing moderate physical activity for at least 60 minutes a day.
Guidelines say that school-age children and adolescents should spend no more than two hours of their leisure time in front of screens, but the survey suggests three-quarters of 11 to 15-year-olds spend more than two hours a day watching TV (76%).
Beyond that, around three-quarters of boys (77%) and almost two-fifths of girls (37%) spend two hours a day on gaming.
Diet and the influence of relatives and peers also fare badly in the report card, both securing "D-minus" ratings.
Youngsters' sugar and saturated fat intake far exceeds recommended levels and just one in seven children eat the recommended five portions of fruit and vegetables per day (14%).
Statistics looked at for the study also show that almost half of adult men and a third of adult women do the recommended five lots of 30 minutes of exercise each week.
Conservative estimates show that, in 2011, two-thirds of adults were overweight or obese (64%) and just one-fifth ate five portions of fruit and vegetables per day (22%).
At the other end of the spectrum, the report card awarded "Bs" in the categories of community and the built environment, and to national policy.
"Physical activity and health is given great emphasis in national policy, strategy, and investment," the study said.
The report was produced by an expert group led by the University of Strathclyde.
John Reilly, professor of physical activity and public health science at the university, said: "This report card - Scotland's first of its kind - provides a critical, current and comprehensive assessment of the physical activity and health of Scotland's children and adolescents. The report card should be used as an advocacy tool and as the basis of public debate, policy discussion and change."
The plan is for an international report card to be published in May next year, so Scotland can be compared against other countries, he said.
Professor Geraldine McNeill, of the University of Aberdeen, a partner in the project, said: "The card is designed to be a one-stop shop for information on the major determinants of children's weight and provides benchmarks which will allow us to monitor progress in improving children's activity and diet in the future."
The study was funded by the Scottish Universities Insight Institute.