Generally, individuals prefer to continue living and aging in a familiar region (1, 2). The idea of “aging in place” represents a central concept of community living (3, 4). Aging in place gives older adults a sense of identity through human relationships, roles, and independent living (5). However, factors such as proximity to disaster zones affect aging in place. Taking measures to facilitate aging in place following such events is an important public health concern.

In Japan, natural disasters occur frequently, and after each disaster, evacuees emerge. A large majority of evacuees settled down in their new residences; however, after the Fukushima Daiichi nuclear power plant accident that occurred in 2011, evacuated residents experienced major changes in their lifestyle and social environment. Currently, more than 30,000 people who evacuated a radioactive atmosphere are still living in temporary housing. Consequently, the effects of such evacuation on the health of residents are multifaceted and long-term (6). For example, evacuees experience severe levels of depression (7), and the number of evacuees that require nursing care services increases (8, 9). Furthermore, worsening health indicators, including an increase in hypertension and diabetes as well as a sharp increase in the number of individuals with obesity (10, 11), have been observed. However, since the evacuation order has been lifted, only a few studies have examined aging in place, specifically the differences in the health status between residents who returned to their original locations and those who did not, which remains insufficiently evaluated.

Katsurao Village is located within a 20–30 km radius of the Fukushima Daiichi nuclear power plant (Figure 1). In 2011, at the time of the nuclear accident, the village had a population of ~1,500 individuals, and following the radioactive incident, all residents were forced to evacuate. In June 2016, the radiation levels declined, and evacuation orders were lifted for most parts of the village. Seven years have passed since the residents could return, and in November 2023, 464 people were living in the village. However, more than 60% of the village's registered population still have not returned.

Following the nuclear accident, obesity has increased among registered residents of Katsurao Village. Nevertheless, no studies focusing on the evacuation of residents after the nuclear accident in Chornobyl and the subsequent increase in obesity have been found. However, obesity is related to various diseases, including type 2 diabetes (12), and places a considerable burden on healthcare expenditure (13). Therefore, from a public health perspective, it is important to understand the factors underlying the obesity trends observed in this region and implement measures to prevent obesity.

This study aimed to determine the prevalence of obesity among residents of Katsurao Village, Fukushima Prefecture, after the evacuation order was lifted in 2016 and compare the prevalence of obesity by place of residence (inside or outside the village) (14).

Here, we reported the effects of long-term evacuation following a radioactive disaster on the development of health risks in the affected population over a long period. The effects of long-term relocation on health after natural disasters (18) have been previously demonstrated after radiation disasters (19).

Relocation and living outside the village were significantly associated with obesity. Generally, various factors contributed to the increase in BMI in this population. Although not significant from the items in this study, changes in the living environment and new lifestyle habits, such as in eating and exercise (20, 21), lead to an increase in BMI. From our observations of the living conditions of our residents, the lower BMI in residents who returned to the village may be attributed to a resumption of their daily lives eating and exercise habits. Typically, the individuals in the village engage in agricultural activities.

Obesity should be considered among the factors leading to the rapid increase in the number of people certified for long-term care in formerly evacuated areas following the nuclear accident, including Katsurao Village (22). A significant association exist between obesity and frailty (23). Radioactive-affected areas are experiencing population displacement and an aging population (24), making long-term care an urgent issue (25). Interventions to prevent obesity in individuals from the affected areas could address the social challenges of long-term care in this region.

It is important to consider obesity as a long-term health problem following a radiation disaster. The obesity rate has consistently been higher among people living outside the village. Losing weight for individuals with obesity requires time and effort, and exercises are more challenging to complete if an individual is obese. Conventional support for residents should be based on their actual living conditions. However, when nearly 70% of registered residents live outside the village, it is difficult for the municipal office to take the lead in continuing resident support (26). Our results suggest that sharing information with health institutions and health-related organizations in evacuation destinations and providing early intervention to address anticipated health risks are necessary.

This study has some limitations. First, the data collected was from a small village, and the sample size was small. Second, this study examined only BMI data. Further research is needed to determine other health-related factors among affected individuals in the village and surrounding areas affected by evacuation. Third, the medical examination item “place of residence” may not accurately reflect the evacuee/returnee status. After more than 10 years since the nuclear accident, it may no longer be possible to categorize those living outside the village as “evacuees” and those living within the village as “returnees.” Therefore, in the future, there will be a need for interventions to address health issues that consider the inflow and outflow of populations.

This study tracked the health status of residents over a long period until 2023, 12 years after the nuclear accident. The health effects of long-term evacuation on residents can be demonstrated as the risk factors for obesity, specifically BMI. Obesity is a health issue faced by residents transitioning to new lifestyles, and countermeasures are indispensable. When implementing community health promotion after a disaster, it is necessary to consider interventions immediately after the disaster occurs.

The original contributions presented in the study are included in the article/Supplementary material, further inquiries can be directed to the corresponding author.

NI: Writing – original draft, Writing – review & editing. MTa: Conceptualization, Writing – review & editing. NM: Conceptualization, Methodology, Writing – review & editing. IA: Conceptualization, Data curation, Methodology, Writing – review & editing. AF: Conceptualization, Investigation, Writing – review & editing. HS: Investigation, Methodology, Writing – review & editing. TA: Conceptualization, Investigation, Writing – review & editing. CY: Conceptualization, Investigation, Writing – review & editing. MS: Conceptualization, Writing – review & editing. TZ: Data curation, Writing – review & editing. MTs: Supervision, Writing – review & editing.