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A recipe for ill-health? The trend for fad diets

Sarah Schenker
British Nutrition Foundation
T:020 7404 6504
F:020 74046747

Obesity can lead to premature death, cause considerable ill-health and is one of the largest and fastest-growing public health problems across the world. In England, 17% of men and 21% of women are obese and over half the population is overweight. However, there seems to be more importance given to body image than ever before. For this reason you may find that many of your patients, obese or not, are spending a considerable proportion of their income on information or treatments that claim to help tackle their "weight problem". For the past 20 years the consensus of nutritional advice in the UK has been to eat less fat and more complex carbohydrates, fresh fruit and vegetables. But such an approach is often considered too simple, too boring or too slow, and desperate people will often take desperate measures.

Negative energy balance
So, if you are constantly bombarded with questions from patients asking about the latest fad diets, there is just one thing you should tell them: weight loss is achieved by being in negative energy balance - that is, to lose weight you have to take in less energy than you use up. This is the first law of thermodynamics, and nothing anybody writes in a book, sells you in a tub or promises you with testimonials can change this physical fact of nature.
There are just two ways you can achieve negative energy balance; you can use up more energy than you take in by increasing the amount of daily exercise and physical activity you do, or you can take in less energy than you use up by restricting the amount of calories you consume from food and drink. A combination of the two works best, but remember, nothing can produce miraculous results over night. It is unlikely that the weight was gained quickly, so it is going to take an equally long time to lose again. If a patient is ready to change and is self- motivated, they must accept this and set themselves realistic long-term goals. They must understand that for weight loss to be effective, healthy and sustainable, the weight must be lost slowly, approximately 1kg per week.
Fad diets and calorie consumption
Once this has been established, we then come to the question of what is the best way to reduce calorie consumption, which is where the fad diets come in. They will all work to begin with, because they create an energy deficit through the restriction of foods that are usually eaten. The Atkins diet and other low-carbohydrate diets, such as the Zone and the South Beach diets, restrict basic foods such as bread, pasta, rice, potatoes and breakfast cereals, as well as sugary foods and drinks. So, when you consider what is left, it is not really surprising that fast results are achieved. At best these diets are antisocial (they don't fit in well with family eating), difficult to follow for long periods of time and can be expensive (some of the new ranges of low-carb foods now being produced are not cheap). At worst these diets can be unhealthy and, if taken to extremes, can be dangerous. Cutting out whole food groups means that there is the potential for the diet to become unbalanced. Bread, other cereals and potatoes are valuable sources of fibre, B vitamins, iron, calcium and vitamin C. In the UK it is a statutory requirement that white flour is fortified with niacin, thiamine, iron and calcium, and as such white flour products make a significant contribution to our intake of these nutrients. Extremely low-carbohydrate intakes can lead to the development of ketoacidosis.
A more sensible approach is to reduce the portion size of carbohydrate foods. On their own, bread, rice, pasta and potatoes are not fattening, but they are not eaten alone - they are often eaten with butter, mayonnaise and creamy or fatty sauces. This gives them palatability and makes them easy to overindulge in. Instead, for instance, serve a small portion or rice or pasta (2-3 tablespoons) with a low-fat tomato or lean-meat-based sauce and fill the rest of the plate with plenty of salad or vegetables. This is a much better-balanced meal and still low in calories.

No magic formula
Beware of diets that promise fat loss from specific parts of the body - that is just not possible. There is no magic formula for losing weight from just hips and thighs only. Instead, weight will be lost from all over the body, including the bust. A woman's body in particular, is genetically inclined to gain and lose weight from certain areas such as the face and abdomen before the hips and thighs.
These diets tend to be extremely low in fat, too, but some fat is necessary in the diet to provide essential fatty acids and fat-soluble vitamins, namely vitamins A, D, E and K. So, foods such as semiskimmed milk, lower-fat cheeses, lean meat, oily fish and small amounts of mixed nuts should be eaten in moderation. It is other fatty foods, such as fatty meats, fried foods, crisps, biscuits, cakes and puddings, that are best avoided or eaten only  very occasionally if you are trying to lose weight. 
Other faddy diets include just eating cabbage soup for a week, replacing meals with milkshake drinks and cutting out a set of random foods in line with your blood or body type or even your facial features! The convenient and nutritionally complete milkshakes are fine as a kick-start to a weight loss diet, but they can easily become boring. Real weight loss is achieved only by changing behaviour and eating habits for good. These meal replacement products don't really teach you how to do this, so the danger is that once you stop taking them you may revert back to your old way of eating that made you fat in the first place. As for diets that are designed to match specific body traits or characteristics, there has never been any scientific evidence to support such links, just as there is no evidence to support the theory that you should avoid eating carbohydrates and proteins at the same meal. Lastly, we come to the detox diets, which are supposed to rid the body of "impurities". But nobody has ever been able to say what these supposed impurities actually are. Although detox diets often claim to get rid of cellulite, it's important to realise that cellulite is only fat that's been laid down in a particular way in certain parts of the body - it isn't a disease.

Fad diets will always appeal, especially if they offer a quick fix and oppose current healthy eating strategies. Therefore, to help dissuade patients from following them, explain that ultimately they are wasting their time (and money), because if just one of these diets worked in the long term then we wouldn't be facing the obesity epidemic we currently are.