Children take fizzy drink challenge
School pupils in Blackpool, Lancashire, have been seeing if they could give up sugar-laden fizzy drinks for 21 days.
Blackpool has some of the highest rates of overweight and obese children and teenagers in the country.
It is hoped that in the long term the scheme will help the teenagers cut down on how many calories they consume.
BBC News joined a group of the young people to see how they got on.