The five popular celebrity diets you should never do, according to the British Dietetic Association

Most simply aren't sustainable

(Rex Features)

If December is the month for eating chocolate before 9am, drinking one too many cups of mulled wine every night and scoffing a mince pie every hour, January is the time when many of us feel like we want to nourish our bodies with foods that have slightly higher nutritional value.

We all know that crash diets aren’t a good idea, but that doesn’t stop many of us getting sucked into marketing claims and celebrity testimonials that sound too good to be true.

Now, however, the British Dietetic Association has released a list of the diets they advise the public not to try in the new year - or ever, most likely.

The four diets to avoid are: raw vegan, alkaline, Pioppi and ketogenic (AKA keto). They also warn the public not to take Katie Price’s nutritional supplements.

As Sian Porter from the BDA explains, “If something sounds too good to be true, it probably is.”

The diets to avoid:

Raw vegan

Advocates of serious ‘clean eating’ often follow raw vegan diets, eschewing all food that comes from an animal or anything that has been heated to above 48C.

Megan Fox, Gwyneth Paltrow and Sting have all praised the way of eating.

The rationale is that heating food destroys some of the natural enzymes it contains, meaning the body has to work harder to break down and digest it.

But heat can also bring out the nutrients in some foods, and others cannot be eaten raw.

And according to Porter: “People think that vegan is shorthand for healthy, but it requires careful planning to make sure you don't miss out on important nutrients.”

Alkaline

Popularised by Natasha Corrett of Honestly Healthy, the concept of the alkaline diet is eating foods that are meant to change the pH balance of your body - there is no scientific evidence that this works though.

High-profile fans include the Duchess of York and Tom Brady, and it entails largely avoiding gluten, refined sugar and dairy.

According to Cancer Research UK, however, the pH of your food doesn’t affect the pH of your blood.

“So if it works to lose weight, it's because you're cutting down on calories,” Porter says.

Pioppi

Similar to the Mediterranean diet - the Pioppi diet involves eating low-carb and high-fat, with lots of fruit and veg, fish, olive oil and limited alcohol.

But the diet also advocates intermittent fasting while keeping red meat, starchy carbs and sugar intake low.

However, the creators of the diet have been accused of “hijacking” the Mediterranean diet by the BDA, adding that it’s “ridiculous” to include cauliflower crust pizza or coconut oil in the diet.

“We all know now that a Mediterranean-style diet is one of the most healthy diets to follow. But it's not low carb,” Porter says.

Ketogenic

The ketogenic - or keto - diet is all about eating high-fat, medium protein and very low-carb, and Kim Kardashian, Alec Baldwin and Kobe Bryant have all been linked to it.

In fact, carb intake is meant to come wholly from non-starchy vegetables, nuts and seeds.

It aims to put the body into a state of ketosis, where you’re burning fat stores for energy instead of the glucose from carbohydrates.

But it’s also likely that you’ll lose a lot of fibre from your diet, according to Porter, which is crucial for gut health.

The diet is not recommended: “The sinister thing here is people saying it can cure cancer and things like that - it absolutely cannot!” Porter explains.

Whilst you might lose weight in the short term, it’s very hard to maintain.

Katie Price’s nutritional supplements

As part of her empire, Katie Price has released a supplement and meal replacement range.

The products include powdered mixes for breakfast shakes, meal replacement drinks and recovery and hydration “energy boosters.”

But the BDA does not advise trying to lose weight through meal replacements and appetite suppressants.

“The problem is people need to reintroduce food so you want something you can stick to,” Porter said.