The Dukan Diet

Reviewed by Dietitian, Juliette Kellow BSc RD

If you want to shape up in time for summer the Dukan diet, which claims to help you lose up to half a stone in just five days, might sound tempting. But just what does it involve and is it safe? Dietitian Juliette Kellow investigates…

The Dukan Diet, a ‘breakthrough’ diet book by Dr Pierre Dukan, has sold more than 1.5 million copies and has been a top 10 hit on the French Amazon website for three years. A-listers like Jennifer Lopez, supermodel Gisele Bundchen and Gossip Girl star Jessica Szohr are all said to be fans. And now it’s hopped across the Channel to land on British shores.

What does the Dukan diet involve?

The diet (or regime) is based on four phases, with each one following on from the other. Dr Pierre Dukan believes eating protein is the key to achieving weight loss, so the starting point is a very high protein diet combined with no carbs.

If that sounds similar to the Atkins diet, you’re thinking along the right lines. However, it’s even stricter than Atkins. The Dukan regime really does start with no carbs except for a small amount of oat bran. Even low-carb veggies like spinach and cabbage are off limits at the beginning!

Unlike Atkins, it seriously restricts fat so fried eggs, steaks and chops are not allowed. Instead the Dukan Diet replaces them with lean protein-rich foods. Throughout all the phases, this high protein, no-carb way of eating appears.

Dr Dukan’s theory...

Quite simply protein is a dieter’s friend, whilst fat and carbs are initially the foe. Pierre Dukan puts forward several good reasons to eat more protein-rich foods when trying to lose weight:

• Proteins are composed of long chains of building blocks called amino acids, which are linked with strong bonds that take a lot of effort to break. This means the body has to work really hard to process proteins and so they stay in the stomach longer than fats or carbohydrates. In turn, this means the stomach empties more slowly, helping to keep us fuller for longer so we find it easier to stick to our diet.
• Meanwhile, because the body has to work harder to break down proteins, it burns up more calories in doing so. So for example, when we consume 100 calories from protein, the body uses 30 calories to process it and so in reality we only get 70 calories. In contrast, the body only uses 12 calories to process 100 calories from fat; and just seven calories to process 100 calories from carbs. This means if we eat 1,500 calories of pure protein, in reality we only get 1,050 calories.
• Complementing this high protein intake, carbs should be severely limited because they cause the secretion of insulin. Insulin controls blood sugar levels and encourages the storage of fat.
• Fat needs to be limited because it contains the most calories per gram, and it tends to eaten in combination with carbs like bread and pasta. Protein contains only half the calories of fat – just four calories per gram compared to nine calories per gram of fat.
• Fat only reduces our appetite a little and high intakes are linked with heart disease.

Put simply, Dr Dukan says: “you cannot lose your own fat by eating fat from other sources.”

How do I lose weight without cutting carbs?

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How do I follow the Dukan diet?

There are four phases to the Dukan regime:

Phase 1: The Attack Phase

Made up of protein rich foods that are low in fat. See the ‘Attack Phase’ in more detail.

Phase 2: The Cruise Phase

The Attack Phase with limited added vegetables every other day. See the ‘Cruise Phase’ in more detail.

Phase 3: The Consolidation Phase

To help you keep the weight off. This phase adds a few more vegetables everyday and some fruit. See the ‘Consolidation Phase’ in more detail.

Phase 4: The Stabilisation Phase

The final phase is effectively a lifelong commitment to maintain your weight loss. Most of the time you eat normally, but every Thursday, you follow a pure protein day by eating only foods allowed in the Attack Phase.

Furthermore, you pledge to not use lifts or escalators, walk for 20 minutes a day and have 3tbsp of oat bran daily.

How much weight can I expect to lose?

If you follow the Dukan regime Attack Phase for five days, you can expect to lose up to 7lb although you may achieve 10lb if you are more overweight to start with. If you start with three days of Attack, then you can expect to lose up to 5lb. For a one day Attack, you can expect to shift 2lb.

Once you enter the Cruise Phase of the Dukan diet you can expect your weight loss to stabilise at around 2lb a week.

What can I drink on the Dukan diet?

You should have 1.5 litres of water every day through all the phases. It’s fine to use this in tea, coffee or herbal teas. Ideally, you should opt for mineral water that’s low in sodium, although tap water is still suitable. Diet drinks are also allowed.

This means no alcohol, fruit juices or non diet fizzy drinks.

You need to drink a lot more than usual on this diet because the breakdown of protein creates waste products such as uric acid. Plenty of fluid is needed to help the kidneys eliminate this from the body.

Does the Dukan diet have any side effects?

In the short term you can expect to experience similar side effects to the Atkins diet. When carbohydrates are absent, the body switches to burning fat as its primary source of fuel. This results in the production of substances called ketones, which can cause bad breath, a dry mouth, tiredness, weakness, dizziness, insomnia and nausea.

In fact, Dr Pierre Dukan recommends avoiding any strenuous activities in the Attack Phase as you will probably feel so tired. As for bad breath and a dry mouth, Dr Dukan simply explains they signify you are losing weight and so should be welcomed as proof of success. He recommends drinking more to ease these symptoms.

