Objectives: The main objective of this research was to examine whether dietary habits that deviate from the Mediterranean diet can be considered a risk factor for the development of more severe forms of periodontitis. Materials and methods: This pilot study included 35 participants. The test group included 20 participants who suffered from more severe forms of periodontitis, while the control group included 15 participants with milder forms of periodontitis. Data were collected on age, gender, oral hygiene habits, smoking habits, and the average number of visits to the dentist over a year. Detailed radiological analyses and clinical examinations of the supporting and hard dental tissues were conducted. Data on Oral Health Impact Profile (OHIP-14), body mass index (BMI), and waist-to-hip ratio (WHR) were collected. Furthermore, participants completed questionnaires about their diet (MEDAS and MDSS) to check adherence to the Mediterranean diet. Results: The results of this study showed deviations of our participants from the pattern of the Mediterranean diet and no association was found between more severe forms of periodontitis and non-adherence to the Mediterranean diet. More detailed analysis revealed differences between groups in the consumption of legumes, nuts, and sweets. BMI values were significantly higher in the group with more severe forms of periodontitis. On the other side, logistic regression analysis showed that only age was a significant predictor of more severe forms of periodontitis (P=0.029). Both groups had acceptable oral hygiene habits, likely as a result of receiving active periodontal therapy. Conclusion: Deviation from the principles of the Mediterranean diet was not shown to be a risk factor for the development of more severe forms of periodontitis. An increased body mass index has not been shown to be a risk factor for more severe forms of periodontitis.