African American (AA) women have the highest rates of obesity in the U.S. Despite this, AA women are underrepresented in weight loss trials, and when they are represented, they lose less weight than Caucasian participants. Eating behavior is influenced by a convergence of processes in the brain, including homeostatic factors and motivational and reward processing. Initial functional magnetic resonance imaging (fMRI) studies from our group have identified brain regions, implicated in motivation and reward processing that respond differently to visual food cues in obese and healthy weight individuals, and are positively correlated with reports of hunger in obese participants. In addition, hormones and metabolic factors are important contributors to weight gain and loss. Though shedding some light on neural and hormonal contributions to overeating, we do not know whether results from our previous work in mixed racial groups (predominantly Caucasian) generalize to under-represented minority populations. Given the high treatment failure rates among obese AA women, efforts are needed to further characterize treatment responders and non-responders in this population. We will scan obese and healthy weight female AA participants with a food motivation fMRI paradigm during a baseline state and after obese participants have completed a diet-based weight loss intervention. Obese participants will then be followed though a 6-month weight maintenance period. We will also acquire measures of metabolism and hormones (adiponectin, ghrelin, and leptin). The study will address three Specific Aims: 1. Examine brain activation, metabolic and hormonal baseline differences between obese and healthy weight AA women. 2. Identify brain activation, metabolic, and hormonal changes in initially obese AA women following successful weight loss or unsuccessful weight loss. 3. Identify brain activation, metabolic, and hormonal predictors of weight loss and weight loss maintenance in obese AA women. Findings from this study will have significant implications for understanding mechanisms of obesity, weight loss, and weight loss maintenance in AA women and may ultimately lead to more effective interventions.
Results from this work are highly significant to public health and could lead to a better understanding of how differences in brain activation, metabolism, and hormones relate to obesity in AA women. Dietary interventions, while generally effective, do not work for everyone, and weight regain is a significant problem. Treatment failure is especially a problem in AA women. Findings from this study may ultimately lead to more effective and targeted interventions for inducing weight loss in AA women.
