THEORETICAL BASIS: A sedentary lifestyle, consumption of inappropriate food, smoking or alcohol consumption can contribute to the overall deterioration of lifestyle and lead to weight gain. Lifestyle includes nutrition, physical activity, sleep, psychological well-being, good relationships or job satisfaction. We can influence some parts of our lifestyle, but we cannot influence many other factors like genetic predisposition or the environment in which we live. OBJECTIVE OF STUDY: The objective of the study is to evaluate the relationship between lifestyle and BMI (Body Mass Index), as well as differences based on age and sex. METHODOLOGY: A self-constructed questionnaire containing 71 questions was used to determine information about lifestyle. The collected data was based on the assessment of body mass index (BMI) and age, all respondents were measured using the stadiometer and InBody 270. The group included 323 adults (156 men and 167 women) and was divided according to BMI (BMI lower than 25 kg/m2, and BMI of 25 kg/m2 or higher). The selected lifestyle characteristics were grouped to create a positive score including positive lifestyle factors, a negative score including negative lifestyle factors, and an overall healthy lifestyle score that included positive and negative scores. RESULTS: We found out that physiological BMI (18.5-24.9 kg/m2) was more common in respondents with higher education and students. The most respondents prefer omnivorous diet, in lower BMI group were mainly non-smokers and occasional consumers of alcohol, in comparison to higher BMI group where were former smokers and those who abstained from alcohol. All scales of lifestyle are sex-related and negative healthy lifestyle score also depend on BMI. Effect of age is not significant. CONCLUSIONS: According to our study, people with a physiological BMI have a significantly healthier lifestyle compared to overweight or obese people. The overall lifestyle values, as well as the positive and negative lifestyle scores, depend on sex; the negative healthy lifestyle score also depends on BMI.