Warnings about children's unhealthy lifestyles are common, but experts are now showing how junk food fans could look in middle age.
Joanna Buc aged eight - and how she might look at 40
Computer wizardry allowed one family to see how their children will look at 40, if they do not change their habits
Child health experts are overseeing the experiment for the BBC3 show Honey We're Killing the Kids!
Julie Buc, whose children loved eating fried food and sweets, said she was shocked by the images she saw.
'Got to change'
Her children, Jason, aged 10, and Joanna, eight, also enjoyed up to two litres of fizzy drinks each day.
The children were 'aged' using computer technology
They ate their food while watching TV, and did not have a set bedroom routine.
A team of experts, led by child psychologist Kris Murrin, used data from Institute of Child Health-approved medical and scientific tests to collate information on the Stockport family's lifestyle.
They then used high-tech computer graphics to show how the children would look as adults.
Julie said: "All those years that we've been giving the children what they want has got to change and I'm actually quite scared."
The psychologists and nutritionists gave the family a four-week plan on how to change their dietary and living habits.
Julie and her husband Jimmy were told to set bedtimes for 8.30, to eat at the dining table, and to introduce a healthier diet.
Sugary drinks, sweets, fried foods and crisps were banned, and salads, fruits and vegetables were introduced.
Jason said: "It's been really good eating at the table, but I think it's good for the family to tell each other what they've been doing during the day."
The children also took up new hobbies, including ballet, to encourage them to exercise more.
The family were even encouraged to go orienteering together.
At the end of the project, Jimmy Buc said: "The most important things to me are my wife and my children, and I want my children to be successful.
"I hope my children will be now, because we have changed, and there's no way we will be going back."
BBC3 producers are looking for six further families to take part in the project for a series to be transmitted in the autumn.
Anyone who wishes to take part should call 0808 100 4950.