effects of food form on cephalic phase responses

Conditions: Obese; Overweight

Summary: this study has two main aims: 1) to determine if ingestion of solid or beverage food forms will change appetite hormone responses, and 2) to determine whether "learning" (defined as 2 week daily consumption) about the metabolic consequence of ingesting solid or beverage foods forms varying in energy alters appetite hormone responses. beverage consumption has been implicated in the problem of obesity. however, the exact relationship between beverages, lower appetitive response and lower compensatory dietary responses remains unclear. this study aims to address this gap in the research. for aim 1, the null hypothesis is that the energy in beverage and solid forms will not affect appetite hormonal responses differently. the alternative hypothesis is that exposure to the energy-yielding beverage will elicit a lower appetitive hormone response compared to oral exposure to the solid food form. for aim 2, the null hypothesis is that learning will not change appetite hormone responses. the alternative hypothesis is that learning will decrease appetite hormone responses in the non-energy-yielding beverage more than in the energy-yielding beverage.

the main aims will be studied in 3 phases. in phase 1,the unconditioned cephalic phase responses of participants to nutritive and non-nutritive beverage and solid food forms will be determined. in phase 2, participants will consume a randomly allocated solid food or beverage (either nutritive or non-nutritive) consecutively for 2 weeks. in phase 3, (which will occur immediately after the end of phase 2), participants will be retested for their cephalic phase responses to determine if there is an effect of learning on appetite hormone response.

Eligibility criteria:
inclusion criteria: * body fat percentage \> 25% for men and \> 32% for women. bmi of 24 kg/m2- 37kg/m2 * no purposeful use of foods or beverages that are sweetened with non-nutritive sweetener \> 3 times a week * no purposeful addition of non-nutritive sweetener to foods and beverages \>3 times a week * no phenylketonuria (pku) * rate palatability of test load and food sample as greater than 5 on a 9 point category scale. * be willing to eat at least 100 grams of carbohydrates for three days prior to each test day * self-reported consumer of breakfast and lunch * be willing to eat macaroni and cheese during breakfast-lunch hours * not taking medications known to influence appetite * non-smoker \>1 year or more * habitual activity pattern over the last 3 months and no plan to change this over the course of the study * not on any extreme diet (e.g. atkins diet) * weight stable (≤ 5 kg change over the last 3 months) * not a restrained eater (have a dietary restraint score of \<9 on the three factor eating questionnaire-restraint section) * not a disordered eater (have a score of \<20 in the eating attitudes test-26) * have not donated blood for at least 3 months prior to participating in the study * indicate no plan to donate blood during, and for three months after the study

Keywords: peptides hormones appetite humans obese beverage solid food cephalic phase