Secular Trends Beyond Stature: Sex-Specific Changes in Body Dimensions and Proportions Among South Korean Adults Aged 20–49 Years, 1986–2021

Abstract

Objectives

Whether adult body proportions keep changing once stature gains slow, and how this differs by sex, is unresolved. This study quantified 35-year change in 28 dimensions and 14 proportion indices of South Korean adults.

Methods

Seven national anthropometric surveys (Size Korea, 1986–2021; 24 979 adults aged 20–49) were harmonized on official measurement codes. Survey-wave rates were estimated with allometric adjustment for stature, a three-part sensitivity analysis for the 2003–2004 protocol change, paired sex contrasts, and age-adjusted cohort means.

Results

Stature rose 75 mm in men and 63 mm in women, while the sitting height ratio moved less than 0.1 points per decade. Transverse change was concentrated at the hip: sitting hip breadth rose 14% in men and 12% in women, biacromial breadth showed no detectable change, and the female hip–shoulder breadth index rose 1.59 points per decade. Girth change was mass-led in men (body weight+21%; BMI 22.8 to 25.1 kg/m²) and shape-led in women, whose waist circumference, waist-to-height ratio and waist-to-hip ratio rose at flat BMI. The male cephalic index fell 0.55 points per decade. Girth and hip results held at fixed stature; sitting hip breadth in both sexes and the male waist, hip, thigh and calf girths also held after protocol adjustment. Cohort stature was flat after the 1980–1984 birth cohort.

Conclusions

Secular change left segment proportions little altered, concentrated transverse change at the hip, and separated the sexes in the girths: mass-led in men, shape-led in women. Stature and BMI alone do not register it.