Objectives: To investigate nutritional habits and attitudes in male and female fitness center users, as well as the degree of adherence to the Mediterranean diet (MD) and its components. Materials and Methods: This was a cross-sectional study, including 405 fitness center users in Split, Croatia, conducted from July to October 2021. All of the participants were active fitness center users between the ages of 18 and 65 and trained at least once a week, professional athletes were excluded from the study. Online Google Forms® survey was distributed via e-mails and social groups and it consisted of two main parts, with general information and dietary supplements information collection in first, and adherence to MD and its components using Mediterranean Dietary Serving Score (MDSS) in second. Results: The study included 193 male and 212 female fitness center users. The males consume more dietary supplements when compared to females (63.7 vs. 49 %, P=0.004), including whey protein (77.7 vs. 47.6 %, P<0.001) and creatine (25.3 vs. 3.8 %, P<0.001). Furthermore, MDSS analysis have shown that investigated population most commonly followed eating guidelines for potatoes (90.1%) and white meat (91.4%), with significantly more females where compliant to the recommendations for dietary intake of sweets (58.5 vs. 41.5 %, P<0.001). Further MDSS analysis have shown that median MDSS score was significantly lower in men when compared to women (7.0 (5.0-8.25) vs. 7.0 (6.0-10.0), P=0.030). Moreover, 19 males (9.8%) and 32 females (15.1%) where overall adherent to MD, without statistical significant difference between the genders (P=0.149). Finally, a multiple logistic regression model that was used to determine independent variables associated with positive adherence to MD showed that none of the investigated parameters proved to be of statistical significance. Conclusion: Majority of fitness center users are using some dietary supplementation, most commonly whey protein. Overall adherence to Mediterranean diet was low. Females have a higher total MDSS score and no significant difference in adherence was observed between the genders.