“Let the child eat. It all turns into height in the end.” Korean parents hear this constantly, and there was a time when it was sound. Nutrition was short, and a child putting on weight really did have more to build with. Two things have changed since then, and together they change the answer. This article covers childhood growth and why the old saying no longer transfers.
In Summary
- The saying made sense in an era of scarce nutrition. It does not transfer well to children today.
- Activity has collapsed. Children once spent the day outdoors, and what they ate was spent on growing. School, academies and homework now fill the day sitting down, and rest time often goes to screens.
- Food has changed. High-calorie, high-fat processed food is easy to reach and tends to be stored rather than used for growth.
- Intake up, output down — and the surplus is more likely to become body fat than height.
- Increased body fat can stimulate sex hormone secretion, which can bring secondary sexual characteristics earlier.
- Earlier menarche means growth plates close earlier, so the child may stop short of the height they could have reached.
- Genetics matters most for height. But reaching the predicted range — or exceeding average despite shorter parents — is meaningfully influenced by environment.
- Five things help: managing chronic illness, sufficient sleep, balanced eating, appropriate exercise, and waiting.
What Changed
Activity
Children used to run around outside all day. Whatever they ate was consumed as the energy that growing requires.
Now most of the day is spent seated — school, then academies, then homework. And the time that is left over frequently goes to watching video or gaming, which are also sedentary. The absolute quantity of energy spent has fallen a long way.
Food
High-calorie, high-fat processed food is far easier to come by than it was. It tends to produce nutritional imbalance, and what it supplies is more readily stored as body fat than directed into growth.
Put the two together — intake rising while activity falls — and the surplus has to go somewhere. Increasingly it goes to childhood obesity rather than height.
Why This Matters for Final Height
Childhood obesity is not only a matter of weight. It can bear directly on how tall a child finishes.
Increased body fat can stimulate the secretion of sex hormones, which can bring secondary sexual characteristics on earlier than in peers. Where menarche arrives early, the growth plates close that much sooner — and growth can stop before the child has reached the height they were capable of.
I want to be careful about how this lands. This is a reason to attend to a child’s activity and diet as a matter of health; it is not a reason to put a child on a diet, or to make weight a subject of anxiety in the household. Concern about a child’s growth or weight belongs with their paediatrician, who can assess whether anything is actually off track.
Five Things That Help
Height is largely genetic — that much is true. But whether a child grows to the range their genetics predict, or exceeds the average despite shorter parents, is meaningfully open to environment. Five conditions matter.
1. Manage chronic illness
Chronic inflammatory conditions such as allergic rhinitis or atopic dermatitis interfere with sound sleep and consume energy that would otherwise go to growth. Treating and managing these comes first, before anything else on this list.
2. Sufficient sleep
Growth hormone is secreted vigorously during deep sleep. Regular sleep habits that let a child sleep soundly are not a supporting measure here — they are close to the centre of it.
3. Balanced eating
Eating a great deal matters less than eating across the range — protein, calcium, vitamins, the nutrients growth actually requires. Processed food is the thing to reduce.
4. Appropriate exercise
Exercise that stimulates the growth plates — skipping rope, basketball — helps. Which in practice means adjusting excessive study hours to secure time for a child to run around. That is a scheduling decision more than a medical one, and it is usually the hardest of the five.
5. Waiting
If the four conditions above are in place, the remaining task is to wait.
Plenty of children simply grow late. I grew another two or three centimetres myself after starting university. A child who is behind their peers at twelve is not thereby finished growing, and treating them as though they were does no good.
When the Four Are Hard to Keep
Parents generally know these rules in theory. What makes them hard in practice is the child — poor appetite, frequent fatigue, trouble sleeping.
Where household effort alone is not enough to shift those, a KTM assessment can look at what is getting in the way. Korean Traditional Medicine (KTM), the traditional healing system of Korea also known as Hanbang (한방), approaches this by identifying the child’s constitution and state of health and addressing what is impeding growth — poor appetite and disturbed sleep among the usual candidates.
Whether that is appropriate for a particular child is a matter for consultation, alongside their paediatric care rather than instead of it. A child who is genuinely off their growth curve needs paediatric assessment first.
Summary
The saying was never wrong so much as time-limited. It described a world where children were short of food and long on movement, and we now have the opposite arrangement.
Which means the useful question is not whether a child is eating enough, but whether what they eat is being spent.
Related: Why Korea Has Postpartum Wind and the West Does Not
