The beta3 adrenergic receptor (ADRB3) is a part of the adrenergic system, which is known to play a key role in energy metabolism. The relationship between the Trp64Arg variant of ADRB3 and body mass index (BMI) has been widely examined; however, the results of these studies have been inconsistent. Therefore, we performed a meta-analysis of the relationship between an ADRB3 variant and BMI in 2008. Our results suggested that the Trp64Arg variant of ADRB3 was associated with BMI in East Asians, but not Europeans. Additionally, our report showed the importance of meta-analyses in the field of genetic association studies for common traits. In 1995, Yoshida et al. reported that the Trp64Arg variant of ADRB3 was related to difficulty in weight loss. The decrease in body weight in obese subjects with the mutation was lower than that in obese subjects without the mutation following a 3 month combined low-calorie diet and exercise regimen. However, subsequent studies have yielded inconsistent results. Accordingly, further studies are needed to reliably assess and interpret gene-phenotype associations with this ADRB3 variant.