To evaluate the influence of Helicobacter pylori infection on the gastric regulation of food intake and body weight. H. pylori infection leads to a decrease of circulating ghrelin through a reduction of ghrelin-producing cells in the gastric mucosa and increases the amount of gastric leptin with no effect on circulating leptin levels. Eradication of H. pylori reverses the abnormal regulation of gastric hormone secretion. This finding is suggested to favor weight gain after H. pylori eradication and points to the potential effect of H. pylori in the pathophysiology of obesity. H. pylori has an influence on the release of gastric hormones and therefore plays a role in the regulation of body weight, hunger and satiety.