Background: Despite the introduction of modern scales for assessing physical health, "body mass index" (BMI) remains a foundational metric in many health assessments. Objectives: This community-based cross-sectional study aims to compare BMI with bioelectrical impedance analysis (BIA) in evaluating the physical health of Iranian women of reproductive age. Methods: A descriptive cross-sectional study was conducted on 182 Iranian women aged 30 - 45 years, selected through random sampling from the population served by selected urban health centers. The Omron BF511 bioelectrical impedance analysis device was used to measure BMI, skeletal muscle mass, total body fat, and visceral fat. A structured questionnaire was also administered to collect sociodemographic data. Results: The average BMI of the participants was 27.47 kg/m², with skeletal muscle mass comprising 24.98%, visceral fat averaging 6.93%, and total body fat at 40.04%. When comparing BMI with total body fat, 52% of cases were misclassified; with visceral fat percentage, 68% were misclassified; and with skeletal muscle mass percentage, 73% were misclassified. Misclassification was most pronounced among individuals with a normal BMI who were overweight or obese according to body fat percentage. Conclusions: This study highlights the critical need to reassess the use of BMI as an accurate health indicator for women of reproductive age. The researchers argue that reliance on BMI as a sole health metric is outdated, emphasizing the need for a comprehensive reevaluation of health assessment criteria for women in this demographic.