Introduction: The National "Keep Fit" Programme is aimed at educating school children and their families so as to achieve sustainable development of pro-healthy eating habits through promoting an active lifestyle and balanced diet. The purpose of this study was to establish the relationships between mealtime rates, self-assessment of weight and measurable body mass index (BMI), estimated slimming rates and undertaken physical activity for junior high school and high school pupils along with university students in Poland, taking into account gender, age, place of residence and whether they took part in the "Keep Fit" programme. Material and methods: Subjects were 13,537 youngsters aged 12-18 years randomly selected in 2011. Of those, girls and boys not participating in the programme (non-participants) numbered respectively 6,535 (89.42%) and 5,328 (85.54%), whilst girls and boys who participated numbered respectively 773 (10.58%) and 901 (14.46%). For the junior high school and high school pupils, the research tool was a questionnaire developed by the Chief Sanitary Inspectorate, based on one previously used in a GSHS study. Students were however surveyed by electronic means, using forms available on a specific website of the Institute of Agricultural Medicine. Data analysis was performed by the STATISTICA 10.0 programme. Significance was taken as p being not greater than 0.05. Results: Participating in the "Keep Fit" programme had a beneficial effect on the number of mealtimes as well as the desire to maintain current body weights. There was no association/agreement between selfassessment of weight and the measurable BMI. Mostly it was male students participating in the "Keep Fit" programme who demonstrated higher weekly levels of physical activity compared to those not participating. Conclusions: The results suggest that the national "Keep Fit" programme had beneficial effects on shaping attitudes and behaviour regarding proper nutrition and maintaining a physically active lifestyle. These subjects showed an increased health awareness reflecting the effectiveness of the programme and the need for its continuation in subsequent years of school education.