Last Updated: Tuesday, 27 November 2007, 08:08 GMT
Do I need to give up junk food?
A burger and chips
'Junk diets' rather than junk food is often the cause of obesity
The answer to how bad junk food is for you depends on how much of it you eat.

According to the experts we consulted in making What's Really In Our Food?, having a burger or pizza now and again as part of a properly balanced diet that includes plenty of vitamins and nutrients is not going to damage your health.

Instead, most of the experts agreed that the real problem lies with what they call "junk diets". This is when people eat junk food to the exclusion of everything else.

Having a sugary breakfast, a burger for lunch and a pizza for dinner every day - and no fruit and vegetables - is the kind of diet that over the long term can lead to serious health problems including Type II diabetes, heart attack and stroke.

Almost one in five children under-15 are currently obese, and if current trends continue, more than half of the adult population could be clinically obese by 2050.

To help us make more informed decisions about what we eat dieticians sometimes refer to what are called "Guideline Daily Amounts" or GDAs for short.

These are daily targets to aim at in order that we do not eat the quantities of food that can lead to health problems.

Guideline daily amounts for men, women and children

Women 2,000 90g 70g 20g 6g
Men 2,500 120g 95g 30g 6g
Children(5-10) 1,800 85 70g 20g 4g

Using this scale it is possible to assess how some types of fast foods can contribute a huge number of calories, salt, fat or sugar in a single portion.

For example, a Burger King double whopper with cheese contains 923 calories. That is almost half what a woman should eat in an entire day.

A muffin from a high street coffee chain can contain 500 calories. This is a fifth of a man's guideline daily amount in one snack.

Equally a single slice of Domino's double decadence cheese and tomato pizza can contain 1.9g of salt, or about a third of the guideline daily amount for both men and women.

With this in mind, the recommendations of the experts we talked to was that we should view junk food as a treat and not a staple.

We should be careful about not eating it too much or too often and try to eat small portions.

And we should also try to eat lots of fruit and vegetables. This is something many fast food companies have already taken on board and are trying to offer a greater range of products.

So if you love junk food - do not worry - you do not have to give it up.

What's Really In Our Food? was broadcast from Monday 26 to Friday 30 November 2007 at 0915 GMT on BBC One.

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