Low-card, low-calorie, detox, cabbage soup... there is no shortage of novelty diet programmes that promise to make you 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.

In 2011, the British Dietetic Association warned against following popular diets such as the Dukan diet, which it said was complicated, not based on scientific evidence and reportedly did not lead to long-term weight loss.

Below are some of the problems with fad diets, plus advice on healthy eating and how to lose weight healthily.

Five reasons to avoid fad diets

Many weight loss diets promise to help you lose weight quickly. Often, these diets focus only on short-term results, so you eventually end up putting the weight back on.

Here are five reasons why following the latest novelty diet may not be a good way to lose weight.

1. Some diets can make you will

Many diets, especially crash diets, are geared to dramatically reducing the number of calories you consume. Crash diets can make you feel very unwell and unable to function properly. Because they are nutritionally unbalanced, crash diet can lead to long-term poor health.

2.Excluding foods is dangerous

Some diets recommend cutting out certain foods, such a meat, fish, wheat or dairy products. Cutting out certain food groups altogether could prevent you from getting the important nutrients and vitamins that your body needs to function properly. You can lose weight without cutting out foods from your diet. The eatwell plate shows the different foods we should be eating.

3. Low-card diets can be high in fat

Some diets, such as the Atkins diet, are very low in carbohydrates (for example pasts, bread and rice), which are an essential source of energy. While you may lose weight on these types on 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. 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 you cholesterol and increase your risk of heart disease and stroke.

4.Detox diets don’t work

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. However, there’s no evidence that toxins build up in our bodies. If they did, we would 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.

5.Cabbage soup, blood group and other fad diets are often far-fetched

Some fad diets are based on eating a single food or meal, such as cabbage soup or raw foods. Others make far-fetched claims, for example that you should cut out certain foods from your based on your bloodtype. Often, there is little of no evidence to back up these claims.

How to lose weight the healthy way

We put on weight when the amount of calories we ear exceeds the amount of calories we burn through normal everyday activities and exercise.

The only way to lose weight healthily and keep it off is to make permanent changed to the way you eat and exercise. A few small alterations, such as eating less and choosing drinks that are low in fat, sugar and alcohol, can help you to lose weight. There are also plenty of ways to make physical activity part of your life.

If you’re overweight, aim to lose about 5-10% of your starting weight by losing 0.5kg-1kg (1lb-2lb) a week. You should be able to lose this amount if you eat about 500 to 600 calories fewer a day than you need.

An average man needs about 2,500 calories a day and an average woman about 2,000 calories to stay the same weight.

Six ways to kick-start your healthy weight loss plan.

Here are six simple things you can do to eat healthily and help you lose weight.

• To reduce the amount of fat you eat, you could trim the fat off meat, drink skimmed or semi-skimmed milk instead of full fat, choose a reduced or low-fat spread and replace cream with low-fat yoghurt.
• Eat wholegrain foods, such as wholemeal bread, brown rice and pasta. They’re digested more slowly than the white varieties, so will help you feel full for longer.
• Don’t skip breakfast. A healthy breakfast will give you the energy you need to start the day, and there’s some evidence that people who eat breakfast regularly are less likely to be overweight.
• Aim to eat at least five portions of a variety of fruit and vegetables a day.
• If you feel like a snack, try having a drink first, such as a glass of water or cup of tea. We often think we’re hungry when really we’re thirsty.
• Swap drinks that are high in calories for lower calorie alternatives. That means drinks that are lower in fat, sugars and alcohol. Swap a sugary fizzy drink for sparkling water with a slice of lemon. Don’t forget that alcohol is high in calories, so cutting down on alcohol can help you to control your weight.

Exercise and weight loss

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 is recommended depends on your age:

• Adults between 19 and 64 who are new to activity should aim to build up to 150 minutes of moderate-intensity aerobic activity a week.