Body dissatisfaction mediates the relationship between BMI and social avoidance. Body dissatisfaction refers to negative emotional experiences related to one’s physical appearance, such as distorted perceptions of body shape or excessive preoccupation with weight (Brechan & Kvalem, 2015; Zhang et al., 2024). In contemporary Chinese culture, social media has amplified the slim-body ideals represented by trends such as the “A4 waist” (a waist as narrow as an A4 sheet of paper), “peach hips” (round and lifted hips), and “chopstick legs” (extremely slim legs). Female college students who are frequently exposed to these idealized body images are more likely to engage in upward social comparisons, which can lead to a stronger fixation on having a low BMI and increased, ongoing body dissatisfaction. Sociocultural theory posits that cultural beauty standards shape individuals’ body image through processes such as social comparison and internalization (Heinberg et al., 1999; Zhang et al., 2024). Based on this theory, a higher BMI may make it harder for female college students to match the thin ideal emphasized by media, which can increase their likelihood of experiencing body dissatisfaction (Porras‐Garcia et al., 2020; Zhang et al., 2022). When female college students develop negative beliefs such as “I don’t look good enough” or “Others will judge me,” they are more likely to avoid social interactions to reduce the possibility of negative evaluation. Therefore, body dissatisfaction can be viewed as a key psychological process through which BMI influences social avoidance.

Self-esteem, another critical factor, has been identified as a key mediator in the relationship between BMI and social avoidance. Existing research has shown that BMI is negatively associated with self-esteem (Pilafova et al., 2007), and a 26-year longitudinal study further found that higher and increasing BMI among young females was associated with lower and slower-growing self-esteem (Kiviruusu et al., 2016). Self-Determination Theory suggests that self-esteem tends to be lower when it is built on malleable attributes such as physical appearance (Crocker et al., 2003). Consequently, college students whose self-esteem is tied to physical attributes like weight or height tend to exhibit lower self-esteem. Moreover, self-esteem has also been found to significantly and negatively predict social avoidance (Guo & Wu, 2021; Shang et al., 2025), with lower self-esteem female students more likely to avoid social situations due to concerns about negative evaluation (Yousaf, 2015).

Furthermore, body dissatisfaction is an important determinant of self-esteem. Prior studies have shown that body dissatisfaction is significantly associated with lower self-esteem (Porras‐Garcia et al., 2020) and can negatively predict girls’ self-esteem (Paxton et al., 2006; Yu & Liu, 2019). According to the theoretical model proposed by Fernández-Bustos et al. (2019), objective physical characteristics such as BMI affect psychological adaptation and behavioral outcomes through their impact on body dissatisfaction and subsequent self-concept. Accordingly, BMI can be viewed as a key objective physical indicator, with higher BMI often triggering more negative evaluations of one’s appearance and body shape, which in turn lowers self-esteem. Based on these findings, female college students with higher BMI are more likely to experience body dissatisfaction, which may lead to more negative self-evaluations and reduced self-esteem. Lower self-esteem, in turn, may increase social avoidance due to heightened concerns about negative evaluation. Thus, female college students with higher BMI may become trapped in a cycle of “body dissatisfaction–low self-esteem–high social avoidance”, which not only undermines social support but also poses risks to mental health.

The study aimed to explore the mediating role of body dissatisfaction and self-esteem between BMI and social avoidance. The following hypotheses were tested in the study:

Hypothesis 1: Body dissatisfaction mediates the relationship between BMI and social avoidance, such that higher BMI is associated with greater body dissatisfaction, leading to higher social avoidance.

Hypothesis 2: Self-esteem mediates the relationship between BMI and social avoidance, such that higher BMI is associated with lower self-esteem, leading to higher social avoidance.

Hypothesis 3: Body dissatisfaction and self-esteem play a serial mediating role in the association between BMI and social avoidance, such that higher BMI increases body dissatisfaction, which subsequently reduces self-esteem and leads to greater social avoidance.

A total of 669 (see Table 1 for characteristics). Participants included freshmen, sophomores, and juniors, representing majors such as arts, education, management, engineering, and social sciences.

The study was approved by the Research Ethics Committee of the School of Educational Science, Neijiang University, and all procedures adhered to ethical guidelines. Participation consented to the study with assurances voluntariness and confidentiality. They completed the survey on the Wenjuanxing platform (https://www.wjx.cn/).

Data were entered and analyzed using SPSS 23.0. Harman’s single-factor test was conducted to assess common method bias (using the standard 40% threshold), followed by descriptive statistics and correlation analyses. Mediation effect analysis was conducted using Model 6 of the PROCESS 3.3 macro plugin in SPSS (Hayes, 2013), with 5000 repeated bootstrap samples to calculate 95% confidence intervals.

