This year's most dangerous fad diets

One involves swapping food and drink for air and sunlight, another encourages eating almost nothing during the week so you can binge on alcohol at the weekend.

These are just two of some of the most dangerous diets followed by celebrities this year.

Ahead of the traditional New Year detox, here is a  list of eating plans everyone should avoid.

1. Breatharian Diet

What’s it all about? Followers of the Breatharian Diet believe they do not need to consume food or drink because they can survive on air and sunlight alone.

Celebrity followers: Actress Michelle Pfeiffer revealed she was in a cult that followed the Breatharian Diet. (Similar to Madonna's alleged Air Diet, when you pretend to eat the food on the plate in front of you and fill up by gulping air.)

Dietican Verdict: Weight loss is guaranteed if anyone attempted to ‘exist’ on this diet but this would also be accompanied by, dehydration, malnutrition and risk of death.

2. Biotyping

What's it all about? This diet involves carefully selecting foods in order to change the body's hormone balance and reduce fat in certain areas.

Celebrity followers: Singer Boy George reportedly attributed his weight loss to this diet.

Dietican Verdict:The diet relies too heavily on supplements and pseudoscience with only a "selective grain of robust science" – that hormones are involved in fat metabolism.

3. Gluten-Free Diet

What’s it all about? Cutting out gluten, the protein found in wheat, barley rye and oats.

Celebrity followers: Gwyneth Paltrow is a committed follower of this diet.

Dietican Verdict: Many foods that contain gluten, like breaded products, pastries, cakes and biscuits, are high in calories, so by avoiding them, many lose weight. However some people believe, wrongly, they can eat as much as they like of gluten-free substitutes like biscuits, sausages and beer – which are also sometimes high in calories.

4. Alcorexia / Drunkorexia Diet

What’s it all about? This diet's followers consume very few calories through food in order to binge-drink alcohol.

For example, if you favour a very low calorie diet, you could be ‘banking’ around 1,500 kcals a day, which then gives you around 11,500 kcals to consume through drink (based on the recommended female diet of 2,000 kcals per day). This amounts to 131 glasses of red wine, and a weekly alcohol intake of 131 units.

The recommended weekly alcohol unit intake is 28 units for men and 21 units for women.

Celebrity followers: Many top models are said to follow this diet.

Dietican Verdict::Followers of a very low calorie diet alone is "madness in itself", as you will most certainly not be getting the calories, vitamins and nutrients your body needs to survive and function. Alcohol also has little nutritional benefit other than calories, and people who drink this amount regularly will inflict immense damage on their body.

5. Dukan Diet

What's it all about? This is a high-protein, lowcarbohydrate diet which is said to promote rapid weight loss.

Celebrity followers: Carole Middleton, the Duchess of Cambridge's mother, is said to have followed this diet.

Dietican Verdict: Even the creator of the diet, Pierre Dukan, who, in 2013 was banned from practising as a GP in France, has warned of associated issues with the diet such as lack of energy, constipation, the need for a vitamin and mineral supplements and bad breath.