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.

Inclusion Criteria:

• 18-50 years of age BMI of 18-23 kg/m2 (lean) or 30-35 kg/m2 (obese) Sedentary physical activity level (<70th¬ percentile of estimated VO2max for age and sex) or physically Active/Exercisers (>70th¬ percentile of estimated VO2max for age and sex) Good health and not taking any medications known to influence appetite Non-smokers Not pregnant or lactating Weight stable (≤ 3 kg within last 3 months) Dietary restraint score <11 on the Three Factor Eating Questionnaire (included in the on-line screening questionnaire) Glucose Tolerant or Non-Diabetic (fasting blood glucose of <100 mg/dL) Self-reported consumer of breakfast and lunch

Exclusion Criteria:

• History or presence of significant metabolic diseases that may impact study results (i.e., endocrine, hepatic, renal disease) Individuals planning on starting a new diet or exercise regimen during the course of the study Use of obesity pharmacotherapeutic agents or over-the counter anti-obesity agents within the last 3 months Underlying conditions such as any cardiovascular, pulmonary, or neurological dysfunction that may be aggravated with exercise