The aim was to compare the relative intensity (RI) and activity of BChE bands (G1, G1-ALB, G2 and G4) in obese and control individuals, and search for an association between the activity of each band with obesity and SNPs of exons 1 and 4 of the BCHE gene. The gene discussed is BCHE; the disease is obesity due to melanocortin 4 receptor deficiency.