Table 1. Crude and weighted characteristics of Korean adults based on data obtained from the KNHANES from 1998 to 2021 (n=135,671)

Total 1998–2005 2007–2009 2010–2012 2013–2015 2016–2019 2020 2021
Overall, n (%) 135,671 62,163 14,598 15,610 13,440 20,601 4,613 4,646
Crude rate, n (%)
Age (years), n (%)
30–39 32,839 (24.20) 18,637 (13.74) 3,425 (2.52) 3,280 (2.42) 2,489 (1.83) 3,653 (2.69) 732 (0.54) 623 (0.46)
40–49 32,387 (23.87) 17,034 (12.56) 3,328 (2.45) 3,139 (2.31) 2,768 (2.04) 4,294 (3.17) 914 (0.67) 910 (0.67)
50–59 26,991 (19.89) 11,341 (8.36) 2,817 (2.08) 3,382 (2.49) 3,016 (2.22) 4,458 (3.29) 1,011 (0.75) 966 (0.71)
≥60 43,454 (32.03) 15,151 (11.17) 5,028 (3.71) 5,809 (4.28) 5,167 (3.81) 8,196 (6.04) 1,956 (1.44) 2,147 (1.58)
Sex, n (%)
Male 60,834 (44.84) 29,422 (21.69) 6,174 (4.55) 6,648 (4.90) 5,633 (4.15) 8,892 (6.55) 2,041 (1.50) 2,024 (1.49)
Female 74,837 (55.16) 32,741 (24.13) 8,424 (6.21) 8,962 (6.61) 7,807 (5.75) 11,709 (8.63) 2,572 (1.90) 2,622 (1.93)
Region of residence, n (%)
Urban 101,925 (75.13) 44,906 (33.10) 10,449 (7.70) 12,147 (8.95) 10,718 (7.90) 16,524 (12.18) 3,640 (2.68) 3,541 (2.61)
Rural 33,746 (24.87) 17,257 (12.72) 4,149 (3.06) 3,463 (2.55) 2,722 (2.01) 4,077 (3.01) 973 (0.72) 1,105 (0.81)
BMI group, n (%)
Underweight 3,048 (2.25) 610 (0.45) 525 (0.39) 535 (0.39) 443 (0.33) 639 (0.47) 132 (0.10) 164 (0.12)
Normal weight 33,856 (24.95) 6,436 (4.74) 5,518 (4.07) 6,040 (4.45) 5,097 (3.76) 7,621 (5.62) 1,560 (1.15) 1,584 (1.17)
Overweight 21,881 (16.13) 4,103 (3.02) 3,616 (2.67) 3,794 (2.80) 3,312 (2.44) 4,894 (3.61) 1,075 (0.79) 1,087 (0.80)
Obese 30,692 (22.62) 5,191 (3.83) 4,854 (3.58) 5,181 (3.82) 4,576 (3.37) 7,370 (5.43) 1,784 (1.31) 1,736 (1.28)
Unknown 46,194 (34.05) 45,823 (33.78) 85 (0.06) 60 (0.04) 12 (0.01) 77 (0.06) 62 (0.05) 75 (0.06)
Education, n (%)
Elementary school or lower education 36,268 (26.73) 18,584 (13.70) 4,519 (3.33) 4,157 (3.06) 3,214 (2.37) 4,138 (3.05) 766 (0.56) 890 (0.66)
Middle school 18,437 (13.59) 9,216 (6.79) 1,953 (1.44) 2,020 (1.49) 1,727 (1.27) 2,436 (1.80) 551 (0.41) 534 (0.39)
High school 43,008 (31.70) 21,334 (15.72) 4,397 (3.24) 4,628 (3.41) 4,014 (2.96) 5,903 (4.35) 1,375 (1.01) 1,357 (1.00)
College or higher education 37,958 (27.98) 13,029 (9.60) 3,729 (2.75) 4,805 (3.54) 4,485 (3.31) 8,124 (5.99) 1,921 (1.42) 1,865 (1.37)
Smoking status, n (%)
Current smoker 18,860 (13.90) 5,987 (4.41) 3,094 (2.28) 3,116 (2.30) 1,686 (1.24) 3,533 (2.60) 744 (0.55) 700 (0.52)
Ex-smoker 18,640 (13.74) 2,440 (1.80) 2,973 (2.19) 3,331 (2.46) 2,811 (2.07) 4,777 (3.52) 1,140 (0.84) 1,168 (0.86)
Non-smoker 54,722 (40.33) 11,047 (8.14) 8,524 (6.28) 9,163 (6.75) 8,190 (6.04) 12,291 (9.06) 2,729 (2.01) 2,778 (2.05)
Unknown 43,449 (32.03) 42,689 (31.47) 7 (0.01) N/A 753 (0.56) N/A N/A N/A
Household income, n (%)
