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

Completed

Brief Summary: 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.

Detailed Description: 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.

Recruitment & Eligibility

Inclusion Criteria

Exclusion Criteria

Primary Outcome Measures

Name	Time	Method
Breakpoints as Assessed by Change in the Number of Mouse Clicks in the Last Completed Ratio	2 weeks pre and 8-12 weeks post operatively for surgical patients or on two occasions 10-14 weeks apart for normal weight control group	Patients were placed in front of a computer screen and a plate of 20 chocolate candies. The following prompt appeared on the screen: "You can earn food by clicking on the mouse button. Click as much or as little as you like. When you no longer want to continue, press the spacebar to stop the session."Upon completion of each ratio a message box appeared on the screen: "You have earned food. Enjoy your reward and after you have swallowed it completely you may click on OK to continue with the programme."After ingesting the reward, the patients pressed the OK button in the message box only if they wished to progress to the next ratio to obtain another chocolate candy. The starting ratio was 10 clicks with a geometric increment of 2 (i.e., 10, 20, 40, 80, and so on). When the effort of pressing the mouse button was greater than the rewarding value of the chocolate candy, patients pressed on the space bar to terminate the session. This indicated that the breakpoint was reached.

Secondary Outcome Measures

Name	Time	Method
Hunger	2 weeks pre and 8-12 weeks post operatively for surgical patients or on two occasions 10-14 weeks apart for normal weight control group	Visual Analogue Scale ratings of hunger. The scale is 100mm line with two anchors at each end. Scores are recorded by making a handwritten mark that represents a continuum between "not hungry at all" and "Extremely hungry." The score of 0 represents least hunger. The score of 100 represents extreme hunger. change in hunger levels quantified by a 100mm visual analogue scale
Body Mass Index	2 weeks pre and 8-12 weeks post operatively for surgical patients or on two occasions 10-14 weeks apart for normal weight control group	change in BMI will be quantified based on the participants weight in kilograms and height in meters