The popular Dukan diet has been slammed as “ineffective and without scientific basis”, The Daily Telegraph has today reported. The newspaper says that the British Dietetic Association has criticised a range of celebrity diets, including the Dukan diet rumoured to be used by Kate Middleton.
Anticipating the huge surge in dieting around Christmas and New Year, the association has drawn up a list of five 'fad diets' that slimmers may be considering after reading about celebrities using them to stay trim. According to the British Dietetic Association (BDA), the top diets to avoid are:
- The Dukan diet: this restrictive, complicated diet includes phases of eating only protein and avoiding a number of foods. Kate Middleton and Jennifer Lopez are reported to be fans. However, the BDA says ‘there is absolutely no solid science behind this at all’ and cutting out food groups is not advisable. They point out that even Dr Dukan himself warns of side effects such as a lack of energy, constipation and bad breath.
- Alcorexia: this is where people heavily restrict what they eat during the day so they can save calories and drink more alcohol without gaining weight. The BDA says, ‘to do this in order to ‘bank’ your calories so you can go a use them on alcohol is pure madness and could easily result in alcohol poisoning and even death’. The association says it has had a worrying rise in press enquiries about this dangerous practice.
- *The Blood Group diet: *this diet restricts what people can eat based on their blood group. Its premise is that only certain blood groups can handle certain foods. Cheryl Cole and Sir Cliff Richard are rumoured to be devotees. The BDA says the diet ‘is completely based on pseudo-science’, and could lead to serious nutrient deficiencies.
- The Raw Food Diet: as its name suggests, this diet, reportedly followed by Demi Moore and Natalie Portman, focuses on eating food raw but also on eating only unpasteurised dairy products. Although some vegetables are more nutritious when eaten raw, the BDA points out that it means many nutritious foods cannot be eaten at all, and that it carries a risk of food poisoning.
- The Baby Food diet: this diet, made famous by reports that Lady Gaga is a fan, calls for people to eat up to 14 jars of puree or baby food each day. The BDA says that it is a restrictive diet as baby food provides few calories and lacks fibre or texture. Without chewing on firmer food at meal times you may be left feeling hungry.
Sian Porter, consultant dietitian and spokesperson for the BDA says, ‘Sadly, there is no magic wand you can wave. 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.’
But isn't there proof supporting the Dukan diet?
Among the diets chosen by the BDA, the Dukan diet stands out as the most popular, with millions of people around the world having tried it in recent years. In particular, the interest has grown even further since newspapers reported that Kate and Pippa Middleton may have used the diet to slim down before the royal wedding.
However, while the diet is hugely popular it has come under some serious criticism from organisations such as the BDA. In addition to their damning conclusion that there is ‘absolutely no solid science behind this at all’, a respected French health publication has said they could not find any scientific reports that supported a long-term impact from the diet.
Unable to find this evidence, Le Journal des Femmes Sante surveyed followers of the diet and found that despite rapidly losing weight in the initial, restrictive phases of the diet, the vast majority regained all the weight they had lost within the next few years.
In addition, given the rise of restrictive diets such as the Dukan plan, the French Agency for Food, Environmental and Occupational Health and Safety reportedly published warnings against the nutritional deficiencies that restrictive diets might cause. The agency also highlighted the potential long-term effects of these restrictive diets, especially the tendency for most restrictive dieters to regain the weight they had lost.
Does the Dukan diet work in the long term?
While many Dukan diet users have reported impressive weight loss results in the initial phases of the diet, many organisations feel there is a lack of solid scientific evidence on whether the Dukan diet is sustainable and effective in the long term.
While survey results must be approached cautiously, as they are less robust than scientific studies, the results gathered by Le Journal des Femmes Sante give perhaps the best indication to date on whether the Dukan diet actually produces lasting results. Based on the survey of nearly 5,000 Dukan dieters:
- 35% of respondents regained all the weight they had lost less than a year after starting the diet
- 48% regained the weight within a year
- 64% within two years
- 70% within three years
- 80% over a period of more than four years
The study's authors say, 'These results explain why people give positive feedback when interviewed during the first year. They also confirm that in the medium and long term, the Dukan diet is no more efficient than any of the other restrictive diets.
'When the diet fails, the weight regain accelerates after six months. For 50% of respondents it occurs most of the time between six months and two years after the start of the diet.'
The authors of the report say that these results are consistent those from a 2009 survey on restrictive diets conducted by the French health authorities.
What might stop the Dukan diet working in the long-term?
Again, the reported lack of long-term research means it is difficult to tell, but the report offers some insight from both dieters and medical experts.
The stabilisation phase
Around two-thirds of people that failed to complete the diet said they did not get through the 'stabilisation phase' of the diet, the fourth and final stage in the regime. It includes features such as a dedicated protein day and the inclusion of simple exercises. Some detractors of the diet have said that it is too hard to follow and that adjusting to this phase is too difficult.
The yo-yo effect
The report also featured the opinions of a panel of doctors and dietitians, who were generally critical of the Dukan diet and the effect it can have on the body. In particular, they say that the restrictive diet changes the body's metabolism (the way the body stores and uses energy), which can lead to a yo-yo effect, where dieters constantly lose and regain weight.
Dr Marie-Josée Leblanc says, ‘It’s very uncommon for this type of diet to remain efficient in the medium run. By imposing such an abrupt decrease in the energy supplied to the body, you force it to adapt and it learns to function on fewer calories. As a result, when you revert to a normal diet again, your body receives way too many calories in comparison to what it needs. It will then start to store this energy as fat. It’s the so-called yo-yo effect.’
The psychological effect
Professor Monique Romon argues that the initial success seen with many diets such as the Dukan plan is that they can lead to negative feelings once weight loss starts to slow down: 'Most of the time, overweight or obese people start a diet in order to reach an ideal weight they’ve always dreamed of. But in every diet, there are steps in the weight loss, with plateaus that are normal. As soon as they think it doesn’t work anymore, their motivation decreases and they develop a feeling of guilt and they think they won’t be able to make it. Therefore, they stop the diet, then start another one, then stop, etc.'
Surely there is no harm in trying it though?
The lack of long-term research makes it hard to tell but the authors of the report stress the possibility that restrictive diets can cause nutrient deficiencies, diabetes, cardiovascular disease and bowel problems. They say that restrictive diets:
- lack fibre, which is likely to cause bowel problems
- are high in salt, with some providing 6g of sodium a day (UK guidelines suggest eating no more that 2.4g)
- are often poor sources of essential vitamins and minerals, particularly calcium
- are often followed by weight gain around the waist. The authors say that is associated with diabetes, high blood pressure, heart disease and liver problems.
What proven diets are there?
There are a number of well-researched weight loss methods that tend to focus on developing a slower, sustainable way of losing weight than can also be kept off in the future. They tend to involve eating sensibly and exercising rather than rapid weight loss and drastic rules denying you from eating what you want. Some methods include:
- Setting up a weight loss plan with your GP: a free and effective way to set yourself safe weight loss targets with expert help from your doctor
- Slimming clubs such as Weight Watchers and Slimming world, which offer group meetings, sustainable weight loss programmes and online support
- Sustainable whole-life diet plans such as the US government's hugely successful DASH diet, an evidence-based approach that emphasises simple dietary changes that can help people lose weight and keep it off. The diet also has a specific emphasis on combating health problems such as high blood pressure and diabetes
For other weight loss ideas try our section on dieting tips and real-life weight loss stories.