Facial affective reactions to bitter-tasting foods

24 Differences in food consumption among body-weight statuses (e.g., higher fruit intake 25 linked with lower body mass index (BMI) and energy-dense products with higher BMI) has 26 raised the question of why people who are overweight or are at risk of becoming overweight eat 27 differently from thinner people. One explanation, in terms of sensitivity to affective properties of 28 food, suggests that palatability-driven consumption is likely to be an important contributor to 29 food intake, and therefore body weight. Extending this approach to unpalatable tastes, we 30 examined the relationship between aversive reactions to foods and BMI. We hypothesized that 31 people who have a high BMI will show more negative affective reactions to bitter-tasting 32 stimuli, even after controlling for sensory perception differences. Given that hedonic reactions 33 may influence consumption even without conscious feelings of pleasure/displeasure, the facial 34 expressions were included in order to provide more direct access to affective systems than 35 subjective reports. Forty adults (28 females, 12 males) participated voluntarily. Their ages 36 ranged from 18 to 46 years (M=24.2, SD=5.8). On the basis of BMI, participants were classified 37 as low BMI (BMI<20; n=20) and high BMI (BMI>23; n=20). The mean BMI was 19.1 for low 38 BMI (SD=0.7) and 25.2 for high BMI participants (SD=1.8). Each subject tasted 5 ml of a 39 grapefruit juice drink and a bitter chocolate drink. Subjects rated the drinks' hedonic and 40 incentive value, familiarity and bitter intensity immediately after each stimulus presentation. The 41 results indicated that high BMI participants reacted to bitter stimuli showing more profound 42 changes from baseline in neutral and disgust facial expressions compared with low BMI. No 43 differences between groups were detected for the subjective pleasantness and familiarity. The 44