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The 6 Weeks to OMG Diet
This fad diet ,introduced by fitness instructor Venice A Fulton, is popular with A-list stars and encourages competitive weight-loss and extreme diet behaviour such as skipping breakfast, drinking coffee and taking cold baths. BDA Verdict: Six weeks of hell and isolationhttp://blog.upmysport.com
Alcorexia / Drunkorexia Diet
A favourite with top models and other red carpet celebrities, the diet encourages you to eat very few calories during the day/week and ‘save’ all the calories they have not eaten then use them to binge drink alcohol. BDA Verdict: You will not be getting the calories, vitamins and nutrients your body needs to survive and function. In addition, you will feel weak, tired, have no energy and could become very irritable.Reuters
Party Girl’ IV Drip Diet
Rihanna is reportedly a fan of this diet which encourages works by injecting run down celebs with a bag of solution which includes vitamins B and C, magnesium and calcium. BDA Verdict: There is very little evidence that this works well. You also run the risk of having side effects to such as dizziness, infection as well as inflammation of the veins.Rihanna/Twitter
The KEN (Ketogenic Enteral Nutrition) Diet
The drastic weightless regime works involves eating absolutely nothing at all. Instead, for ten days per cycle a liquid formula is dripped directly into the stomach via a plastic tube that goes up the patient’s nose and is taped on to their face. BDA Verdict: The method does not promote healthy eating.One of the side effects is having to take laxatives because this diet provides absolutely no fibre!http://www.apropo.ro
Dukan Diet
The Dukan Diet was invented by French nutritionist and author Pierre Dukan. This complicated four-phase diet works by encouraging a ‘no carb/protein only’ approach to start off. It also focuses on eating more foods that are rich in lean protein to promote weight lost. BDA Verdict: This diet is so confusing, time consuming, very rigid and, in our opinion, so very hard to sustain.http://muscleguide.co.uk

The British Dietetic Association (BDA) has named the Dukan Diet the worst celebrity weight loss plan of 2013.

The diet, which is said to be a firm favourite with stars including Kate Middleton, Jennifer Lopez and Gisele Bundchen, beat the Party Girl IV Drip Diet and the Alcorexia / Drunkorexia Diet to top the BDA's annual list of the Five Worst Celebrity Diets to Avoid in the New Year.

The Dukan Diet recommends consuming only foods rich in protein which it claims promotes weight loss of 7lb a week.

Despites its popularity, experts at the BDA have branded the diet as "confusing, rigid and ineffective" and said that cutting out entire food groups can do more harm than good.

The leading health group said: "There is little solid science behind this. The diet works on restricting foods, calories and portion control. Cutting out food groups is not advisable. 

"This diet is so confusing, time consuming, very rigid and, in our opinion, so very hard to sustain. Even Dukan himself warns of the associated problems like lack of energy, constipation and bad breath. That sounds lovely!!"

Sian Porter, consultant dietician and BDA spokesperson, said: "As much as we all would love it to be the case, there is no magic solution to losing weight and keeping it off long-term. 

"Glamorous images of celebrities saturate our daily media in all forms. These celebs have an army of people to help them to keep looking good, which is essential to their livelihood and plenty of money to do whatever they think it takes. 

"If you have some weight you need to lose, then do it in a healthy, enjoyable and sustainable way.  In the long term this will achieve the results you are after."

IBTimes UK has a closer look at the other diets that made the five worst celebrity diets to avoid in the 2013.