An optimal BMI cutoff is needed in public health and clinical settings as the guidance an optimal body weight. Although body mass index (BMI) cutoffs of 25 and 30 kg/m2 for overweight and obesity, respectively, have been widely used among Westerners and recommended by the World Health Organization as an international criterion for body fatness at the population level, there are still controversial opinions about the optimal BMI cutoffs for Asians. We conducted the study to determine an optimal BMI cutoff for overweight, which represents elevated hypertension and to determine the best anthropometric index in the prediction of hypertension in Asians. We used data from representative surveys conducted in China, Indonesia, and Vietnam in the early 2000s. With the use of ROC curve analyses, both longitudinal and cross-sectional studies suggest an optimal BMI cutoff of < 25 kg/m2. The lower optimal BMI level is beneficial for Asians because it triggers earlier preventions for overweight and non-communicable diseases (NCDs), and thus, reduces economic and health burdens due to overweight and NCDs among Asians worldwide. In addition, our study shows ethnic differences in optimal BMI cutoffs between Chinese, Indonesian, and Vietnamese adults and suggests the use of country specific BMI cutoffs. We contribute to current knowledge by providing a BMI cutoff based on a longitudinal sample in Asians and a sample of Southeast Asians. With the use of the change-in-estimate approach, our findings show that waist circumference does not perform better than BMI or adds meaningfully to the prediction of hypertension outcome by BMI. BMI appears to be sufficient to screen for cardiovascular risk in Asians.