Nonfocused low-intensity ultrasound is generally believed to be less efficacious than High-Intensity Focused Ultrasound (HIFU) at body fat reduction; nevertheless, this technology has already been widely used clinically for body contouring purposes. This study aimed to evaluate the efficacy and safety of this new technology by applying 1 MHz nonfocused ultrasound at 3 W/cm2 to the outer-thigh region of rat models. Ultrasonography measurement demonstrated an average reduction of 0.5 mm of subcutaneous fat thickness that persisted for at least three days after treatment. Biochemical analysis quantified a significant increase in lipid levels, specifically triglyceride, high-density lipoprotein, and total cholesterol. These two findings of subcutaneous fat reduction and plasma lipid increase showed a positive correlation. No evidence of adverse events or complications was observed after the treatment. This study validated nonfocused low-intensity ultrasound as an effective and safe method for body fat reduction, especially with repetitive treatment. However, the concurrent increase in plasma lipid level will require further investigation to determine this technology's long-term impact, if any, on health.