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The effect of viscosity on ad libitum food intake
The aim of this 2008 experiment was to evaluate the impact of altering food viscosity on food intake (when given unrestricted access) in a real-life setting, and to assess whether a difference in consumption is related to either eating rate or effort. While 108 participants were placed in a real-life setting and given a chocolate flavored liquid, semi-liquid and semi-solid milk-based product (all similar in palatability, macronutrient composition and energy density), 49 subjects consumed the liquid or semi-solid product in the laboratory. The outcome measures were eating rate and effort, which could be determined by feeding the product through a peristaltic pump. The liquid form was reported to have been consumed the most in the real-life scenario at 809+/-396 g, which was 14% more than the semi-liquid, and 30% more compared to semi-solids. Disregarding eating effort in the laboratory setting resulted in a 29% higher intake of the liquid product relative to that of the semi-solid form. Standardizing the eating rate reduced this difference in consumption of the liquid and semi-solid test samples to 12%. If controls were not considered, the variation in quantity eaten between liquids and semi-solids was comparable to the real-life setting. In summary, the level of food consumption is greatly affected by viscosity, even if similar in palatability, macronutrient composition and energy density. The higher eating rates of liquids may play a factor in the difference in consumption observed. [NPID: perception, altered food viscosity, viscosity, food viscosity, liquid calories, chewing, oral processing, highly palatable foods, macronutrient composition, energy density]
Year: 2008
