The new guidance is intended for health professionals and those who provide specialist weight management services for children.
The guidance stresses it is "important it is to ensure the family and the child or young person recognise and accept that they are overweight or obese.
"Conversely, a lack of recognition or denial that the child or young person is overweight or obese can hinder uptake and adherence to a lifestyle weight management programme."
Many overweight and obese children and young people may have, or come from a family with, a "history of failed attempts to manage their weight", the guidance goes on.
A family's attitudes towards diet, exercise and the amount of time spent being sedentary should all be explored, it added.
More top news
A Public Health England report estimated 150,000 to 200,000 Britons are infected with the virus by imported pork every year.
Tens of thousands of people have travelled to a sleepy town in the American west, to witness a rare celestial event.
Warming up over the next few days. Mostly dry in the south, rain at times in the north.