Objectives: The overall objective of Project 1 is to examine the metabolic and behavioral links betweendietary intake and its subsequent effects on circulating appetite regulating hormones and physical activitylevels in Hispanic and African American adolescents. Our major unifying hypothesis is that diets comprisedof high sugar, energy dense, low fiber meals, are associated with a post-prandial metabolic, hormonal andpsychosocial profile that promotes overeating and sedentary behavior.
Specific Aims : (1) Compare theeffects of a HIGH SUGAR, LOW FIBER (HSLF) meal versus a LOW SUGAR, HIGH FIBER (LSHF) meal oninsulin dynamics, selected gut peptides, mood and levels of physical activity in minority adolescents, (2)Explore the effects of HSLF versus LSHF meals on post-prandial ad libitum food intake, (3) Exploredifferences in reaction to HSLF versus LSHF meals in lean and overweight adolescents and (4) Examineethnic differences in meal responses between Hispanic and African American children. Research Designand Methods: We will employ a cross-over design with a 3-4 week washout period where normal weightand overweight African American and Hispanic youth come to our Observation Lab in a fasting state andconsume high sugar and low sugar meals at separate visits in random order. Meal consumption will befollowed by five hours of intensive observation in which we quantify real-time physical activity in laboratorysetting that was designed to offer equally attractive choices for active or sedentary behaviors. After 5 hours,participants will be offered food platters with an array of food types and be invited to eat ad libitum.Subsequent energy and nutrient intake will be quantified. Rationale: This study is prompted by threeobservations: (1) The disproportionate levels of obesity and risk for type 2 diabetes and cardiovasculardisease in Hispanic and African American children; (2) The rapid decline in physical activity during pubertyespecially in Hispanic and African American adolescents, and (3) Children, and particularly minority children,tend to have diets high in added sugars and low in fiber. Thus, it is imperative to improve our understandingof the interrelationships between dietary intake, physical activity and risk factors for type 2 diabetes andcardiovascular disease in minority youth, particularly during puberty, when physical activity levelssignificantly decline. Relevance to public health: This study will provide new information on the acuteeffects of meal composition on mood and subsequent choices of physical activity in normal weight, healthyoverweight and insulin resistant overweight Hispanic and African American youth. Furthermore, we suggestthat our findings may potentially lead to a better understanding the acute affects of poor nutritional choiceson physical activity in minority adolescent populations at high risk for obesity, diabetes type 2, and otherobesity-related diseases.
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