The purpose of this study is to look at certain areas of the brain that are related to addictive behaviors, such as overeating. These areas are called 'dopamine type 2 receptors' (DRD2/3) and other studies have shown that obese people have less of these. We propose that low DRD2/3 availability seen in morbidly obese subjects will change with weight loss associated with bariatric surgery.

The purpose of this study is to look at certain areas of the brain that are related to addictive behaviors, such as overeating. These areas are called 'dopamine type 2 receptors' (DRD2/3) and other studies have shown that obese people have less of these. We propose that low DRD2/3 availability seen in morbidly obese subjects will change with weight loss associated with bariatric surgery.

Inclusion Criteria:

• Ages 18-60 years
• BMI equal to or greater than 40, or equal to or greater than 35 if there are 2 or more co-morbidities
• Weight less than 350 pounds

Exclusion Criteria:

• History of substance abuse,including but not limited to alcohol, cocaine, marijuana, heroin, nicotine
• History of psychiatric disorders
• Use of any antidepressants or psychotropics in the past 12 months
• Diabetes Mellitis
• Positive pregnancy test
• Any condition felt by the PI or co-investigators to interfere with the individual's ability to complete the study
• Subjects on medications for the last 3 months, such as sibutramine, which could affect the quality of the study, as determined by the PI
• Inability to travel to Nashville, TN four times