Here, we evaluated the effects of NR on the thermogenic response, highlighting the brown adipose tissue (BAT) in lean mice...The experimental approaches demonstrated that oral NR supplementation reduced the abdominal visceral fat depots, with discrete impact on oxygen consumption in C57BL/6J mice. Interestingly, NR significantly increased the body temperature, and this phenomenon was accompanied by high levels of UCP1 protein content and Pgc1α mRNA in BAT. This study demonstrated the oral NR supplementation was sufficient to induce the thermogenic response in lean mice changing the BAT metabolism.