Japan, once taller on average than both South Korea and China, has fallen behind its two neighbors. Japanese heights have been effectively flat since the 1990s, while average heights in Korea and China have risen steadily, widening the gap.
Among 19-year-olds, Japanese men are about 3 centimeters shorter than their Korean and Chinese counterparts, and Japanese women about 5 centimeters shorter.
Japan's Nihon Keizai Shimbun recently examined why the rise in Japanese heights came to a halt, drawing on data from the international research consortium NCD-RisC and analysis from experts.
Once Taller Than Korea and China, Japan Now Trails by Up to 5 Centimeters
According to NCD-RisC research published in the medical journal The Lancet in 2020, the average height of 19-year-old Japanese men was 172.1 centimeters in 2019, and 158.5 centimeters for women.
For the same age group, Korean men averaged 175.5 centimeters and women 163.2 centimeters, while Chinese men averaged 175.7 centimeters and women 163.5 centimeters.
That puts Korean men 3.4 centimeters taller than Japanese men and Korean women 4.7 centimeters taller. Chinese men were 3.6 centimeters taller and Chinese women 5 centimeters taller than their Japanese counterparts.
It was not always this way. Japanese heights climbed steadily after World War II on the back of economic growth and rising living standards, and for a time Japanese people were taller on average than Koreans or Chinese.
That growth began to slow in the 1990s. Average heights among 5- to 19-year-olds in Korea and China, by contrast, rose over the following 35 years at among the fastest rates in the world.
The result: Korea and China caught up and overtook Japan while Japanese growth stalled.
Flat for Three Decades in Japan, Rapid Gains in Korea and China
Japan's own statistics show the same stagnation. The average height of 17-year-old Japanese boys was recently measured at about 170.8 centimeters, essentially unchanged from the previous peak of 170.9 centimeters.
Analysts say the widening gap reflects continued gains in Korea and China during Japan's flat period rather than any significant decline in Japanese heights.
Growth conditions and nutrition during adolescence are cited in particular as factors behind the differences between countries.
Daily Intake Around 1,900 Calories: Nutrition, Low Birth Weight and Sleep
Experts point to a range of factors behind the plateau, including nutritional intake, conditions at birth and hours of sleep.
Average daily energy intake in Japan fell over a long period and has recently held at about 1,900 calories, lower than in Korea or China.
Failing to take in enough calories, protein and other nutrients during the growth years can affect final adult height, according to the analysis.
Birth weight is also cited as a possible factor. Japan has a relatively high share of low-birth-weight babies, defined as those weighing less than 2.5 kilograms at birth.
Sleep duration and lifestyle habits during the growth years may also be linked to the plateau in average height.
Because genetic factors themselves have not changed significantly, experts see shifts in nutrition and growth conditions driven by economic and social change as the main reason Japanese heights are no longer rising much.
