British researchers studying childhood obesity say the so-called puppy fat doesn’t go away in teenage years as widely believed, but mostly stays.

The experts at the University College London say children who are overweight or obese at 11 years old remain so through adolescence and probably into adulthood, reports the Independent newspaper. The findings, based on a study of about 6,000 children from age 11 to 16, appear in the British Medical Journal.

The study said obesity is established earlier than previously thought and dismissing it as puppy fat can have serious health implications in later years.

More than a quarter of children in Britain are now reported to be overweight or obese. Doctors say they already see early signs of heart disease, diabetes and liver damage in children as young as 10 because of their weight.