The prevalence of central obesity in the total population has been reported in numerous studies. However, information on the prevalence of central obesity within normal-category BMI is scant. In the present study, we examined the profiles of central obesity among normal-weight children and adolescents. A total of 29 516 (14 226 boys and 15 290 girls) normal-weight children and adolescents (excluding underweight, overweight and obesity) aged 7–18 years were included in the final analysis. Central obesity was defined by the international age- and sex-specific cut-offs of waist circumference (WC) and threshold of waist:height ratio (WHtR ≥ 0·5). All subjects were classified into four groups (Q1–Q4) according to the age- and sex-specific quartiles of BMI, those in the upper fourth (Q4) were defined as ‘high-normal BMI’ and those in the lower fourth (Q1) were defined as ‘low-normal BMI’. The prevalence of central obesity as measured by WC was 9·90 (95 % CI 9·41, 10·39) % for boys and 8·11 (95 % CI 7·68, 8·54) % for girls; by WHtR was 2·97 (95 % CI 2·69, 3·25) % for boys and 2·44 (95 % CI 2·20, 2·68) % for girls. Subjects in the Q4 group had a much higher prevalence of central obesity than their counterparts in the Q1 group (P < 0·01). Our findings suggest that the health risks of children with normal-weight central obesity may be missed when BMI is used alone as a measure; it is meaningful to include WC in clinical practice and to include the simple message ‘Keep your waist to less than half your height’.

中文翻译：

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山东省正常体重儿童青少年中心性肥胖筛查

许多研究报告了总人口中中心性肥胖的患病率。然而，关于正常类 BMI 中中心性肥胖患病率的信息很少。在本研究中，我们检查了正常体重儿童和青少年的中心性肥胖特征。最终分析共纳入 29 516 名（14 226 名男孩和 15 290 名女孩）年龄在 7-18 岁的正常体重儿童和青少年（不包括体重不足、超重和肥胖）。中心性肥胖由国际年龄和性别的腰围（WC）和腰围阈值：身高比阈值（WHtR ≥ 0·5）定义。根据BMI的年龄和性别特定四分位数将所有受试者分为四组（Q1-Q4），上四分（Q4）被定义为“高正常BMI”，下四分（Q1）被定义为“低正常BMI”。以 WC 测得的中心性肥胖患病率男孩为 9·90 (95 % CI 9·41, 10·39) %，女孩为 8·11 (95 % CI 7·68, 8·54) %；WHtR 为男孩的 2·97 (95 % CI 2·69, 3·25) % 和女孩的 2·44 (95 % CI 2·20, 2·68) %。Q4 组受试者的中心性肥胖患病率远高于 Q1 组受试者（磷< 0·01)。我们的研究结果表明，当单独使用 BMI 作为衡量标准时，可能会忽略正常体重中心性肥胖儿童的健康风险；将 WC 纳入临床实践并包含简单的信息“保持腰部低于身高的一半”是有意义的。