Abnormal gastric emptying in the obese has been previously suggested. To explore this concept, we studied a group of 77 subjects composed of 46 obese and 31 age-, sex-, and race-matched nonobese individuals. All of the subjects underwent quantitative fluid/solid gastric emptying assays utilizing a dual radionuclide technique. For the solid phase, obese subjects were found to have a more rapid emptying rate than nonobese subjects (p less than 0.05). Obese men were found to empty much more rapidly than their nonobese counterparts (p less than 0.01). In 4 obese subjects whose weight loss was to within 10% of their ideal weight, repeat gastric emptying studies revealed no change in liquid or solid emptying rates. The elimination patterns of gastric emptying for liquids and solids were identical to those described previously, and did not differ between the obese and nonobese groups. No correlation between body surface area and gastric emptying rates of solids or liquids could be found. The rate of solid gastric emptying in the obese subjects is abnormally rapid. No clear-cut explanation for this finding yet exists.