The increasingly convoluted relationship of appetite and obesity has recently been suggested by Lowe and Butyrn (2007) to be partially mediated by a mechanism referred to as “hedonic hunger,” or the craving for foods in the absence of energy needs. As gastric bypass surgery results in several neurobiological changes that may impact hedonic hunger, data in this population as well as obese subjects who have not undergone the surgery were collected in a recent study by Schultes, Ernst, Wilms, Thurnheer, and Hallschmid (2010). Their work compared subjective hedonic hunger between these and nonobese subjects to evaluate the influence from obesity and gastric bypass surgery and test the hypothesis that hedonic hunger may be a factor in the etiology of obesity.
The three groups involved in the cross-sectional study consisted of a control group of 110 nonobese subjects with an average BMI (in kg/m2) of 22.4, 123 severely obese subjects with an average BMI of 45.1, and 136 overweight and obese subjects who underwent gastric bypass surgery at least one year prior to enrollment with an average BMI of 29.5. To measure hedonic hunger, the Power of Food Scale (PFS), which contains 15 questions on a 5-point scale divided into three domains (food readily available in the environment but not physically present (“food available”), food present but not tasted (“food present”), and food when first tasted but not consumed (“food tasted”)) was utilized. The average of the 15 scores yielded an aggregate domain score, as well as averages of each of the three domains. Of the gastric bypass subjects, 58 underwent an interview rating eating-related symptoms also on a 5-point scale. Statistical analysis measured differences across groups and associations between PFS scores and the characteristics of subjects.
The mean overall PFS score for severely obese (2.8 ± 0.9) was significantly higher than the nonobese (2.3 ± 0.7) and gastric bypass (2.2 ± 0.7). In the separate “food available” domain, severely obese (2.6 ± 1.0) were significantly higher than both nonobese (1.9 ± 0.8) and gastric bypass (2.0 ± 0.7), and in the “food present” domain, severely obese (3.0 ± 1.0) were also significantly higher than nonobese (2.3 ± 0.9) and gastric bypass (2.1 ± 0.9). Both severely obese (3.0 ± 1.0) and nonobese ( 2.9 ± 0.9) were significantly higher than the gastric bypass ( 2.6 ± 0.9) for the “food tasted” domain score. These data suggest that the severely obese had an increased hedonic hunger compared to gastric bypass and nonobese subjects. Both severely obese and nonobese rated higher than gastric bypass in the individual “food tasted” domain, reflecting a reduction in the taste element of hedonic hunger from surgery but not an increase from severe obesity. PFS scores in the “food available” and “food present” domains for gastric bypass were inversely correlated with excess BMI loss % (-0.182 and -0.172), suggesting that these patients who had the lowest scores had the largest reduction in BMI. The additional testing for eating-related symptoms in the gastric bypass subgroup showed that early dumping symptoms were significantly inversely correlated with the aggregated domain score, “food present,” and “food tasted” scores. This may indicate a learned aversion to high reward foods which cause this in some patients.
Gastric bypass subjects were not given the PFS test prior to their surgery, thus it is possible that their PFS scores were low at that point and not the result of surgery. This however is unlikely as bypass subjects had their operations in the authors’ department, and the non-bypass severely obese subjects were being evaluated for surgery also in their department. It is possible that both groups, who were motivated to seek treatment, do not reflect characteristics of the general population.
This study corroborates previous findings by Cappelleri et al. (2009) who validated the relationship between BMI and PFS scores in 2 data sets. The results do not directly provide a mechanism by which gastric bypass surgery reduces hedonic hunger. However, as reviewed by Ashrafian and le Rouxother (2009), research has shown that surgery increases gastrointestinal satiety hormone secretion, which may influence neuroregulatory mechanisms governing food reward behavior. Existing research has led to the distinction of two components of food reward: “wanting” and “liking,” and that obese subjects are enhanced in the former (Mela 2006). The results by Schultes et al. (2010) corroborate as the PFS scores reflect an increased “wanting” in severely obese subjects compared to nonobese subjects in the relevant domains (“food available” and “food present” but not “food tasted”). Gastric bypass subjects mirrored these results except for the “food tasted” domain in which they were reduced compared to both severely obese and nonobese, suggesting surgery also reduces the “liking” of palatable foods.
Hedonic hunger is increased in severely obese subjects compared to nonobese and gastric bypass subjects. This suggests surgery reduces the increased food reward associated with obesity and warrants additional research for potential therapeutic treatment. In particular, a prospective study is needed to follow gastric bypass patients before and after their surgeries, and confirming the involvement of gastrointestinal satiety hormones throughout the changes in hedonic hunger is paramount.
Edit: this study found that altered meal frequencies affect hedonic hunger without affecting energy intake, and thus could play a factor as gastric bypass would likely change frequency.
Ashrafian, H., & le Roux, C. (2009). Metabolic surgery and gut hormones – A review of bariatric entero-humoral modulation Physiology & Behavior, 97 (5), 620-631 DOI: 10.1016/j.physbeh.2009.03.012
Cappelleri, J., Bushmakin, A., Gerber, R., Leidy, N., Sexton, C., Karlsson, J., & Lowe, M. (2009). Evaluating the Power of Food Scale in obese subjects and a general sample of individuals: development and measurement properties International Journal of Obesity, 33 (8), 913-922 DOI: 10.1038/ijo.2009.107
Lowe, M., & Butryn, M. (2007). Hedonic hunger: A new dimension of appetite? Physiology & Behavior, 91 (4), 432-439 DOI: 10.1016/j.physbeh.2007.04.006
Mela, D. (2006). Eating for pleasure or just wanting to eat? Reconsidering sensory hedonic responses as a driver of obesity Appetite, 47 (1), 10-17 DOI: 10.1016/j.appet.2006.02.006
Schultes, B., Ernst, B., Wilms, B., Thurnheer, M., & Hallschmid, M. (2010). Hedonic hunger is increased in severely obese patients and is reduced after gastric bypass surgery American Journal of Clinical Nutrition, 92 (2), 277-283 DOI: 10.3945/ajcn.2009.29007