A Child Who Eats Sweet Things Often Says Their Head Hurts

"She loves sweet things, and she often says her head hurts."

I hear this from parents often enough. When I do, I ask less about what was eaten than about when the pain comes.

A steep rise brings a steep fall

The body reads not only how high blood sugar is but how fast it is rising. A steep rise draws a steep answer. (The Body Does Not Hold an Exact Number)

But stopping exactly is hard. So it can end up lower than where it started.

In a study of adolescents given a high-glycaemic-index meal, insulin rose, blood sugar then fell below its starting point, and adrenaline rose with it. The body had set out to bring the lowered sugar back.

Why the body answers so fast

There is a reason the body is so quick about blood sugar falling.

The brain runs almost solely on glucose. And it has nowhere to store it. Unlike muscle or liver it keeps no reserve and must take it from the blood continuously.

So the body treats the falling side far more urgently than the rising one. Somewhat high it will handle over time; falling, it sends several signals at once. That is why adrenaline goes first.

And this is what the child looks like

When the signals that raise blood sugar go out, the body is not quiet. The heart runs, hands tremble, cold sweat comes, irritability rises, concentration goes.

A child cannot put this into words. So it comes out as "my head hurts," "I've no energy," "leave me alone." To a parent it looks like the child going odd some while after eating.

Though I do not call it a hypoglycaemic headache

Here I have to speak carefully.

Headache is indeed on the list of symptoms of low blood sugar. But that a headache from going without food is therefore caused by low blood sugar is not settled. The international classification of headache does not assert that link.

So I do not explain it by blood sugar alone. I read it this way instead — a child whose swings are wide has several symptoms together. Headache is one of the forms it takes; in another child it comes out in sleep, or mood, or the stomach.

It shows more plainly in children

The same thing happens in adults, but it shows larger in a child.

A child has less to store and uses more. The brain is large for the body and takes more glucose than an adult's, while the reserve laid down in the liver is smaller. It is the same reason they last a shorter time without eating. (A Child's Body Is Not a Scaled-Down Adult's)

With little in reserve, the same swing moves them more. A width an adult would have passed over comes out as symptoms in a child.

So what I ask

• When it happens — an hour or two after eating, or after a missed meal
• After what — something quickly absorbed, like a drink or a biscuit
• What comes with it — irritability, trembling hands, trouble sleeping

The timing is the clue. The same headache calls for looking at different places depending on when it comes.

What I work on is not the total

I do not say the answer is cutting sweet things out altogether. With a child that is not kept to anyway.

What I look at is the speed of the rise. The same food gives a different curve on an empty stomach or alongside other things, eaten fast or slowly. Ease the width and the response that follows grows smaller too.

It is not a story about eating less but about the order and the speed of eating.

When to see a doctor first

If the headaches are worsening, if they are worst on waking, if vomiting comes with them, or if walking or vision has changed — before a story like this, examination and testing come first.

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Sources

• Hypoglycaemia — symptoms and what to do — Asan Medical Center
• A study measuring that in human islets the first insulin release varies with the speed at which glucose rises — American Journal of Physiology – Endocrinology and Metabolism, 2025

Written by Dr. Heo Ji-young (Ph.D. in Korean Medicine Pathology, Kyung Hee University · former Research Professor of Herbology, Kyung Hee University)