Obesity affects a third of adults in the United States. The most effective treatment for weight loss is bariatric surgery, and the most common surgery performed in the US is Roux-en-Y Gastric Bypass (RYGB). However, a significant number of patients regain weight that was lost after surgery. The mechanisms for weight regain are likely multifactorial, but not well understood. Disordered eating behaviors and dilated gastrojejunostomies (GJ), which presumably allows a patient to consume larger portion sizes during a meal, correlate with weight regain. Moreover, some data suggest that changes to the gut anatomy may drive eating behaviors and food preferences. However, no studies have simultaneously evaluated functional gastric volume (the volume of solid or liquid food that can be consumed to a level of comfortable fullness in one sitting), anatomical gastric pouch size and GJ diameter, and eating behaviors in patients who maintained their post RYGB weight compared with patients who have regained weight from their maximum weight loss after RYGB to determine the relationship among post RYGB eating behavior, functional and anatomical gastric pouch size, GJ diameter and weight change. Accordingly, the objectives of this proposal are to compare 1) eating behaviors 2) functional gastric volume and 3) anatomical dimensions of the gastric pouch and GJ in patients who are \>2 years post RYGB and have regained \>20% of their maximum lost weight and those who are \>2 years post RYGB and have maintained at least 90% weight loss since surgery. The following specific aims will be evaluated:

Aim 1. Evaluate whether differences in eating behaviors exist between subjects who have maintained weight loss after RYGB or regained \>20% of their maximum lost weight. The investigators hypothesize that subjects who have regained weight after RYGB will have higher scores on binge eating behaviors and an increased craving for sweets compared with patients who have maintained weight loss after RYGB. Eating behaviors will be determined by performing the Yale Food Addiction Scale (YFAS), Eating Disorder Examination (EDE), The Food Craving Inventory (FCI), and the National Cancer Institute (NCI) ASA24.

Aim 2. Evaluate whether differences exist in functional gastric volume between subjects who have maintained weight loss after RYGB or regained \>20% of their maximum lost weight. The investigators hypothesize that patients who have regained weight after RYGB will have an increased functional gastric volume to both solids and liquids compared to subjects who have maintained weight loss after RYGB. Functional gastric volume will be measured during both a solid and liquid meal test.

Aim 3. Evaluate whether differences exist in gastric pouch and GJ sizes between subjects who have maintained weight loss after RYGB or regained \>20% of their maximum lost weight. The investigators hypothesize that patients who have regained weight after RYGB will have increased gastric pouch size and GJ diameter compared with patients who have maintained their weight loss after RYGB. Anatomical dimensions of the gastric pouch and GJ will be determined by using an articulated measuring tool during upper GI tract endoscopy.