Body mass index combined with (waist + hip)/height accurately screened for normal-weight obesity in Chinese young adults

•Predictors of body fat percentage with age and sex for each ethnic group are needed.•Normal-weight obesity is based on body composition plus anthropometric measurements.•Downregulating the upper body mass index is based on (waist + hip)-to-height ratio for easy normal-weight obesity assessment. Only a few studies have explored the prevalence of normal-weight obesity in young adults or the development of a simple evaluation index for body fat percentage. Therefore, this study aimed to examine the prevalence of normal-weight obesity in young Chinese adults and use anthropometric measurements to develop an evaluation index. In total, 1322 college students participated in the study and were divided into the normal-weight lean, normal-weight obese, and overweight and obese groups based on their body mass index and body fat percentage. The differences in body composition, circumference, and circumference ratio among these three groups were examined. When exploring the correlation between the circumference ratio and body fat percentage, the circumference ratio was suitable for early screening of abnormal body fat percentage, and the cutoff value was calculated. Body composition and circumference were significantly different among the three groups: (waist + hip)-to-height, hip-to-height, and waist-to-height ratios were strongly correlated with body fat percentage. (Waist + hip)-to-height ratio can be used as a simple evaluation index for indicating abnormal body fat percentage when higher than 1.032 in male and 1.047 in female individuals. Downregulating the normal upper limit for body mass index to 24.4 and 23.8 kg/m2 in male and female individuals, respectively, is recommended. Body mass index combined with (waist + hip)-to-height ratio allowed for more accurate screening of normal-weight obesity as an easy and cost-free evaluation measure for abnormal body fat percentage.