Low carb, the 5:2 diet,detox, cabbage soup... there's no shortage of novelty diet programmes promising to helpyou lose weight fast.
The big question is, do they work? Most do lead to fast sometimes dramatic weight loss, but only for the pounds to creep back on again at the end of the diet.
More worryingly, many fad diets are based on dodgy science or no research at all, prescribing eating practices that are unhealthy and can make you ill.
The British Dietetic Association says there's no "wonder-diet you can follow without some associated nutritional or health risk".
A fad diet is typically a low calorie diet with few foods or an unusual combination of foods.
People can lose weight very quickly initially, but soon get fed up and return to old eating habits, and end up putting the weight back on.
Here are 5 reasons why following the latest novelty diet may not be a good way to lose weight.
Many diets, especially crash diets, are geared to dramatically reducing the number of calories you consume.
"Crash diets make you feel very unwell and unable to function properly," says dietitian Ursula Arens. "Because they're nutritionally unbalanced, crash diets can lead to long-term poor health."
Find out how to start losing weight
Some diets recommend cutting out certain foods, such as meat, fish, wheat or dairy products.
Cutting out certain food groups altogether could prevent you getting the important nutrients and vitamins your body needs to function properly.
You can lose weight without cutting out foods from your diet. The Eatwell Guide shows the different foods we should be eating.
Some diets are very low in carbohydrates (like pasta, bread and rice), which are animportantsource of energy.
While you may lose weight on these types of diets, they're often high in protein and fat, which can make you ill.
Low-carbohydrate diets can also cause side effects such as bad breath, headaches and constipation.
"It's been suggested that the high protein content of these diets 'dampens' the appetite and feelings of hunger," says Arens.
Many low-carbohydrate diets allow you to eat foods high in saturated fat, such as butter, cheese and meat.
Too much saturated fat can raise your cholesterol and increase your risk of heart disease and stroke.
Detox diets are based on the idea that toxins build up in the body and can be removed by eating, or not eating, certain things.
But there's no evidence that toxins build up in our bodies. If they did, we'd feel very ill.
Detox diets may lead to weight loss because they involve restricting calories, cutting out certain foods altogether, such as wheat or dairy, and eating a very limited range of foods.
"Detox diets do not work," says Arens. "They are, in effect, a form of modified fasting."
Some fad diets are based on eating a single food or meal, such as cabbage soup, chocolate or eggs.
Others recommend eating foods only in particular combinations based on your genetic type or blood group.
Often there's little or no evidence to back up these diets, and they can be difficult to keep to in the long term.
"If followed over long periods, these dietscan bevery unbalanced and bad for your health," says Arens. "You may lose weight in the short term, but it's much better to lose weight gradually and to be healthy."
We put on weight when the amount of calories we eat exceeds the amount of calories we burn through normal everyday activities and exercise. Mostadults need toeat less and get more active.
The only way to lose weight healthily and keep it off is to make permanent changes to the way you eat and exercise.
A few small alterations, such as eating less and choosing drinks that are lower in fat, sugar and alcohol, can help youlose weight.
There are also plenty of ways to make physical activity part of your life.
If you're overweight, aim to lose about 5 to 10% of your starting weight by losing 0.5 to 1kg (1 to 2lb) a week.
You should be able to lose this amount if you eat about 500 to 600 fewercalories than you normally consume each day.
An average man needs about 2,500 calories a day and an average woman about 2,000 calories to stay the same weight.
Find out whether it's safe to lose weight fast
Here are 6 simple things you can do to eat healthily and help you lose weight.
You'll find lots more tips and information in our lose weight section.
Regular physical activity will not only help you lose weight, but could also reduce your risk of developing a serious illness.
The amount of physical activity that's recommended depends on your age. Adults aged19 to 64 who are new to activity should aim to build up to 150 minutes of moderate-intensity aerobic activity a week.
Learn more about physical activity guidelines for adults
Beware of buying fake or unlicensed medical products sold as slimming products. Get informed and know what you're buying.
See the article here:
How to diet - NHS