This diploma thesis deals with changes in body weight during the year depending on circadian typology of adolescent girls. The theoretical part focuses on the specification of the development period of adolescence, body weight, biorhythms and sleep. The research is particularly concerned with oscillation of body weight during the adolescent girls period of one calendar year depending on the influence of different seasons. A partial survey of the research subject is the relationship between BMI and individual chronotype. Specifically, it was examined whether chronotype Lark lower average BMI during the period of one calendar year than the owl chronotype. The research section provides further knowledge on the composition and eating chronotype, and in terms of rationality and regularity of catering. One of the subjects of the thesis is also chronotype influence the dietary habits of individuals, namely their unsuitability.

The thesis is tracking changes in body weight of 15 to 20-year-old male adolescents during one calendar year in the context of a season and typology of a personality in the circadian rhythm area where probands are figuratively categorized into ?larks? whose activity is the highest in the morning hours and ?owls?, in other words people who are more active in the afternoon and evening hours. The theoretical part of the thesis tries to clear key concepts of the research work and the whole thesis alone. The practical part of the thesis explains and describes specific procedures, methods, results, goals and practical recommendations of the project.

This thesis deals with monitoring changes of body weight of adolescent girls at the age of 16 20 years old through one calendar year in the context of a season of the year and chronotypology of a personality. According to this typology the monitored people are divided into so called "larks", who are more active early in the morning and during the day and "owls" whose activity rises in the evening and at night. The theoretical part deals with circadian rhythms, their function, role in the life of an individual and also their disorders. It focuses on a developmental specification of adolescent girls, lifestyle in this period of life, changes of body weight and diet. Another part is the meaning of the sleep, its need and associated with good sleep habits and sleep hygiene. In the practical part there is described a methodology along with the results of the research and employment of this project in practice.

The main objective of the diploma thesis was to create a project of a tutorial on the subject of animal and human biorhythms. The tutorial is intentioned as an additional biology curriculum at grammar schools. Analysis of teaching biorhythms in secondary Biology schoolbooks used in the Czech Republic preceded a composition of this tutorial. Processing literary research based on reading Czech and foreign-language literature was another theoretical resource. The tutorial is divided into three parts {--} {\clqq}Animal Biorhythms``, {\clqq}Human Biorhythms`` and {\clqq}Seasonal Animal Biorhythms``. Some parts of the tutorial were verified in practice.