A new study published in Japanese Psychological Research suggests that Japanese men judge female body attractiveness far more by waist-to-bust ratio than by the widely cited waist-to-hip ratio. The findings challenge the long-standing evolutionary psychology claim that a specific hip-focused body proportion represents a universal standard of beauty.
The research was led by Tomohiro Suzuki of Wayo Women’s University, an expert in the psychology of clothing and appearance. Suzuki set out to examine whether widely accepted claims about ideal female body proportions still hold when body models and measurement methods are tailored to a specific culture.
According to Suzuki, beauty standards change considerably across historical periods and societies, affecting not only fashion and cosmetics but also preferred body shapes. Although evolutionary theories suggest certain proportions may signal youth and fertility, cultural influences and media exposure can strongly shape perceptions of attractiveness.
Why these body ratios matter
Two body ratios dominate research on female attractiveness: waist-to-hip ratio and waist-to-bust ratio. Both are calculated by dividing waist circumference by either hip or bust circumference, with lower values indicating a narrower waist relative to the other measurement.
In many Western studies, a waist-to-hip ratio of 0.7 has been presented as an almost universal ideal. Evolutionary psychologists have argued that an hourglass figure may signal youth, low parity and reproductive health, potentially influencing mate preferences across cultures.
However, Suzuki’s team noted that many earlier experiments relied on simplified drawings or crude image editing. By stretching or narrowing bodies from a single frontal view, these methods could distort natural body proportions and make it difficult to distinguish genuine shape preferences from reactions to overall body size.
Building culturally realistic body models
To overcome these limitations, the researchers created body silhouettes using actual anthropometric data collected from Japanese women in their twenties by a clothing company. They first generated three-dimensional body models before converting them into two-dimensional outlines to preserve realistic proportions.
All figures were standardized to a body mass index between 20 and 22, representing a typical healthy range. This allowed the researchers to isolate the influence of body shape without introducing differences in thinness or body weight.
The models included four waist-to-hip ratios and four waist-to-bust ratios—0.6, 0.7, 0.8 and 0.9 for each measurement. Combining these values produced 16 different silhouettes while keeping overall body size constant.
How the study was conducted
The study involved 398 Japanese men between the ages of 20 and 59. Participants were distributed relatively evenly across age groups, with an average age of approximately 40 years.
Each participant viewed all 16 silhouettes in random order and rated them using a six-point scale for two separate dimensions: aesthetic attractiveness, reflecting general visual appeal, and sexual attractiveness, reflecting physical desirability.
The researchers intentionally distinguished between these two forms of attractiveness to determine whether beauty and sexual appeal were judged differently. In practice, however, the two ratings were often closely related.
Waist-to-hip ratio had little influence
Contrary to much of the previous Western literature, differences in waist-to-hip ratio had almost no meaningful impact on how Japanese men rated the silhouettes.
Changing the ratio from 0.6 to 0.9 did not produce statistically significant differences in either aesthetic or sexual attractiveness.
These findings directly challenge the widely held belief that a waist-to-hip ratio of 0.7 represents a universal standard of female attractiveness.
Instead, the researchers suggest that the emphasis placed on hip proportions may partly reflect Western beauty standards and methodological limitations in earlier studies.
Suzuki described the finding as surprising, given the influence the 0.7 waist-to-hip concept has had within evolutionary psychology. The results highlight the importance of examining body preferences across different cultural populations.
Waist-to-bust ratio drove attractiveness ratings
The waist-to-bust ratio produced a much stronger and more consistent pattern.
Across every male age group, silhouettes with waist-to-bust ratios of 0.6 and 0.7 received the highest ratings for both aesthetic and sexual attractiveness.
As the ratio increased to 0.8 and 0.9, attractiveness scores declined substantially. For aesthetic attractiveness, the difference between ratios of 0.7 and 0.8 represented a moderate effect size, indicating a clear shift in preference rather than a minor statistical difference.
Sexual attractiveness showed a similar pattern. Ratios of 0.6 and 0.7 remained the most attractive, with 0.6 receiving slightly higher average ratings.
Overall, the relative size of the bust compared with the waist proved to be the strongest body characteristic influencing participants’ judgments.
Media, rarity and cultural influence
The preference for a waist-to-bust ratio of 0.6 also illustrates how modern beauty ideals can differ from naturally common body proportions.
For a woman with a 65-centimeter waist, achieving a ratio of 0.6 would require a bust circumference of approximately 108 centimeters—a combination that is exceptionally uncommon among Japanese women.
Because such proportions rarely occur naturally, the researchers suggest that environmental influences may contribute to shaping these preferences.
In Japan, women portrayed in anime, manga and digital media are often depicted with exaggerated bust-to-waist proportions, potentially influencing perceptions of what appears attractive or even normal.
The findings also fit broader cultural patterns in Japan, where beauty standards have historically emphasized slimness more than pronounced curves. At the same time, relatively smaller buttocks are often preferred compared with some Western and Latin American beauty ideals, which may further reduce the importance of hip size in attractiveness judgments.
Limitations and future research
The authors caution that their findings apply only to body silhouettes within a relatively narrow, healthy BMI range.
Preferences may differ for substantially thinner or heavier bodies, as previous research suggests body weight and body shape interact in complex ways when influencing attractiveness.
The study also focused exclusively on men evaluating women’s bodies. It does not address how Japanese women evaluate female bodies, perceive their own appearance or judge male physiques.
Future research could apply the same realistic modeling approach to women participants and to body models representing different ethnic groups. Such comparisons may help determine which attractiveness preferences reflect shared biological tendencies and which are primarily shaped by cultural influences and media exposure.
Suzuki says he hopes to continue exploring how people evaluate appearance and manage their own looks in everyday life. By refining research methods and incorporating cultural context, he believes scientists can better understand how body ideals influence self-image and psychological well-being.
