'When hunger makes everything better looking!': The effect of hunger on the aesthetic appreciation of human bodies, faces and objects

Hunger is a potent homeostatic drive influencing behavior, cognition, and decision-making. Previous research suggests a link between hunger and preferences for body weight, particularly in men rating women's bodies. The "Insurance Hypothesis" posits that hunger leads to a preference for rounder figures as a protective mechanism against food scarcity. However, findings have been inconsistent, with some studies failing to replicate the effect and others questioning the body-specificity of this phenomenon. This study aims to address these inconsistencies by employing a within-subject design, comparing aesthetic judgments under fasting and post-snack conditions in both men and women. The inclusion of faces and non-corporeal objects (vases) allows for testing the domain-specificity of hunger's influence on aesthetic preferences. The study also accounts for individual differences in BMI, a factor known to affect hunger perception and body image.

Existing research on the impact of hunger on aesthetic preferences is mixed. Some studies indicate that hungry men prefer heavier women, potentially due to the association of body weight with fertility and resourcefulness. The "Insurance Hypothesis" proposes that hunger prompts a preference for rounder bodies as a safeguard against future food shortages. However, a randomized controlled trial failed to replicate this effect, suggesting potential confounding factors like alcohol consumption. Other research examined the impact of hunger on preferences for non-food objects, yielding inconsistent results. Some studies found hunger increased the desire to acquire but not necessarily the liking of non-food items, whereas others showed a preference for larger objects in hungrier participants. These inconsistencies highlight the need for a well-controlled study examining the effect of hunger on aesthetic judgments across different stimulus categories, considering individual differences in BMI.

Forty-four participants (21 women, mean age 23.7 years) completed the study. Participants completed the aesthetic task on two separate days. On one day, they completed the task after at least 12 hours of fasting. On the other day, they completed the task immediately after consuming a controlled snack (bananas) following at least 12 hours of fasting. The order of conditions was counterbalanced. Stimuli included computer-generated images of slim and round bodies (faces scrambled), faces (hair removed), and vases. Participants rated the stimuli's attractiveness using a 10 cm visual analog scale (VAS). BMI and subjective hunger ratings (VAS) were also collected. A 2 (fasting/snack) x 3 (body/face/object) x 2 (round/slim) repeated measures ANCOVA was conducted with BMI and hunger ratings as covariates.

Overall, participants preferred slim stimuli to round stimuli. However, hunger led to higher liking ratings for round stimuli compared to post-snack conditions. This effect was observed across all stimulus categories (bodies, faces, and objects). The main effect of stimulus type was moderated by snack condition hunger ratings. Participants with high BMI showed a significant interaction between physiological status and size, preferring round stimuli more in the fasting condition. This effect was not observed in participants with low BMI. A significant bivariate correlation was found between BMI and the hunger-induced shift in aesthetic preference for all stimuli types.

The findings extend previous research by demonstrating that hunger's influence on aesthetic preferences is not limited to body images but also affects faces and inanimate objects. The observation that only high BMI participants showed a hunger-induced shift towards rounder stimuli suggests a potential moderating role of body adiposity. This could be explained by the "Insurance Hypothesis", where individuals with higher BMI might perceive greater food insecurity and thus exhibit a stronger preference shift for roundness. However, the finding that hunger affects the appreciation of objects challenges the strict interpretation of the Insurance Hypothesis and suggests a more general effect of hunger on the perception of abundance. The results might also be influenced by the observer's own BMI and the degree of their interoceptive awareness.

This study demonstrates that hunger influences aesthetic judgments of various stimuli, including bodies, faces, and objects. The effect is moderated by individual BMI, with individuals with higher BMI showing a more pronounced shift in preference toward rounder stimuli when hungry. Future research should investigate the mediating role of interoception, socio-economic status, and gender in these effects. Further investigation could also focus on specific features of stimuli beyond simple size and shape, potentially uncovering gender-specific preferences.

The study's limitations include the lack of explicit gender analysis (though self-identified gender was recorded), potential response biases from judging multiple stimulus categories on the same day, and the absence of direct assessment of socio-economic status. Future research should directly assess gender differences and separate the presentation of stimulus types to mitigate potential response biases.