The survey has also unveiled the ignorance of children of both sexes about what they need to eat to be healthy.

The survey by Sainsbury's also revealed that though only 14% of teenage boys admitted to dieting, a quarter of them consume less than 800 calories a day which represents just a third of their recommended daily amount.

Half of all teenagers also wrongly estimated the guideline daily amount of calories for an adult woman 2,000 and man 2,500.

Nevertheless when asked what constituted a healthy diet, 98% of teenagers believe they know and 76% say they consider their diet to be healthy.

But the vast majority (85%) of young teenagers are not eating the government recommended intake of fruit and vegetables.

Sainsbury's youth diet survey is an attempt to examine some of the key issues surrounding diet, exercise and food for young people.

Sainsbury's nutritionist, Charlotte Parker says the results demonstrate that teenagers are struggling to understand what constitutes a balanced diet.

She says combined with the issue of childhood obesity in the UK, it is clear that both teenagers and their families need help.

Sainsbury's has arranged a summit between teenagers, government figures and its chief executive Justin King to tackle issues including junk food, diet and exercise.

Mr King says the company wants teenagers to help them develop practical suggestions and new ideas for young people and their families so they can make informed choices about their health and the food they eat.

Lawyers for the man say they will challenge any extension of the order using human rights legislation.

The HPA are tracing those who came into contact with the man but point out that it takes prolonged and close contact with a sufferer to contract the disease.

Rochdale health officials say the man is now undergoing treatment for the disease.

Although anyone can get TB, it is more likely if you already have another disease, have poor diet and live in overcrowded or sub-standard housing.

Symptoms of active primary TB include: a persistent cough - there may also be lots of phlegm which is sometimes bloodstained, swollen glands, especially in the neck, tiredness, loss of appetite and weight, night sweats, chest pain on breathing in caused by inflammation of the membranes lining the lungs (pleurisy).