But new research suggests that keeping food in the mouth for longer periods (through smaller bites, more chewing, slower eating rate and longer meal duration) may reduce overall meal size and improve satiety responses.
For the analysis, P.S. Hogenkamp and H.B. Schiöth at the University of Uppsula in Uppsula, Sweden, pooled the results of 33 experiments that investigated the impact of changes in bite size, number of chews, and texture (viscosity and hardness), as well as changes in eating rate (grams or kcals consumed per minute) on food intake to determine the effects on satiation and perceived fullness, or satiety.
To account for variances across foods and individuals, the selected experiments incorporated foods eaten on varying levels of oral processing time and intensity (low versus high), due to large versus small bite size, high versus low total number of chews, and liquid versus semi-solid textures. The experiments also incorporated eating rates (quick versus slow) and overall meal duration (short versus long).
Effects observed on satiation and satiety
Based on the results of 17 experiments on adult subjects, 12 saw a decrease in ad libitum intake, or satiation, when foods were eaten with small bite sizes or a higher number of chews, or when eating semi-solid foods compared with iso-caloric liquid foods. A lower eating rate also resulted in lower meal size compared with higher eating rate.
Perceived satiety, on the other hand proved slightly murkier. Results from an additional 16 experiments (also on adults) showed that increasing the number of chews or consuming foods with higher viscosity increased perceived fullness in some, while differences in eating rates didn’t consistently affect perceived satiety. Responses of hormones associated with satiety were also inconsistent, yet overall, the authors concluded that increased oral processing time also increased satiety-related hormone responses.
Overall, the authors concluded that “all aspects of oral processing and eating rate can be an effective strategy to impact satiation and perceived fullness,” which, in turn, could have major implications for the food manufacturing industry as well as efforts to combat obesity.
Potential for lasting benefits
“It has been observed that bite sizes change with hardness of the food, with larger typical bite sizes for softer foods, and that bite sizes may increase with portion size,” the authors wrote. “The food industry may consider determinants of oral processing time in their product development and packaging design to contribute to the control of food intake.”
Furthermore, he authors found that slowing down the normal eating rate could help control energy balance and meal size, making it a potentially “useful therapy to include in programs aimed on reducing obesity.” As individuals become familiar with their own oral processing behaviors, they may be able to use this knowledge as a strategy to improve control over their food intake.
“Future research should be aimed on further understanding of the factors that may interact with bite size, chewing, eating rate and texture to promote a reduced food intake on the long term,” the authors concluded.
Source: Trends in Food Science & Technology
“Effect of oral processing behavior on food intake and satiety,”
Trends in Food Science & Technology (2013), doi: 10.1016/j.tifs.2013.08.010.
Authors: Hogenkamp, P.S., Schiöth, H.B.