Constipation may also occur as a consequence of avoiding all carbs with the exception of a small amount of oat bran.

Longer term, this plan may lead to nutritional deficiencies, which cause health problems in later life. For example, if you have 40lb to lose, you could find yourself surviving on nothing but protein and a few vegetables every other day for three to four months. This lack of wholegrains, fruit and vegetables in your diet is likely to lead to a lack of antioxidants. Low intakes of which have been linked with a host of health problems ranging from heart disease and cancer to premature ageing and cataracts.

As a safeguard, Dr Dukan recommends taking multivitamins, but research shows it’s far better to get our nutrients from food rather than pills. Meanwhile, some experts agree that very high intakes of protein may cause kidney problems or weaken bones.

Are there any other bad points?

• There’s absolutely no room for flexibility with the Dukan diet. In the same way a medical condition might be treated with drugs that must be taken, Dr Pierre Dukan believes that people who want to lose weight need a prescribed set of rules and instructions that must be followed.
• The dieting phases of this plan (Attack and Cruise) are extremely limited so chances are the regime will get very boring with the result that many people will give up quickly.
• It’s almost impossible to follow the Dukan Diet if you have a vegetarian diet that avoids dairy and/or eggs.
• From a budget point of view, protein-rich foods such as meat, poultry and fish tend to be more expensive than starchy carbs, fruit and veg.
• This diet fails to teach people about the basic principles of a balanced, healthy diet, which science proves can help keep us healthy and free from disease.

What are the diet’s pros?

• The Dukan diet is designed to enable people to lose considerable amounts of weight very quickly and this can be very motivating.
• It’s very prescriptive and gives dieters a strict set of rules - for some people this can be very effective.
• The lack of choice can make mealtimes easier to plan to some extent, if you can put up with the monotony.
• There’s no need to weigh food or count calories.
• The diet encourages people to cut out refined, processed, fatty and sugary foods and alcohol, all of which are low in vitamins and minerals – definitely a positive move.
• Unlike the Atkins diet, Dukan recommends considerably cutting down on fat and salt, both of which are important health habits to get into.

Juliette’s verdict

This isn’t a diet for the faint hearted. It’s extremely limited in the types of foods that can be eaten during the actual ‘slimming’ phases. The result being that dieters are likely to rapidly fall off the wagon due to mealtime monotony and boredom.

The Dukan diet is incredibly unbalanced and fails to follow healthy eating guidelines, which are designed to keep us free from illness. These guidelines are based on huge amounts of scientific research. In contrast, an extreme diet like this is unlikely to have been the subject of extensive studies and so the long-term affects remain unknown.

Of course this plan will result in weight loss – and rapid weight loss to start with. This is because calories are seriously limited. Whilst in theory you can eat as much protein-rich meat and eggs as you want, ultimately, your taste buds will limit the quantity you eat as you quickly get bored with the same flavours. As a result, chances are you will struggle to eat more than 1,000 calories a day.

A large amount of the weight loss that occurs in the Attack Phase is due to a loss of water, which is bound with a reserve supply of carbohydrate called glycogen in the liver. In the absence of dietary carbs, the body rapidly uses up this supply of glycogen and so you also lose the associated water. Indeed, Dr Dukan says that in the first few days you can often see a slight weight change by the hour and in reality, this can only happen when changes in fluid are occurring.

This also explains why one small deflection from the diet – a jam doughnut, for instance – can show an immediate increase of 3-4lb on the scales. Those glycogen stores are quickly replenished, together with the associated water, which pushes up your weight.

There’s certainly good evidence that protein-rich foods can help us to feel fuller for longer and so have a role to play in controlling our appetite. But increasingly, research is showing that we can achieve an even better hunger-fighter by combining protein-rich foods with high-fibre carbs – for example, scrambled eggs on wholegrain toast. It therefore makes no sense to focus solely on protein. It’s certainly a good idea to start enjoying protein-rich foods at each meal, but not in isolation.

Having oat bran every day is also not something that most health experts would recommend. Oat bran contains phytates, naturally occurring compounds that can bind with minerals such as iron and zinc and reduce their absorption. It’s far better to boost fibre with higher-fibre starchy foods such as wholegrains, pulses and fruit and veg.

On the issue of limiting fruit and veg, health experts have spent years encouraging us to eat 5-a-day and for many very good reasons – reducing the risk of cancer and heart disease, helping to control our weight, and even to keep our skin and hair in good condition. There is a stack of research to show that fruit and veg are good for us, whilst a continual lack of these foods is linked to poorer health. It makes no sense – and in my mind is actually irresponsible – to encourage people to eat fewer of these foods.

What this boils down to is another diet that dramatically reduces calories but packages itself as the latest ‘diet’ breakthrough. It’s the low calorie intake that results in weight loss – and frankly, this can be achieved by eating a mixed diet based on foods from all the four main food groups.
My advice is to give the Dukan diet a miss. Even if you can bear five days of surviving on a diet of meat and eggs, the sweet taste of rapid weight loss will quickly be replaced by bitterness the moment you eat a bowl of cereal or slice of toast and watch the scales return to normal!