To assess potential common method bias, Harman’s single-factor test was conducted. All items from the Body Image States Scale, Self-Esteem Scale, and Social Avoidance and Distress Scale were subjected to exploratory factor analysis. In the unrotated factor solution, six factors had eigenvalues greater than 1, with the first factor accounting for 25.41% of the variance, which is below the critical threshold of 40% (Podsakoff et al., 2003). Thus, no significant common method bias was detected in this study.

Participants ranged in age from 17 to 22 years, with height ranged from 145 to 182 cm (M = 160.45, SD = 5.57 cm) and weights ranged from 34 to 86 kg (M = 52.09, SD = 7.67 kg). Participants’ self-reported BMI ranged from 12.82 to 33.30 kg/m² (M = 20.25, SD = 2.96). Based on the BMI thresholds outlined in the National Student Physical Health Standard for female college students, 8.07% were classified as underweight (BMI ≤ 17.1), 81.47% as healthy weight (17.2 < BMI < 23.9), and 10.46% as overweight or obese (BMI ≥ 24.0).

Correlation analyses revealed significant associations among the study variables. BMI was negatively correlated with self-esteem (r = −0.18, p < 0.001) and positively correlated with both body dissatisfaction (r = 0.29, p < 0.001) and social avoidance (r = 0.34, p < 0.001). Self-esteem was negatively correlated with both body dissatisfaction (r = −0.50, p < 0.001) and social avoidance (r = −0.45, p < 0.001), while body dissatisfaction was positively correlated with social avoidance (r = 0.40, p < 0.001). No significant correlations were found between age and any of the study variables. The means, standard deviations, and correlation matrix for all variables are presented in Table 2.

BMI was specified as the independent variable, social avoidance as the dependent variable, and body dissatisfaction and self-esteem as mediators to evaluate their mediating roles. The VIF values for body dissatisfaction, self-esteem, and social avoidance were 1.09, 1.41, and 1.34, respectively, and all tolerance values were greater than 1, indicating no multicollinearity concerns. Regression analyses revealed that when BMI, body dissatisfaction, and self-esteem were simultaneously included as predictors of social avoidance, BMI significantly and positively predicted social avoidance (standardized regression coefficient β = 0.23, p < 0.001), body dissatisfaction significantly and positively predicted social avoidance (β = 0.17, p < 0.001), and self-esteem significantly and negatively predicted social avoidance (β = −0.33, p < 0.001). These results are summarized in Table 3.

The significance of the mediating effects was tested using the bias-corrected percentile bootstrap method with 5000 resamples. The mediating effect of body dissatisfaction was significant (β = 0.05), with a 95% confidence interval (CI) of (0.03, 0.08), accounting for 14.71% of the total effect. Thus, Hypothesis 1 was supported. The mediating effect of self-esteem was not significant (β = 0.01), with a 95% CI of (−0.01, 0.04), accounting for 2.94% of the total effect. Therefore, Hypothesis 2 was not supported. These results are summarized in Table 4.

Chain mediation effects as shown in Table 4 and Figure 1, the chain mediating effect of body dissatisfaction and self-esteem between BMI and social avoidance was significant (β = 0.05), with a 95% confidence interval (CI) of (0.03, 0.07), accounting for 14.71% of the total effect. Therefore, Hypothesis 3 was supported.

The mediation analysis confirmed that body dissatisfaction and self-esteem mediate the relationship between BMI and social avoidance, with a total indirect effect of β = 0.11, accounting for 32.35%. The total indirect effect comprises two significant pathways: one through body dissatisfaction alone (β = 0.05, 14.71%) and another serially through body dissatisfaction and self-esteem (β = 0.05, 14.71%).

This study has several limitations. First, the cross-sectional design limits the ability to establish causal relationships between variables. It is also possible that higher social avoidance reduces physical activity opportunities, potentially contributing to BMI increases over time. Future longitudinal studies are needed to validate these findings and to examine the potential bidirectional relationship between social avoidance and BMI. Second, only 8.07% of the female college students in this study were classified as underweight (BMI ≤ 17.1), which may limit the representativeness and generalizability of findings for this subgroup. Whether these findings can be generalized to underweight female college students warrants further investigation. Moreover, other psychosocial mechanisms such as fear of negative evaluation, rejection sensitivity, and internalized weight bias may also shape social avoidance and warrant examination in future research. In addition, the Weight Stigma Exposure Inventory (WeSEI) provides a new perspective for assessing how environmental factors (such as media content) contribute to individuals’ awareness of weight stigma (Çarkıt et al., 2025). Future research may explore how such environmental cues interact with BMI and body dissatisfaction to ultimately influence social avoidance. Finally, interventions based on Cognitive Behavioral Therapy (CBT) have been shown to effectively improve women’s body image satisfaction (Zamiri-Miandoab et al., 2021). Future studies could explore whether CBT-based body image interventions can enhance self-esteem and reduce social avoidance.