Parenting classes teaching people to be more strict with their children could reverse Britain's obesity epidemic, experts say.
Parents on the eight-week courses are encouraged to show their children they are 'in charge', in a bid to make families more healthy.
For example, instead of asking children what they would like to eat, youngsters are offered a choice of only carrots or peas.
Since the classes were introduced a decade ago, the rise in obesity levels has been almost entirely reversed among four and five-year-olds in Leeds.
One of the first cities to adopt this parenting approach to reduce obesity, it has seen the proportion of pre-school children who are obese fall from 9.4 per cent around 2014 to 8.8 per cent in the three years to 2016.
Experts say this is 'unprecedented' and a vast improvement on the continuing obesity crisis in England, where over the same period the obesity rate stayed largely the same.
Parents on the eight-week courses are encouraged to show their children they are 'in charge', in a bid to make families more healthy
In the country as a whole, 9.4 per cent of four and five-year-olds remained obese.
The results are important because child obesity is on the rise, with more than a third of children leaving primary school overweight or obese.
Professor Susan Jebb, who led a study on the strategy from the University of Oxford, said: 'The most dramatic thing is if you look at it by deprivation, the most deprived group in Leeds is doing especially well. That is astonishing.
'Going into parenting behaviour is a promising approach.
'If you catch very young children, parents have a heck of a lot of control over their lifestyle. Under fives don't pop to the shop to buy something.
'Their every meal is what parents and carers provide.'
British teenagers aged 15 to 19 have the fifth highest obesity level in the developed world, the study also showed
HENRY is all about parents giving children choices while showing they are in charge:
Don't say to your child: What do you want to eat?
Do say: Do you want carrots or broccoli?
Don't say to your child: Are you ready for bed?
Do say: It's bedtime - where do you want to read your bedtime story?
Don't say to your child: Thank you for being helpful - have some chocolate as a reward.
Do say: Thank you for being helpful - as a reward, add another brick to the tower we are building.
Don't say to your child: Switch off the television.
Do say: Shall I switch off the television or would you like to?
The two-month HENRY programme, which stands for 'Health, Exercise, Nutrition for the Really Young', has been rolled out in 34 local authority areas since 2008.
It is aimed at giving parents the emotional skills to help their children be healthier, covering everything from diet to exercise, screen time and bedtimes, as well as helping them resist 'pester power'.
Kim Roberts, chief executive of the charity HENRY, said: 'Authoritarian parenting is when children are told what to eat and what to do, such as being banned from leaving the table until they have eaten their sprouts.
'Permissive parenting is asking children what they want to do.
'But HENRY encourages a third approach known as authoritative parenting, where parents make it clear they are in charge, but also respond to their children.'
The parenting classes saw obesity rates for deprived children plummet from 11.5 to 10.5per cent in Leeds.
English children are fatter than ever – official data revealed in October that one in every 25 10 to 11-year-olds are severely obese, the fattest possible category.
And out of around 556,000 children of primary school-leaving age in the UK, 170,000 are overweight to some degree, figures showed in May.
More than one in ever five 11-year-olds are obese – equivalent to around 111,000 children – and being so fat means they are more likely to develop type 2 diabetes, heart disease, cancer or have a stroke.
The Royal College of Paediatrics and Child Health say children should be weighed every year at school because 'danger is on the horizon' and the UK is lagging behind the rest of the EU in tackling obesity.
Experts have also warned children gain weight 'at a drastic rate' when they're at school.
Sugar in food is known to be contributing to the