Lowest quartile 30,305 (22.34) 14,911 (10.99) 3,327 (2.45) 3,296 (2.43) 2,799 (2.06) 4,164 (3.07) 857 (0.63) 951 (0.70)
Second quartile 33,777 (24.90) 15,336 (11.30) 3,628 (2.67) 4,043 (2.98) 3,388 (2.50) 5,135 (3.78) 1,111 (0.82) 1,136 (0.84)
Third quartile 35,646 (26.27) 16,109 (11.87) 3,821 (2.82) 4,126 (3.04) 3,591 (2.65) 5,472 (4.03) 1,274 (0.94) 1,253 (0.92)
Highest quartile 35,943 (26.49) 15,807 (11.65) 3,822 (2.82) 4,145 (3.06) 3,662 (2.70) 5,830 (4.30) 1,371 (1.01) 1,306 (0.96)
Weighted rate (95% CI)
Age (years), weighted % (95% CI)
30–39 25.68 (25.19 to 26.18) 31.03 (30.18 to 31.87) 28.07 (26.59 to 29.54) 25.87 (24.57 to 27.18) 23.62 (22.29 to 24.94) 21.69 (20.56 to 22.83) 20.83 (18.47 to 23.20) 19.98 (17.91 to 22.05)
40–49 26.50 (26.09 to 26.92) 28.93 (28.25 to 29.61) 28.23 (27.02 to 29.44) 26.95 (25.73 to 28.16) 25.51 (24.41 to 26.62) 24.48 (23.54 to 25.43) 23.74 (21.67 to 25.81) 22.94 (20.94 to 24.94)
50–59 21.75 (21.37 to 22.12) 17.63 (17.11 to 18.15) 20.48 (19.52 to 21.44) 22.56 (21.52 to 23.60) 24.10 (23.03 to 25.17) 24.21 (23.34 to 25.08) 24.65 (22.68 to 26.63) 23.37 (21.34 to 25.40)
≥60 26.07 (25.63 to 26.51) 22.42 (21.77 to 23.07) 23.22 (22.13 to 24.31) 24.62 (23.52 to 25.73) 26.77 (25.58 to 27.95) 29.61 (28.41 to 30.81) 30.77 (28.08 to 33.47) 33.71 (31.13 to 36.30)
Sex, weighted % (95% CI)
Male 48.62 (48.36 to 48.88) 48.32 (48.03 to 48.62) 49.06 (48.34 to 49.79) 48.68 (47.96 to 49.40) 47.85 (47.08 to 48.63) 48.78 (48.16 to 49.41) 49.55 (48.36 to 50.73) 49.36 (47.94 to 50.78)
Female 51.38 (51.13 to 51.64) 51.68 (51.38 to 51.97) 50.94 (50.21 to 51.66) 51.32 (50.60 to 52.04) 52.15 (51.37 to 52.93) 51.22 (50.59 to 51.84) 50.45 (49.27 to 51.64) 50.64 (49.22 to 52.06)
Region of residence, weighted % (95% CI)
Urban 80.91 (79.87 to 81.96) 79.52 (78.72 to 80.33) 79.05 (75.82 to 82.28) 78.34 (74.90 to 81.79) 81.49 (78.46 to 84.51) 83.83 (81.27 to 86.38) 84.07 (78.73 to 89.41) 82.65 (77.26 to 88.04)
Rural 19.09 (18.04 to 20.13) 20.48 (19.67 to 21.28) 20.95 (17.72 to 24.18) 21.66 (18.21 to 25.10) 18.51 (15.49 to 21.54) 16.17 (13.62 to 18.73) 15.93 (10.59 to 21.27) 17.35 (11.96 to 22.74)
BMI group, weighted % (95% CI)
Underweight 2.58 (2.46 to 2.70) 0.82 (0.70 to 0.94) 3.37 (3.04 to 3.71) 3.22 (2.86 to 3.58) 3.21 (2.86 to 3.55) 3.11 (2.83 to 3.39) 2.90 (2.24 to 3.57) 3.38 (2.75 to 4.01)
Normal weight 29.39 (28.98 to 29.80) 9.00 (8.17 to 9.82) 37.04 (36.09 to 37.99) 37.50 (36.48 to 38.51) 37.87 (36.91 to 38.84) 36.45 (35.62 to 37.27) 32.51 (30.82 to 34.20) 34.49 (32.74 to 36.24)
Overweight 19.42 (19.10 to 19.74) 6.17 (5.59 to 6.74) 25.00 (24.19 to 25.80) 24.28 (23.42 to 25.14) 24.47 (23.63 to 25.31) 23.81 (23.10 to 24.51) 23.87 (22.38 to 25.36) 22.07 (20.57 to 23.56)
Obese 28.40 (28.00 to 28.79) 8.06 (7.30 to 8.81) 34.02 (33.06 to 34.97) 34.55 (33.54 to 35.56) 34.37 (33.44 to 35.30) 36.29 (35.45 to 37.12) 39.54 (37.82 to 41.27) 38.76 (36.91 to 40.62)
