Effects of Intermittent Fasting on Body Compositions Using Bioimpedance Analyzers

Abstract

Advancements in bioimpedance technology have enabled convenient tools such as smart scales for monitoring body composition. This study aimed to evaluate the accuracy of bioimpedance analyses using two types of bioimpedance analyzers (BIAs) during alternate day fasting (ADF). In this study, Bioimpedance Analyzer 450 (a professional-grade device) and the Mi Body Composition Scale (a consumer-grade device) were used to assess changes during a four-week ADF intervention. Six healthy participants, aged 20–30 years underwent ADF: Alternating between 500 kcal intake on fasting days and unrestricted eating on non-fasting days. Body fat percentage, lean mass, and total body water were measured before and after the intervention using both devices. The results showed no statistically significant changes across all parameters (p>0.05); however, the Biodynamics Analyzer detected +0.56% increment in the body fat and −0.56% decrement in the lean mass. While the Mi Scale showed −0.16% changed in the body fat and +0.13% in the lean mass. These discrepancies highlight the higher sensitivity of the professional-grade BIA in capturing subtle physiological changes. The total body water remained stable in both groups. The results suggest that although consumer-grade devices offer accessibility, they may lack the precision needed for detecting minor shifts during dietary interventions. This study emphasizes the importance of using validated tools in clinical and research settings. It also provides preliminary insights into the metabolic effects of ADF, including possible compensatory eating behavior on non-fasting days and minor fluid shifts. These findings underscore the limitations of consumer-grade BIAs in scientific monitoring and support further research to validate their use in long-term health tracking.