Background: Resistance training (RT) has been established as the most efficient approach for lean body mass maintenance required for preserving a sufficiently high metabolism during weight loss. Objective: This study aimed to evaluate the impacts of the ketogenic diet (KD) and regular diet (RE) in combination with 8-week resistance exercise (RT), on body weight, body fat mass (BFM), and lean body mass (LBM) of untrained individuals. Methods: Twenty untrained participants were randomly assigned to the RE+RT and KD+RT as control and experimental groups, respectively. Sixty to ninety minutes of diversified resistance exercise were performed by both groups, three sessions weekly, and diet was self-administered with a recommended daily energy and protein intakes. Body composition was measured using a Bioelectrical Impedance Analyzer. One-way Analysis of Covariance (ANCOVA) was applied to analyze the data. Results: The results showed a greater post-intervention adjusted mean for body weight and LBM in the normal dietary group in comparison with the experimental group. After controlling for baseline measurements, there was a statistically significant difference in body weight (p < .0005) and BFM (p =.001) between groups. Conclusion: Resistance training along with a ketogenic diet may decrease BFM without notable changes in LBM, whilst RT on a normal diet might increase LBM without remarkably influencing BFM.