1. Social norms and diets for young women
with Yumi Ishikawa, Youngrok Kim, Mao Nakayama, and Ryo Sakamoto, Journal of the Japanese and International Economies, December 2026, 101450.
Abstract: Underweight among young women is a serious health issue in Japan, with more than 20% of women in their teens and twenties being underweight. A possible reason for this is the prevalence of social norms that dictate women should be thin for a beautiful appearance. This study investigates the effect of social norms on behaviors and attitudes toward dieting among young women by conducting online laboratory experiments at a private university in Japan. The experiments reveal that the vast majority of young women significantly overestimate the prevalence of dieting among women and the level of support for such behaviors within their university. Correcting misperceptions of these norms positively affects their attitudes toward dieting, yet no behavioral changes were observed. We bolster the external validity of our main findings using the results of an online survey with a larger national sample of women in their 20s, matched to the population distribution across prefectures of Japan. Correcting people’s misperceptions of social norms through education and advertising may effectively influence their attitudes toward healthy and balanced eating habits.

2. The cost of Internet use: An examination of the causal impact on body weight
with Miki Kohara, Journal of Evolutionary Economics, August 2026, 36(3), 64.
Abstract: Internet use is often regarded as a double-edged sword; while it offers access to new activities and information, it may also crowd out other beneficial activities because of time constraints. This paper investigates the effect of Internet use on health, with a particular focus on body weight, which is measured by the incidence of being overweight. The Internet condition in China has undergone tremendous development, providing an ideal context to evaluate the impact of Internet use. Utilizing individual panel data, we employ a fixed-effects instrument variable (FE-IV) strategy using the number of broadband access ports per capita as the instrument. The results show that Internet use significantly increases the probability of being overweight. The effect is more salient among males, younger generations, individuals with lower levels of education, and in the northern region. Further mechanism analysis suggests that Internet use is associated with reduced sleep quality and changes in other health-related behaviors in mixed ways, including greater junk food intake and more exercise. Our back-of-envelope calculations show that Internet-induced overweight may generate substantial medical costs. These findings reveal a hidden health cost of Internet use and call for greater public attention.

3. Sanitation and work time: Evidence from the toilet revolution in rural China
with Dongqin Wang, World Development, October 2022, 158, 105992.
Abstract: In 2020, 46% of the global population lacked safely managed sanitation services. Poor sanitation may lead to health problems and restrict economic activities. This study is the first to focus on the government-subsided Toilet Revolution in rural China and empirically investigates the causal effects of sanitation coverage increase on labor supply in developing countries. Using the China Health and Nutrition Survey data, we exploit the temporal and regional variation during the revolution and employ a difference-in-differences methodology. Our study finds that rural households with access to clean flush toilets significantly increase their work time by 0.253–0.431 h/day, and the effects are more prominent among women than men. As for the mechanism, clean toilets significantly decrease housework related to cleaning the house and raising livestock and poultry, allowing people to reallocate their time and invest more into work, which is more salient for women. Our findings highlight the importance of sanitation coverage in improving the economic outcomes in the rural areas of China. For policymakers concerned with the provision of sanitary facilities and the supply of labor force in developing countries, this study indicates that improved sanitation facilities also unexpectedly increase labor supply, particularly for women.

Employer Diversity Signals and Match Quality in Job Search
with Kotaro Fujisaki, Yumi Ishikawa, and Miki Kohara
Abstract: How does information about workplace diversity shape job application decisions and employer-employee match quality? We study this question using data from an international job fair where university students from Southeast Asia meet Japanese recruiting firms. Firms providing more information about workplace diversity in their presentations and brochures attract greater application interest. We construct a unique measure of match quality across firm-student pairs, including unrealized matches, and show that the effects of diversity information are stronger for higher-quality potential matches, where skill demand and supply are better aligned. These effects are driven by female job seekers, who display greater interest in diversity information, interpret it as a signal of better promotion prospects and a more productive workplace, and exhibit higher willingness to pay for gender-diverse workplaces. Diversity operates as a non-pay amenity valued particularly by women and can enhance match quality by altering applicant pool composition.

Peer Effects on Consumption: Evidence from China
Abstract: This study investigates peer effects on consumption by exploiting unique urban housing demolition (UHD) program in China. We study the consumption response of non-demolition households whose demolished peers have received substantial unexpected wealth and raised consumption. Our instrumental variable (IV) estimation shows that the elasticity of household annual consumption with respect to peers’ consumption is around 0.233 to 0.292. These effects are more prominent in counties with a higher proportion of demolition households and do not vary across community within a country. The findings imply a positive and significant externality of large-scale urban housing demolition on consumption.