Gut hormones [ghrelin, peptide YY (PYY) and glucagon-like peptide-1 (GLP-1)] are an important group of hormones that target appetite control. They are released from endocrine L cells of the small bowel in proportion to the volume, components and calories in a meal. In the current study, 20 g of gelatin (flavored and sweetened) were given to obese patients (n=12) and lean subjects (n=10). Subsequently, plasma samples were collected at-30- minute intervals up to 180 minutes and glucose, insulin, PYY, GLP-1 and ghrelin were assayed using specific and sensitive immunofluorometric and radioimmunoassays. As expected, obese patients had normal serum glucose levels, higher serum insulin, and lower plasma concentration of ghrelin at all times compared to lean subjects. GLP-1 plasma levels were significantly elevated at 60 minutes, peaking at 120 minutes in obese patients and lean subjects. As a consequence, there was a significant rise in serum insulin levels with a significantly higher peak level at 60 min (obese) and 30 min (lean). There were no significant changes in PYY plasma concentrations and no correlation was found between body mass index and concentrations of ghrelin, PYY and GLP-1 in the group of obese patients. In conclusion, a single gelatin meal induces a rise in plasma GLP-1 followed by an increase in serum levels of insulin. These findings may be applied to maximize satiety in obese patients as a means of improving adherence to calorie-controlled diets as well as provide better control of diabetic patients.