Bite size, ingestion rate, and meal size in lean and obese women

The effect of bite size on ingestion rate, satiation, and meal size was studied in nine lean and nine obese women. On separate days, subjects were given one of three bite sizes of sandwiches and one of two bite sizes of bagels with cream cheese to eat in a laboratory lunch. Decreasing bite size significantly lowered ingestion rate for the whole meal. The effect was most pronounced at the beginning of meals. As bite size decreased from 15 to 5 g, the average ingestion rate decreased from (mean +/- SEM) 19.4 +/- 2.0 to 15.9 +/- 2.0 g/min (p < 0.001). The initial ingestion rate decreased from 30.0 +/- 2.9 to 19.6 +/- 1.7 g/min (p < 0.001). The larger the bite size, the more quickly ingestion rate decelerated; by the end of meals, ingestion rate was not different across conditions. The decrease in ingestion rate with smaller bites was offset by an increase in meal duration, such that meal size did not differ across conditions. Eating behavior of lean and obese subjects was not different. There were individual differences related to ingestion rate, but these were not related to body weight nor to meal size. These results bring into question the recommendation of behavior therapists that obese people eat more slowly in order to eat less.