This study aims to investigate the effect of initial muscular fitness (MF) on weight loss and metabolically healthy status in 282 obese children under diet- and exercise-based interventions. Metabolically healthy obese (MHO) definitions established in 2018 and MF standards based on the 2021 Chinese children grip strength grading were applied. The proportion of metabolically unhealthy obese (MUO) was higher in the high MF group than their low MF counterparts at baseline. After intervention, neither group transitioned from MUO to MHO due to high frequency of low HDL-C. High MF females showed a higher percentage of high SBP than low MF females before and after intervention. High MF males exhibited greater improvements in waist circumference, hip circumference, waist-hip ratio, triglycerides, total cholesterol, and LDL-C than low MF males. The benefits of weight loss and blood lipid obtained by males are more evident than females under the same MF level. Thus, attention should be given to females during weight loss regardless of MF levels. We concluded that initial MF is not a primary factor influencing the transition from MUO to MHO status. Precision therapy should prioritize the management of blood pressure and avoid excessive reduction of HDL-C levels to sustain metabolic health.