brain, appetite, teens, and exercise

Conditions: Energy Balance; Appetitive Behavior; Obesity

Summary: the long-term goal is to develop effective, evidence-based lifestyle interventions to prevent and treat childhood obesity and related co-morbidities. the short-term goal, and the purpose of this application, is to quantify appetite and neural mechanisms of food reward in overweight/obese (ow/ob) sedentary youth and to quantify changes following the implementation of a physical activity intervention. the central hypothesis is that appetite becomes dysregulated at low levels of physical activity via neural reward pathways, and appetite control will improve following a long-term exercise intervention. the investigators consider this project a pilot study designed to generate data to be used for future external funding opportunities, demonstrate collaboration between researchers, and test the feasibility of the protocols.

specific aim 1: to identify associations between neural, psychological, and hormonal appetite control pathways using subjective and objective measures of appetite and neurocognitive assessments of reward pre-intervention. hypothesis 1: there will be significant cross-modulation of appetite across neural (brain activation), psychological (subjective hunger), and hormonal pathways (satiety biomarkers), though the temporal relationship between each in response to feeding is unknown. specific aim 2: to assess the effectiveness of a physical activity intervention on eating behavior in adolescents; ow/ob inactive adolescents will be randomly assigned to a 3-month exercise intervention (exercise +newsletter), or a control condition (newsletter). hypothesis 2a: those exposed to the exercise intervention will have greater improvements (compared to control group) in appetite (subjective self-reported hunger and palatability responses, and, objectively, satiety and appetite hormones glucose, insulin, ghrelin, and leptin, and calories consumed during ad libitum meal). hypothesis 2b. compared to pre-intervention, ob/ow youth in the exercise group will show decreased reward activation in regions of the brain when making decisions about appetizing foods compared to post-intervention when hungry and when fed. in self-control regions, compared to pre-intervention, the investigators will observe increased activity in both hungry and fed conditions. at the end of the proposed study, it is the expectation that the investigators will have collected important preliminary data regarding how long-term structured exercise acts upon appetite and neural mechanisms related to food reward in adolescents. findings are key not only to interventions targeting ow/ob youth, but also to public policy and health recommendations for the importance of physical activity in children.

Eligibility criteria:
inclusion criteria * overweight/obese (bmi ≥85th to \<99th percentile for age and sex) * weight stable * ages 14-17 * no meds that may alter metabolism * sedentary (\<20 min/day exercise) * at risk for t2d, according to american diabetes association (ada) criteria: * family history of t2d in first- or second- degree relative * race/ethnicity (native american, african american, latino, asian american, pacific islander) * signs of insulin resistance * maternal history of diabetes for gestational diabetes during child's gestation * willing to participate in an exercise program * willing to provide permission/assent exclusion criteria: * bmi \<85th percentile for age and sex * weight not stable * age \ 17 * on meds that may alter metabolism * active (\>20 min/day exercise) * not at risk for t2d, according to american diabetes association (ada) criteria (see above) * not willing to participate in an exercise program * not willing to provide permission/assent