The day after Christmas most of us are already feeling guilty about all that food and drink we have put away since the festive period began.

But before you start reaching for the diet guides, think carefully about what the best method is for shedding the extra pounds and keeping them off.

The BBC is launching a big Fighting Fat, Fighting Fit campaign for the new year, which will look at the British attitude to food, dieting and keeping fit.

There will be:

• healthy recipes from celebrity chef Ainsley Harriott
• medical advice from Dr Mark Porter and Watchdog's Alice Beer
• three Horizon specials on eating disorders, why it is so difficult to lose weight and genetic reasons for obesity
• a six-part documentary following the lives of people with compelling reasons for losing weight
• a programme on the nation's attitudes to food.

Fiona Pitcher, Commissioning Executive for BBC Education, said: "The campaign is all about dispelling the myth of the quick-fix diet. They don't work.

"What does work is healthier eating and just doing some activity every day - using legs instead of wheels. Anything is better than nothing and small changes can make a big difference."

Also included in the campaign is a Fighting Fat, Fighting Fit video, fronted by ex-Olympic athlete Roger Black and geared to the average person.

It takes 10 volunteers through their paces over a 10-week period. All lost weight and said they felt better as a result.

"The secret is to make it a condition of your life. People say they haven't got the time, well, you make the time," says Roger Black.

"What annoys me is that it takes a heart attack or for someone to die who is close to you to make people wake up."

Obesity

According to research, obesity has more than doubled in the UK in the last 10 years.

Currently, 16% of men and 17% of women between 16 and 64 are obese.

And the number is rising. Obesity is measured by body mass index (BMI), that is, your weight divided by your height squared.

People who are obese have BMIs of 30 and over, but those with BMI of 25 and over also need to lose weight.

It is thought that over half the adult population is overweight.

Many people believe that the reason some people are fatter than others is because of differences in metabolic rates, but scientists have shown this to be untrue.

Exercise

Nutritionists say weight problems, particularly among children, are mainly due to lack of exercise and unhealthy eating patterns rather than the amount of food we are eating.

They say we are on average eating less than we did in the past.

But the British Dietetic Association (BDA), which was involved in the BBC campaign, says there is evidence the overweight underestimate how much they eat in surveys.

Spokeswoman Gaynor Bussell says the rushed nature of modern life means many people "graze" instead of sit down to a balanced meal.

This means they are less likely to eat vegetables which need to be cooked.

"Sitting down to a family meal as we do at Christmas is good for you. People have a psychological need to register they have eaten and eating a proper meal is relaxing."

Obesity

Obesity brings an added risk of coronary heart disease, stroke, diabetes, some forms of cancer, depression, osteoarthritis, joint problems and respiratory difficulties.

The statistics might have you running for the nearest diet book or "miracle" drugs such as the new fat-busting treatment orlistat.

But diets rarely work and drugs, even when they do work, have to be combined with changes in eating habits and more exercise.

They may help you to shed pounds in days, but the weight tends to pile back on as soon as the diet ends.

Some 95% of people who lose weight end up regaining it.

Gimmicky diets

The BDA says gimmicky diets, such as eating only proteins, fibre or cabbage soup, are unhelpful and, in some cases, dangerous.

They recommend that people should not follow general diets, but find out what works best for them.

They say each individual has a specific reason why they are putting on weight and any changes to their diet and lifestyle must reflect these factors.

They could range from depression and low self-esteem to unhealthy patterns of eating learnt from an early age and lack of exercise.

The BDA also recommends a gradual, realistic approach to achieving weight loss together with support and close monitoring to help the person stay on the straight and narrow.

Dieticians face an uphill battle against views that dieting involves enduring a life devoid of "naughty but nice" food, such as chocolate and cakes, and a fridge full of celery and carrots.

Balanced diets

The British Nutrition Foundation says it is okay for people to indulge in fatty foods as long as they eat balanced meals, don't eat too much and get enough exercise.

A spokeswoman said: "It is important to get the balance of food right, not just to worry about one thing that is 'bad'.

"Everyone has different needs. If we include a wide variety of foods in our diet it is more likely we will fulfill our different nutritional needs."