Introduction:
Life style is one of the most important factors affecting health. Nutrition, physical activity and body mass control are life style-related issues considered as important determinants of health.

Aim of the study:
Assessment of health- and nutrition-related behaviour of pupils attending sports schools in relation to their gender and body mass index

Material and Methods:
The study was conducted on children and adolescents attending sports schools, involving 193 students aged 10–18. A survey designed by the author, consisting of 52 closed questions, was used. In order to calculate BMI, body mass and height were measured. The results were subjected to statistical analysis using the SPSS Statistics 17.0PL software. A correlation analysis with Spearman›s rho coefficient and a non-parametric Mann–Whitney U test were used to assess statistical relationship between health- and nutrition-related behaviour on one hand, and gender and BMI on the other.

Results:
The study demonstrated a statistically significant negative correlation between BMI and the frequency of snacking between meals (r= -0.21; p=0.05), soft drinks consumption (r= -0.41; p<0.001) and coffee consumption (r= -0.23; p<0.05). At the same time, BMI correlated positively with the length of sleep in children (r=0.57; p<0.001).aa

Conclusions:
The study demonstrated differences in health- and nutrition-related behaviour between boys and girls only in relation to the frequency consumption of bakery products. Nutrition-related behaviour of boys and girls in the surveyed group was very similar. The study demonstrated that an increase in physical activity in the surveyed group had an impact on a more frequent consumption of such products as meat, fish, fruit and vegetables.