Gastric bypass surgery (GB) is a safe, effective treatment for morbid obesity(Reference Colquitt and Pickett1). Aside from reduced energy consumption, patients report changes in food preferences and appetite that may contribute to weight loss post-surgery(Reference Mathes and Spector2, Reference Miras and Le Roux3). Food preferences can be separated into two constructs; ‘liking’ (pleasure) and ‘wanting’ (motivation/desire to eat)(Reference Berridge and Robinson4) which may be influenced by physiological and psychological changes post-surgery. The aim of this study was to investigate changes in food preferences (‘liking’ and ‘wanting’) in GB patients from pre- to post-surgery, compared to weight-stable controls.
Nineteen patients (45·2 ± 12·5 years, Body Mass Index (BMI): 45·3 ± 6·4 kg/m2) and sixteen time-matched controls (44·7 ± 15·6 years, BMI: 25 ± 4·4 kg/m2) completed the computer-based Leeds Food Preference Questionnaire, which assesses preferences for sweet/savoury foods and low-fat/high-fat foods(Reference Finlayson, King and Blundell5), at baseline (1-month pre-surgery) and 3-months post-surgery. Explicit liking and wanting (conscious hedonic feelings/desire to consume) were measured using Visual Analogue Scales, whilst implicit wanting (unconscious motivational expression) was measured using food selection and reaction times in a forced-choice task.
There were no significant differences in food preferences between patients and controls at baseline. BMI for controls remained stable (+0·1 ± 1·3 kg/m2, p = 0·73), whilst BMI in patients significantly decreased (−8·3 ± 2·7 kg/m2, p = <0·01). GB patients expressed a significant decrease in the explicit liking (F(1,33) = 10·42, p = 0·03), explicit wanting (F(1,33) = 5·76, p = 0·02) and implicit wanting (F(1,33) = 4·92, p = 0·03) for sweet foods after surgery. However, there were no significant changes in preferences for high-fat foods in patients from pre to post-surgery. There were no significant changes in preferences for controls for sweet or high-fat foods.
In conclusion, patients express a significant decrease in preferences for sweet foods post-surgery. As changes in implicit unconscious motivational expression of food preferences may be more predictive of actual food consumption(Reference Pool and Sennwald6) these findings highlight a possible mechanism responsible for the success of GB as an obesity treatment.