Unknown 20.22 (19.58 to 20.85) 75.96 (73.85 to 78.07) 0.58 (0.40 to 0.75) 0.45 (0.30 to 0.61) 0.09 (0.02 to 0.15) 0.35 (0.25 to 0.46) 1.18 (0.83 to 1.52) 1.30 (0.91 to 1.68)
Education, weighted % (95% CI)
Elementary school or lower education 19.62 (19.21 to 20.03) 25.15 (24.36 to 25.95) 22.95 (21.79 to 24.11) 20.95 (19.83 to 22.07) 18.11 (17.02 to 19.20) 14.90 (14.02 to 15.79) 11.42 (9.62 to 13.22) 12.48 (10.60 to 14.37)
Middle school 11.83 (11.57 to 12.09) 13.74 (13.28 to 14.21) 12.97 (12.23 to 13.71) 12.43 (11.71 to 13.15) 11.24 (10.55 to 11.93) 10.18 (9.60 to 10.77) 9.33 (8.10 to 10.56) 8.94 (7.79 to 10.09)
High school 33.18 (32.75 to 33.62) 36.81 (36.07 to 37.56) 33.85 (32.63 to 35.08) 33.09 (31.90 to 34.29) 32.18 (31.00 to 33.36) 30.14 (29.16 to 31.11) 31.29 (29.13 to 33.44) 31.02 (29.00 to 33.04)
College or higher education 35.37 (34.75 to 35.98) 24.29 (23.36 to 25.21) 30.23 (28.65 to 31.81) 33.53 (31.99 to 35.06) 38.48 (36.90 to 40.05) 44.78 (43.21 to 46.35) 47.96 (44.36 to 51.56) 47.56 (44.31 to 50.80)
Smoking status, weighted % (95% CI)
Current smoker 17.84 (17.46 to 18.23) 8.98 (8.16 to 9.79) 25.63 (24.80 to 26.46) 25.71 (24.75 to 26.68) 15.37 (14.24 to 16.51) 20.33 (19.55 to 21.10) 18.71 (17.11 to 20.30) 17.29 (15.77 to 18.82)
Ex-smoker 18.07 (17.78 to 18.37) 4.52 (4.04 to 5.00) 21.49 (20.75 to 22.24) 21.31 (20.52 to 22.10) 21.32 (20.53 to 22.10) 23.98 (23.33 to 24.63) 25.95 (24.64 to 27.25) 26.99 (25.47 to 28.50)
Non-smoker 45.01 (44.49 to 45.53) 17.42 (15.89 to 18.95) 52.82 (51.98 to 53.67) 52.98 (52.11 to 53.85) 56.38 (55.53 to 57.24) 55.69 (54.93 to 56.46) 55.35 (53.77 to 56.93) 55.72 (53.81 to 57.63)
Unknown 19.07 (18.30 to 19.84) 69.08 (66.40 to 71.77) 0.05 (0.00 to 0.11) N/A 6.92 (5.93 to 7.91) N/A N/A N/A
Household income, weighted % (95% CI)
Lowest quartile 18.06 (17.61 to 18.50) 22.69 (21.80 to 23.59) 17.26 (16.08 to 18.43) 17.50 (16.37 to 18.62) 16.55 (15.37 to 17.72) 16.12 (15.12 to 17.11) 14.50 (12.21 to 16.79) 14.27 (12.31 to 16.22)
Second quartile 24.86 (24.41 to 25.32) 24.90 (24.14 to 25.66) 24.75 (23.50 to 26.00) 27.51 (26.18 to 28.84) 24.45 (23.21 to 25.69) 24.28 (23.26 to 25.29) 22.34 (20.16 to 24.53) 23.68 (21.51 to 25.84)
Third quartile 28.10 (27.64 to 28.55) 26.03 (25.31 to 26.75) 28.53 (27.27 to 29.79) 28.11 (26.94 to 29.29) 29.20 (27.83 to 30.58) 28.75 (27.74 to 29.77) 29.40 (27.13 to 31.67) 30.22 (28.08 to 32.35)
Highest quartile 28.98 (28.35 to 29.62) 26.38 (25.34 to 27.41) 29.46 (27.62 to 31.31) 26.88 (25.44 to 28.32) 29.80 (28.04 to 31.57) 30.86 (29.36 to 32.35) 33.76 (30.23 to 37.28) 31.84 (28.26 to 35.42)
Abbreviations: BMI, body mass index; CI, confidence interval; KNHANES, Korea National Health and Nutrition Examination Survey.
According to Asian-Pacific guidelines, BMI is divided into four groups: underweight (<18.5 kg/m2), normal (18.5-22.9 kg/m2), overweight (23.0–24.9 kg/m2), and obese (≥25 kg/m2).