Nonsense slimming diets

Part 4: Twentieth-century diets

The demise of the Banting diet allowed an explosion of diets. In 1967, The Doctor's Quick Weight Loss Diet was published. This gave a diet on which the author claimed weight losses of up to 6 kg (13 pounds) per week. It allowed only lean meats and fish, cottage and skim milk cheeses, and water no fat and no carbohydrates. In 1978 The Complete Scarsdale Medical Diet , co-authored by the same author as the previous book, gave a similar diet. This time it claimed to be able to cause the loss of 9 kg (20 pounds) in two weeks. We know that sustained weight loss of over about 1 kg (2 pounds) a week can be a serious threat to health. Both these diets make unrealistic claims as well as being seriously deficient in a number of fats, vitamins and essential minerals.

The Pritikin diet appeared in 1979, firstly as The Pritikin Program and later as the Maximum Weight Loss Diet . It was written by Nathan Pritikin, an electronic engineer. This vegetarian-based, fat-free diet was not just a slimming diet but one that, Pritikin claimed, would promote a long life. On it, a dieter was allowed to eat as many raw vegetables as she liked. It looked like an unlimited-calorie diet but, as raw vegetables have hardly any energy, you would have to eat so much to provide an excess of energy that, in reality, it too was a low-calorie diet and doomed to failure. It was not much of a success as a life-prolonging diet either, at least to its originator. Without a constant supply of the right nutrients, notably the right fats, the brain cannot function properly. In many of the studies of cholesterol-lowering regimes, there has been a significant increase in the numbers of suicides in those with low blood cholesterol levels. Nathan Pritikin committed suicide in February 1985.

Undeterred by this setback, his son Robert, director of The Pritikin Longevity Center published The New Pritikin Program in 1990.

Diets like this one, which are low in fat, not only cause brain disturbances and severe emotional changes of the sort that may have contributed to Nathan Pritikin's taking his own life, they can also lead to depression, anxiety and frustration. On top of this, they reduce significantly the body's resistance to disease and can ultimately lead to chronic ill health.

Food combining

At the beginning of the century, a Dr. William Harvey Hay hypothesised that the healthy diet was one in which carbohydrates and proteins were not eaten together. Like many nonsense diets the Hay diet sounds plausible at first sight but turns out to be ridiculously bizarre. Hay said that proteins and carbohydrates need quite different conditions in the gut to be digested, which is true. But then he went on to say that for this reason, protein foods and carbohydrate foods should be eaten separately, which is nonsense. Nature obviously hadn't listened to Dr. Hay because foods are not made exclusively of protein or carbohydrate, they are mixtures of both. Bread, for example, is listed as 'carbohydrate' yet it has a significant protein content. Beans, on the other hand, are listed as 'protein', yet they contain up to three times as much carbohydrate.

Vegetable sources of protein tend to be incomplete, lacking some of the essential amino acids. However, the body requires all the essential amino acids and it needs them all at the same time: it is no good eating them many hours apart. Effective nutritious combinations include: baked beans on toast, bread and cheese, meat and potatoes, milk and rice pudding all of which, according to Hay, should not be combined.

There is an American diet that doesn't combine different foods: The Cabbage Soup diet. It works like this: one day you have vegetable (cabbage) soup, the next you have bananas, the next salad, the next eggs, the next only carbohydrates, then you repeat it. This one is dangerously protein deficient yet it has been around for decades.

The Hay diet was a 'health' diet, not a slimming diet, and any weight lost on it was purely as a result of calorie restriction and by taking Dr. Hay's advice to cut out sugar and other refined carbohydrates. The infamous Beverly Hills Diet , published in 1981 was a slimming diet also based on food combining. It looked similar to the Hay diet, but it had a subtle twist. The author, who trained in drama, says that foods should be eaten in combinations that do not "fight one another, digestively speaking". Like Hay, she claims that as proteins and carbohydrates fight, they should not be eaten together.

The subtle twist is her belief that this fighting causes food to remain undigested and get 'stuck' in the body. It is accumulations of food stuck in this way, she maintains, that make us put on weight. She claims that if foods are combined properly so that they do not fight, they will be processed properly and we will not gain weight. It is, of course, utter nonsense. All undigested food passes through and ends up in the lavatory. It is only when food is fully digested that it can be absorbed and cause weight gain.

The Beverly Hills diet's author also advocates eating fruits such as papaya and pineapple as, she claims, they have 'fat burning enzymes' that work on body fat. This again is arrant nonsense fruit enzymes are proteins that are broken down in the gut long before they get anywhere near fatty body tissue. Such a diet as this is much more likely to cause severe diarrhoea and mineral loss. In a later book, the author refers to the Beverly Hills Diet in terms of the Chinese Yin and Yang philosophy. This is the basis of the extreme Zen Macrobiotic Diet which is so nutritionally unbalanced it has caused scurvy, kidney failure and death.

One food only diets

The Beverly Hills Diet tended to be a one-type-of-food-only diet. There were several others including the banana-only diet, the fish-only diet, the juices-only diet and the yogurt-only diet.

The next diet that came along in 1982, the F-Plan Diet , was also based on one ingredient. In this case it was not a food but a non-food the totally inedible dietary fibre. Audrey Eyton's F-Plan effectively doubles the intake of dietary fibre by adding bran to just about everything. This, she says, gives a feeling of fullness and a consequent loss of appetite. But this feeling is distinctly ephemeral. Bran moves through the gut faster than real food and the effect is soon lost. The neuro-chemical sensors in the duodenum also recognise that what is passing has little nutritional content and the appetite is not switched off. It is not the fibre in the F-Plan Diet that does the work. The F-Plan is just like all the others a low-calorie diet. Indeed, Eyton admits this: she states in her book: "Never let anyone, or any diet, convince you that calories don't count in achieving weight loss. They do. They are what slimming is all about."

And there is more to this one. Audrey Eyton is not the only 'expert' to recommend fibre as a means of losing weight. But it has dangers. One of the most used fibres is guar gum. In 1990 the American Food and Drugs Administration proposed to ban guar gum in non-prescription products because of fears over its safety.

And while an increase in fibre has been extolled for improving blood glucose control, the amount of fibre needed to do this is so high as to preclude its incorporation into a palatable or acceptable diet. In many of the studies that tested fibre in obesity, any weight lost was due to the gastric distress that many subjects experienced when they switched to the high-fibre diets.

Most studies are not well controlled. In one that was, researchers found that dietary fibre had no effect on either blood glucose or insulin.