Central Nervous Processing of Visual Food Stimuli in Severely Obese Subjects

Central Nervous Processing of Visual Food Stimuli in Severely Obese Subjects and After Roux-en Y Gastric Bypass Surgery - a FMRI Study

Recent evidence has pointed to distinct alterations of brain functions in obese subjects some of which may even be causative for their obesity. The objective of this study was to examine food and non food related alterations in brain functions after excessive weight loss due to Roux-en Y gastric bypass surgery (RYGB), one of the most successful therapeutic approaches for long lasting weight loss. The investigators hypothesized that obese as compared with lean women show an altered activation pattern in the brain areas involved in the homeostatic regulation of eating behavior, i.e. the hypothalamus, in reward-related brain areas, such as the orbital frontal cortex (OFC) and the striatum as well as in prefrontal inhibitory control areas. Furthermore, the investigators hypothesized that women who had undergone a RYGB operation show a brain activity pattern that more closely mimics that of lean than severely obese women. In a supplementary test the investigators will assess gastrointestinal and metabolic response to a standardized meal in order to elucidate putative correlation of these responses with the results of fMRI scannings.

Inclusion Criteria:

• women with BMI > 35kg/m2
• women, who had undergone gastric bypass surgery at least one year ago
• lean women

Exclusion Criteria:

• known psychiatric or neurological diseases
• current medication with drug acting on the central nervous system
• drugs that are known to affect eating behavior
• contraindication for the fMRI scanning, e.g. metal implants or metal containing tattoos