What is childhood obesity?

How is childhood obesity defined?

In Sweden, childhood obesity is diagnosed using iso-BMI, an age- and sex-adjusted BMI measure according to Cole 2000:

• Iso-BMI 30–34.9 = class 1 obesity
• Iso-BMI 35–39.9 = class 2 obesity
• Iso-BMI 40+ = class 3 obesity

Overweight (iso-BMI 25–30) is something else — it is not classified as a disease. Obesity, on the other hand, is a chronic disease that should be treated within healthcare. See the difference between overweight and obesity in children.

How common is childhood obesity in Sweden?

Approximately 6–7% of Swedish school-age children have obesity, and a further ~20% have overweight. The prevalence has increased over recent decades. More detail in how many children in Sweden have obesity.

What causes childhood obesity?

Childhood obesity is rarely due to a single cause. It is an interplay between:

• Genetics and biology — heritability is high, around 50–70%. See is obesity hereditary.
• Hormonal factors — the brain's regulation of hunger and satiety.
• Environment — availability of energy-dense food, marketing, meal patterns.
• Sleep — too little sleep independently increases the risk.
• Sedentary behaviour — particularly screen time during leisure hours.
• Stress and mental health difficulties — can both cause and exacerbate obesity.

More in-depth reading in what causes obesity.

How is childhood obesity treated?

Treatment is family-based and takes place over an extended period:

1. Structured family treatment — support with meal routines, sleep, screen time, and physical activity. Often lasts 1–2 years. See how long does treatment take.
2. Regular monitoring — iso-BMI, well-being, and any complications.
3. Medication — in severe obesity in adolescents, GLP-1 analogues may be considered; see Ozempic for children.
4. Bariatric surgery — in very severe obesity in older adolescents, following careful assessment.

Many Swedish paediatric and adolescent clinics use digital treatment support from Evira. On evira.se, you can see which clinics are connected.

Complications to be aware of

Obesity in childhood increases the risk of:

• Type 2 diabetes and insulin resistance
• High blood pressure
• Fatty liver disease (NAFLD)
• Sleep apnoea
• Joint problems
• Mental health difficulties, often secondary to stigmatisation

Early treatment reduces these risks considerably.

Where should you turn?

• BVC (child health centre) or school health services — for an initial assessment and referral.
• The primary care centre (vårdcentral) — if the child is no longer under BVC or school health services.
• BUMM or a paediatric outpatient clinic — for assessment and treatment; see investigation at BUMM.
• Specialist obesity units — in cases of severe obesity or complications.

A word on language

Never tell a child that they are "fat", "chubby", or "need to lose weight". Comments about weight and appearance from parents increase the risk of eating disorders and low self-esteem — without helping weight. See how to talk to children about overweight.

Related questions

• What is childhood obesity?Childhood obesity is an iso-BMI of 30 or higher — a chronic disease that should be treated within healthcare.
• Is obesity hereditary?The heritability of BMI is 40–70%. But genes do not decide alone — here is how the family can influence the risk.
• What causes obesity?Obesity is caused by an interplay between genetics, hormones, environment and habits — not willpower.

See all questions and answers →