Underweight in young Japanese women over time: a longitudinal retrospective study of the change in body mass index from ages 6 to 20 years

Figures & data

Figure 1. Classification of the subjects.

Table 1. Medians and ranges of BMI, height, and weight of the subjects.

Age (years)	n	BMI (kg/m^2)	Height (cm)	Weight (kg)
		median (range)	median (range)	median (range)
6	601	15.0 (12.0–21.8)	117.0 (102.6–134.2)	20.6 (14.2–35.9)
7	598	15.0 (12.3–24.1)	123.0 (106.9–143.4)	22.7 (15.6–39.6)
8	598	15.3 (12.0–24.0)	128.9 (111.8–154.0)	25.4 (17.0–49.7)
9	596	15.6 (12.4–21.7)	134.4 (115.2–159.8)	28.2 (19.2–50.6)
10	594	15.9 (12.9–23.1)	141.0 (121.8–162.8)	31.9 (21.2–52.4)
11	598	16.7 (12.5–23.9)	148.0 (126.2–164.9)	36.8 (24.3–55.3)
12	599	17.7 (13.5–25.1)	152.9 (133.0–169.3)	41.9 (27.2–65.8)
13	601	18.5 (14.2–25.5)	156.1 (140.4–174.5)	45.3 (31.7–68.9)
14	601	19.2 (14.9–24.6)	157.8 (143.9–177.4)	47.8 (32.7–69.3)
15	598	19.5 (13.7–26.1)	158.6 (144.6–178.3)	49.1 (33.2–74.3)
16	598	20.0 (14.1–25.8)	159.0 (145.0–178.7)	50.4 (34.8–70.3)
17	590	20.1 (14.5–26.3)	159.3 (145.0–179.3)	50.9 (34.6–68.6)
18	582	19.9 (14.1–26.5)	159.4 (145.0–179.3)	50.4 (35.4–75.4)
19	563	20.1 (14.0–26.8)	159.3 (144.8–179.2)	50.8 (35.3–76.2)
20	601	20.0 (14.4–25.0)	159.5 (144.5–178.9)	50.9 (35.2–71.7)

BMI: body mass index.

Figure 2. Tracking BMI, height, and weight SDS. Open circles and dashed lines represent the healthy weight group. The solid circles and solid lines indicate the underweight group. The error bars represent 95% confidential intervals. (A) BMI SDS, (B) Height SDS, and (C) Weight SDS. BMI: body mass index; SDS: standard deviation score.

Figure 3. Tracking differences in BMI SDS (ΔBMI SDS) from 6 years of age. Open circles and dashed lines represent the healthy weight group. The solid circles and solid lines indicate the underweight group. The error bars represent 95% confidential intervals. BMI: body mass index; SDS: standard deviation score; ΔBMI SDS_6–N: differences in body mass index standard deviation score from the age of 6 years to “N” years.

Figure 4. Tracking BMI SDS in subgroups. (A) Comparison between the underweight₆–underweight₂₀ and underweight₆–healthy weight₂₀ groups. Solid squares and solid lines indicate the underweight₆–underweight₂₀ group. Solid squares and dashed lines indicate the underweight₆–healthy weight₂₀ group. The error bars represent 95% confidential intervals. (B) Comparison between the healthy weight₆–underweight₂₀ and healthy weight₆–healthy weight₂₀ groups. Open squares and solid lines show the healthy weight₆–underweight₂₀ group. Open squares and dashed lines show the healthy weight₆–healthy weight₂₀ group. The error bars represent 95% confidential intervals. BMI: body mass index; SDS: standard deviation score.

Figure 5. Tracking differences in BMI SDS (ΔBMI SDS) from 6 years of age in subgroups. (A) Comparison between the underweight₆–underweight₂₀ and underweight₆–healthy weight₂₀ groups. Solid squares and solid lines indicate the underweight₆–underweight₂₀ group. Solid squares and dashed lines indicate the underweight₆–healthy weight₂₀ group. The error bars represent 95% confidential intervals. (B) Comparison between the healthy weight₆–underweight₂₀ and healthy weight₆–healthy weight₂₀ groups. Open squares and solid lines show the healthy weight₆–underweight₂₀ group. Open squares and dashed lines show the healthy weight₆–healthy weight₂₀ group. The error bars represent 95% confidential intervals. BMI: body mass index; SDS: standard deviation score; ΔBMI SDS_6–N: differences in body mass index standard deviation score from the age of 6 years to “N” years.

Data availability statement

The participants of this study did not provide written consent for their data to be shared publicly; therefore, due to the sensitive nature of the research, supporting data is not available.