Experts have warned that the top five celebrity fad diets should be avoided in the New Year.

The British Dietetic Association (BDA) said that diets followed by the rich and famous were becoming “more extreme” and increasingly involved “medical intervention”.

Dieticians warned there really is “no quick fix” to a slim, trim body for 2013 and said that following celebrity fads could lead to health problems.

Among the most disturbing entries was the Ketogenic Enteral Nutrition Diet (KEN), said to be followed by top fashion models.

The KEN diet involves eating nothing at all. Instead, a liquid formula is administered through a feeding tube inserted through the dieter’s nose. You are attached to a portable pump and liquid bag for ten days and can unhook yourself for only 60 minutes every 24 hours.

BDA consultant dietician Sian Porter described the procedure as “shocking” and something ‘usually reserved for the chronically ill’.

The list also included the bizarre Party Girl IV Drip Diet. Offered at private clinics for about £225 ($340) a time, it involves a high-dose cocktail of vitamins and nutrients administered via a drip of the type used to treat the severely malnourished and clinically ill, supposedly providing a “power boost”.

Sian Porter said: “There is very little evidence that this even works in well people. Even if it did, food and drinking water or other healthy drinks is preferable to having an IV drip inserted into your body.”

She added: “Our concern is that many of these diets are quite invasive. It shows the extreme lengths that people are willing to go to in order to lose weight.

“Eating is a pleasure and people should enjoy their food.”

The carb-free Dukan Diet was named as the worst offender for the third year in a row. The Dukan Diet became the bestselling diet book of all time, with more than a million copies sold in Britain alone. It is credited with Carole Middleton’s svelte figure at her daughter Kate’s wedding to Prince William.

But the BDA described it as “confusing, time-consuming, very rigid” and warned it could cause “lack of energy, constipation and bad breath”.

The Six Weeks To OMG [Oh My God] Diet was dismissed as “six weeks of hell and isolation”. Its London-based creator, Venice A. Fulton, recommends doing exercise first thing in the morning after drinking black coffee, and sitting in a cold bath to burn stored fat.

The BDA attacked as “madness” the increasingly popular Alcorexia or Drunkorexia Diet, which encourages followers to shun calories during the week so that they can binge on alcohol at the weekend. Sian Porter said: “After Christmas, people often look for a quick fix. They see air-brushed celebrities and aspire to look like that.

“But if it looks too good to be true, it usually is. We see new health fads and diets every year but there is no substitute for exercising and a balanced diet.”

BDA view on five diets