Introduction and objective: There is currently a significant increase in the prevalence of obesity among children worldwide. The aim of the study was to analyse the diet and eating habits of adolescents depending on the presence of obesity and demonstrate the impact of incorrect eating habits on lipid and mineral metabolism disorders. Materials and methods: The study involved 133 adolescents aged 12–17 years: 101 adolescents with obesity and 32 healthy children in the control group. The study plan provided for a combination of standard clinical and anamnestic evaluations, including a study of eating habits, and laboratory-instrumental research. Results: In adolescents with obesity, violations of the regularity of eating (p < 0.001), as well as the habit of snacking on bakery products and sweets during the day (p < 0.01) and late dinner (p < 0.001) were significantly more common compared to the control group. Adolescents with obesity consumed sweets, bakery products, fast food products, chips, crackers significantly more often, and vegetables less frequently, compared to their peers in the control group, every day or several times a week (p < 0.05). Adolescents with obesity had significantly lower levels of zinc and magnesium compared to the control group (p < 0.05). Conclusions: The study revealed the problem of irrational and unbalanced nutrition in adolescents with obesity. The obtained data may become the basis for timely correction of the diet of obese adolescents, which will prevent the development of disorders of the gastrointestinal tract, and halt the progression of the underlying disease.