Objectives Alexithymia and low health literacy are the barriers of self-management. This study aims to examine the relationship between alexithymia, health literacy and diet quality in obese adolescents, and their effects on anthropometric and biochemical markers. Methods The 20-item Toronto alexithymia scale (TAS-20) was used to determine the alexithymic traits of the adolescents, and “The Newest Vital Sign” (NVS) scales were used to determine their health literacy levels. Diet quality was evaluated with the Healthy Eating Index-2010 (HEI-2010). Results 39.7% of the obese adolescents were alexithymic, and 69.4% of alexithymics and 35.1% of non-alexithymics had metabolic syndrome. Alexithymic adolescents were lack of adequate health literacy. There were positive correlations between alexithymia scores and insulin, triglyceride, systolic and diastolic blood pressure levels, and all anthropometric values except height (p<0.05). There was a negative correlation between alexithymia scores and health literacy scores (p<0.05). There were negative correlations between health literacy and alexithymia scores, insulin, total cholesterol, triglyceride, ALT, systolic, diastolic blood pressure levels and all anthropometric values except height, and positive correlation was observed between health literacy scores and diet quality (p<0.05). Total HEI score was negatively correlated with waist circumference, neck circumference, body weight, BMI, triglyceride, AST, ALT, systolic and diastolic blood pressure, and positively correlated with health literacy and HDL levels (p<0.05). Conclusions As alexithymia severity increased in obese adolescents, the degree of obesity and the incidence of metabolic syndrome increased while the level of health literacy decreased. The increase in health literacy levels, on the other hand, decreased the level of alexithymia and increased the quality of the diet.