Health chiefs are targeting a city's schools after a 10-year-old pupil was found to weigh almost 20 stone.
The Year 6 child – whose identity or gender has not been revealed – is believed to be one of the heaviest children in Britain.
Three other primary school children were also found to be over 16 stone in the past three years in Coventry and Warwickshire.
One weighed 18st 6lbs, one was just over 18st, and another 16st 7lbs, as well as the heaviest child who weighed 19st 7lbs.
The children were weighed as part of the National Child Measurement Programme, a yearly weigh-in of reception and Year 6 children, the last year at primary school.
Coventry City Council said it has about 10,000 primary school children who are either overweight or clinically obese.
Berni Lee, the city's public health consultant, said the city was working with schools and midwives on healthy living and active lifestyle schemes. They are also targeting deprived areas where weight-related issues are highest.
She believes the programme is the best tool to measure the health of the nation's children.
She said: "Sometimes it can be wrong, especially if a child is borderline. It's not perfect.
"But the question is how do we work with parents, support them to make the changes that need to happen."
She added: "We've become accustomed to the overweight because it's so common in our society.
"But we shouldn't focus on weight, we should focus on the behaviours, their eating and the activity. "If we did this healthy weights will naturally follow."