BACKGROUND: Food texture plays an important role in food intake regulation. In previous studies we showed a clear effect of viscosity on ad libitum food intake and found indications that eating rate, bite size, and oral processing time (OPT) could play a role. OBJECTIVE: The objective was to determine the effect of bite size and OPT of a food on satiation, defined as ad libitum food intake. DESIGN: Twenty-two healthy subjects participated in all 7 test conditions. Bite sizes were free or fixed to small bite sizes ( approximately 5 g) or large bite sizes ( approximately 15 g). OPT was free (only in combination with free bite size) or fixed to 3 or 9 s. Subjects consumed chocolate custard through a tube, which was connected to a peristaltic pump. Sound signals indicated OPT duration. RESULTS: Subjects consumed significantly more when bite sizes were large than when they were small (bite size effect: P < 0.0001) and when OPT was 3 s rather than 9 s (OPT effect: P = 0.008). Under small bite size conditions, mean (+/-SD) ad libitum intakes were 382 +/- 197 g (3-s OPT) and 313 +/- 170 g (9-s OPT). Under large bite size conditions, ad libitum intakes were much higher: 476 +/- 176 g (3-s OPT) and 432 +/- 163 g (9-s OPT). Intakes during the free bite size conditions were 462 +/- 211 g (free OPT), 455 +/- 197 g (3-s OPT), and 443 +/- 202 g (9-s OPT). CONCLUSION: This study shows that greater oral sensory exposure to a product, by eating with small bite sizes rather than with large bite sizes and increasing OPT, significantly decreases food intake.