Short answer
Yes, children with obesity have an increased risk of fatty liver disease (metabolic-associated steatotic liver disease, MASLD). Studies show that up to 30 percent of children with obesity have fat accumulation in the liver. It rarely causes symptoms — it is detected via elevated liver function tests. The treatment is weight reduction, which in most cases causes the liver changes to regress.
What fatty liver is
Fatty liver means that fat accumulates in the liver cells. In adults, it is often linked to alcohol — in children, it is almost always MASLD (metabolic-associated steatotic liver disease, previously called NAFLD). It is a complication of insulin resistance and overweight/obesity, not something caused by anything the child has done wrong.
In the early stages, it is simply fat accumulation. If allowed to continue for years, it can develop into inflammation (MASH), scarring, and in the worst case cirrhosis — but that is uncommon during childhood.
How common is it?
- In children of normal weight: below 5 percent.
- In children with overweight: approx. 15–20 percent.
- In children with obesity: approx. 25–35 percent.
- In children with severe obesity: up to 40 percent.
The risk is higher in boys and increases with age. Teenage boys with obesity represent the largest risk group.
Symptoms
This is the trickiest part — fatty liver usually causes no symptoms at all in children. That is why it goes unnoticed. Occasionally, the child may have:
- Tiredness or a feeling of heaviness.
- Vague discomfort under the right rib cage.
- Darker skin on the neck or in the armpits (acanthosis nigricans — a sign of insulin resistance).
However, the vast majority of children with fatty liver feel subjectively well. That is why blood tests are included in an assessment for childhood obesity.
How it is detected
At BUMM (paediatric outpatient clinic), liver function tests (ALT in particular) are taken as part of the routine investigation for obesity. If ALT is elevated, further investigation is carried out — usually an ultrasound of the liver. If more advanced disease is suspected, the child may be referred to a paediatric gastroenterologist.
Treatment
There is no approved medication for fatty liver in children. The treatment is weight reduction — and it works. Studies show that a 5–10 percent weight reduction often normalises liver function tests and reduces fat accumulation. This means that the same treatment given for obesity (family-based lifestyle habits, sometimes medications such as GLP-1 analogues, and as a last resort bariatric surgery for teenagers) also treats the fatty liver.
When you should request a liver function test
If your child has an iso-BMI above 30 and liver function tests were not taken during the most recent assessment — ask for them. It is a simple blood test that can detect something that would otherwise remain invisible for years.
Related questions
- When is overweight in children something to take seriously?The patterns that signal overweight needs investigation — and where to seek help.
- What happens during a BUMM assessment for childhood obesity?Step by step through the first BUMM visit — what is measured, which tests are taken, and how to prepare your child.
- How long does treatment for childhood obesity take?Treatment for childhood obesity is a multi-year effort — here is what the timeline looks like, from the first BUMM visit to the maintenance phase.
Sources
- Nationellt vårdprogram för behandling av obesitas hos barn och ungdomar (2023)
- Internetmedicin — Fettlever hos barn (MASLD/NAFLD)
- ESPGHAN — Diagnosis of fatty liver disease in children (2017)
- Anderson et al. (2015) — Prevalence of non-alcoholic fatty liver disease in children, PLOS ONE
Last updated: April 2026