Overweight and diseases connected with it are increasing problems in children and adults. We often observe change of weight in thyroid disease. It is emphasized that changes in hormones such as peptide levels are in close relationship with regulation of body mass: ghrelin increases appetite and in effect increases body mass, but obestatin decreases appetite and weight. The aim of the study was to analyze the relationship between lipid-carbohydrate metabolism parameters and thyroid hormones and the level of gastric peptides (ghrelin and obestatin) in young patients with Graves' disease, Hashimoto's thyroiditis and in children with simple goiter. The study group formed 78 patients suffering from Graves' disease (29 girls and 2 boys; aged from 6 to 21 - mean 15,2 yrs) and Hashimoto's thyroiditis (29 girls and 3 boys; aged from 9 to 18--mean 14.5 yrs). The control group consisted of children with simple goiter--13 girls and 2 boys; aged from 9 to 18 --mean 14.8 yrs. In all patients, ghrelin and obestatin levels were analyzed by the RIA method (Phoenix Pharmaceuticals, USA). In children and adolescents with untreated Graves' disease we found higher levels of insulin and HOMA-IR index compared to the group of children with simple goiter (34 +/- 8 microIU/mL vs 15 +/- 5; p < 0.03; 7.3 +/- 1.2 vs 3 +/- 0.3, p < 0.03). No significant correlations were observed of gastric hormones with antithyroid antibodies, lipids or h-CRP in patients with untreated hyperthyroidism and subclinical hypothyroidism. Positive correlation was noted of insulin and glucose levels and HOMA-IR index with ghrelin level in children with newly diagnosed Graves' disease (r = 0.109, p < 0.045; r = 0.176, p < 0.036; r = 0.174, p < 0.037). The correlation was also positive between obestatin level and HOMA-IR index in children with subclinical hypothyroidism in the course of Hashimoto's thyroiditis (r = 0.497, p < 0.011). We also examined the relationship between BMI, thyroid hormones and the level of gastric peptides. In untreated GD patients, ghrelin level exhibited a significant negative correlation with fT3 and fT4 (r = -0.38, p < 0.041; r = -0.459, p < 0.012) and positive with TSH (r = 0.38, p < 0.041) and BMI (r = 0.8, p < 0.01). In conclusion, we suggest that the disturbances in carbohydrate parameters in thyroid diseases have an essential effect on change of hormone-controlled appetite: ghrelin (in hyperthyroidism) and obestatin (in Subclinical hypothyroidism).