Investigation of the Effects of Bariatric Surgery on Taste Reward in Humans

Investigation of the Effects of Bariatric Surgery on Taste Reward in Humans

The investigators hypothesize that some of these changes in the reduced appetite after surgery may be due to alterations in taste. The aim is to compare obese patients before and after bariatric surgery (gastric bypass and banding) to define the reward value of sweet, fatty and vegetable/fruit taste in obese individuals, and how this changes after surgery.

Severe obesity is associated with excessive food eating and appetite. Bariatric surgery (also known as 'obesity surgery' or 'weight loss surgery') is a well known treatment for severely obese individuals. The way in which these operations achieve weight loss is not fully understood. The investigators hypothesize that some of these changes in the reduced appetite after surgery may be due to alterations in taste. The aim is to compare obese patients before and after bariatric surgery (gastric bypass and banding) to define the reward value of sweet, fatty and vegetable/fruit taste in obese individuals, and how this changes after surgery.

Inclusion Criteria:

• BMI of 18-25 for normal weight volunteers
• BMI of >30 for obese patients

Exclusion Criteria:

• Pregnancy
• breast feeding
• substance abuse
• consumption of more than 3 alcoholic units per day
• severe psychiatric illness
• lack of understanding of test instructions
• diabetes mellitus
• chronic medical conditions making a general anaesthetic unsafe
• allergy to stimulus ingredients
• active smoking