The difference between weeks 0 and 12 in the obesity group (p < 0.001) shows the effect of cafeteria diet on ALT activity; the difference between obesity group and obesity + caffeine group at week 12 (p < 0.001), the difference between control and caffeine group (p < 0.05), obesity + caffeine group (p < 0.05) and the statistical difference between weeks 9 and 12 in caffeine group (p < 0.05) shows the effect of caffeine on ALT activity. This evidence concerns the gene GPT and obesity due to melanocortin 4 receptor deficiency.