Effects of Food Form and Fitness on Appetite and Digestion.

Energy-yielding fluids induce weaker appetitive and compensatory dietary responses than
energy-matched semi-solids or solids. This is problematic because the high and increasing
contribution of energy from beverages in the diet may enhance positive energy balance and
weight gain. The prevailing view of the overweight/obesity problem is that it stems from a
small, sustained positive energy balance. It follows then that only small changes, perhaps
manipulations in the rheological characteristics of the diet, will be required to correct the
problem. Certain populations that are more prone to weight gain may benefit from such
manipulations. Obese individuals have a higher beverage intake and experience greater weight
loss with reductions in beverage intake. Further, there is evidence that obese individuals
consume more energy after a liquid pre-load than their lean counterparts, yet there is no
difference in energy intake after a solid load. In contrast, habitual exercisers have been
shown to have an increased accuracy of short-term regulation of food intake at meals
following liquid preloads. A better understanding of the mechanisms by which beverages and
energy-matched solid food forms elicit differential appetitive and dietary responses in these
populations needed. This research will attempt to identify the influence of physical fitness
and body fat on the ability to compensate for the energy content of solid and liquid preloads
by reduction in energy intake at a subsequent ad libitum meal (i.e., acute compensation) and
over the course of the day (i.e., short-term compensation). Furthermore, this study will
examine the cognitive contribution to differential responses to energy-matched beverage and
solid food forms and the effects of mastication on appetite, GI transit, glycemic response,
and selected endocrine responses.