Impact of Abdominal Obesity on Frailty Development: A Web-Based Survey Using a Smartphone Health App

Background/Objectives: Identifying adults at high risk of frailty and implementing appropriate interventions are critical for extending healthy life expectancy. This retrospective cohort study examined whether abdominal obesity predicts frailty progression over one year among 2962 community-dwelling adults aged 30–79 years in Osaka Prefecture, Japan. Methods: Data were collected from 2962 individuals (mean age, 62.7 ± 8.8 years) who completed annual surveys through a health application in both 2023 and 2024 and had available waist circumference data. Frailty was assessed using the Kihon Checklist. Logistic regression analysis was performed to identify predictors of frailty progression. Results: At baseline (2023), 23% of participants had abdominal obesity, and 18% were categorized as frail. Among 2431 participants who were non-frail at baseline, the incidence of frailty after one year was significantly higher among those with abdominal obesity than those without (10.5% vs. 7.2%, p = 0.011). However, in the multivariate logistic regression analysis, frailty awareness (“know well” vs. “do not know,” adjusted odds ratio [aOR] = 0.341, 95% confidence interval [CI] 0.212–0.548), regular exercise habits (aOR = 0.596, 95% CI 0.382–0.930), and prefrailty status (aOR = 1.767, 95% CI 1.602–1.950) were significant predictors of frailty development, whereas abdominal obesity was not independently associated with frailty progression after adjustment. Conclusions: Although abdominal obesity was associated with frailty onset in crude analyses, this association became non-significant after adjustment. Greater frailty awareness and regular exercise appear to reduce the risk of frailty development, suggesting that lifestyle education and public awareness initiatives may help mitigate the impact of abdominal obesity on frailty progression.