This study offers new answers to pertinent questions of high individual and societal relevance: Which body weight is viewed as ideal? Which range of body weight is socially accepted? Who is seen as “too thin” and who is seen as “too heavy”?
Previous answers to these questions mainly relied on non-representative data collected from mass media, convenience samples, and ethnographic sources, concluding that social body weight norms in modern societies are strict and thin. The notions of a “strict” and “thin” social body weight norm remain largely unquestioned in the research literature and have become firmly entrenched in the media and in the public discourse.
Our representative population data allowed us to examine if the notion of a strict thinness norm accurately reflects beliefs and expectations held in the general population: Is it true that social body weight norms are strict, allowing for only a narrow range of socially accepted body weight? And is it true that social body weight norms are thin, endorsing body ideals that are very slender and possibly underweight?
Our answer to the first question is yes, but our answer to the second question is no. Hence, our main conclusion is that social body weight norms are strict but not thin. This conclusion applies for female and male raters, for female and male bodies, in all age groups, and in all countries. The prominent notion of a very thin female ideal is not supported by population-based data. The probability of selecting very slender and underweight figures as female ideals is small in all countries and in all subgroups studied. The range of female figures considered by a majority as not too thin but also not too heavy, however, was narrow: Not only underweight but also slender female figures at the lower bound of normal BMI are commonly rated as “too thin”; not only very heavy or obese but also moderately overweight female figures are commonly rated as “too heavy.” This means that although the notion of a thin norm is not supported, the notion of a strict norm on female body weight is supported at population level.
For norms governing male body weight, results are similar regarding the uncommonness of thin ideals. A notable difference is that social body weight norms are less strict for men than for women. In all countries and all subgroups studied, norms for ideal and accepted body weight are less strict for male bodies.
Considering the contrast between our results and the results of previous research based on non-representative samples, we find that a key descriptive conclusion – namely the central tendency of “thin” social body weight norms – does not replicate in representative samples. Several relational conclusions from previous research, however, do replicate: men’s female ideal is heavier than women’s female ideal; social body weight norms are stricter for women than for men; and social body weight norms are thinner and stricter for younger age groups.10, 32, 33, 34 The contrast between convenience-sampled data and population-representative data found in our study is consistent with findings from survey methodology, showing that in non-representative samples, descriptive distributions are often biased, whereas relational conclusions about two or more variables are often robust.17
However, our results are only partially consistent with the idea that bias towards younger and slenderer participants in samples used by earlier research is mainly responsible for the discrepancy in the findings. First, although we indeed found thinner social body weight norms among younger respondents and respondents with lower levels of BMI, figures representing very thin or underweight types were not considered ideal or accepted by the majority of young and slender respondents. Second, if very thin ideals found in previous studies had mainly resulted from sampling bias towards slenderer respondents, we would expect a different pattern of cross-national results than observed in the present study. Most notably, the US and Germany barely differed in their social body weight norms despite substantial population differences in body weight. Similarly, we found the heaviest social body weight norms in the Netherlands although this population is the thinnest among the three. These results suggest that cultural factors may still play an important role, next to own weight and beyond the social comparison mechanism.
Previous evidence was not only based on convenience samples but also on relatively old data collected in the 1990s and early 2000s. Changes since then are not limited to the continued spread of overweight and obesity. Cultural representations of beauty may also have changed. Studies speculate that recent social movements towards body acceptance may have led to more heterogeneous cultural ideals in the media.19, 35 Future population-based research should introduce more variation in cultural factors next to variation in population body weight as well as direct measures of cultural factors to understand why social body weight norms vary between societies.
Even though social body weight norms are not thin in any of the (sub)populations of this study, our findings demonstrate that people perceive body weight norms to be thinner than they are. The contrast between what people believe – actual body weight norms and what people believe others believe – perceived body weight norms is crucial to understand social body weight norms and their potential consequences for individuals. This contrast was most pronounced in the U.S. and concentrated in questions about the ideal female body weight.
We cannot explain the discrepancy between actual and perceived body weight norms with our data, but the evidence is suggestive: The ubiquitous notion of a strict thinness norm governing body weight ideals, and especially ideals about female bodies, may influence people’s perception. Even if a strict thinness norm is not real, it might be still perceived as real by many and therefore entail real consequences, as stipulated by the Thomas theorem.36 This applies particularly to the perception of a strict thinness norm on female body weight in the U.S. If women perceive this norm as real, it may entail consequences for the risk of eating disorders, body dissatisfaction and psychological distress. However, we note that although differences between the actual body weight norms and perceived body weight norms were substantial, only a minority – albeit substantial in size – perceived very slender or underweight-looking figures as “most people’s ideal.”
Our results demonstrate the relevance and contribution of population-based research on social body weight norms to establish a representative baseline against which the dominant narrative can be evaluated. Our findings question this narrative and call for further population-based research to improve our understanding of social body weight norms, their representation in the media, and their perception in the public. An improved scientific understanding of social body weight norms can potentially reduce harmful consequences, in particular those associated with biased perceptions of a thinness norm that may not be real.