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Nonsense slimming diets
Who lived on rice, gruel and sago;
'Til much to his bliss,
His physician said this -
To a leg, sir, of mutton you may go.
R S Sharpe
Part 1: Introduction
The Twentieth century more than any other saw a proliferation of slimming ideas. Most diets are based on cutting energy intake, others have made slimming claims for specific items of food. Classic examples are grapefruit, pineapple or fibre. We have had inert fillers, low-calorie this, low-fat that, diet pills and sweaty, plastic clothing. There were Low-Calorie Diets and Very Low Calorie Diets. There were even diets for diet haters. People lost weight and put it on again. Many were harmed, some died.
As some women have realised that low-calorie dieting does not work, they have turned to more drastic measures. They have had their stomachs stapled so that they cannot eat so much; their jaws wired together so that all they can ingest is liquids; their small intestines shortened to reduce the amounts of energy they will absorb; or fat cells removed with liposuction or plastic surgery. These are dangerous and drastic steps which do not always work: one woman who had her jaws wired, explained in an TV interview how she liquidised chocolate bars so that she could eat them. All these measures seem to achieve in the long run is a lot of pain and suffering followed by a loss of morale and self-esteem when they fail.
Before I discuss the nonsense to be found in most modern diets, it would be as well for you to understand more fully the main energy-producing macronutrients. Then you will more readily appreciate that modern diets really are nonsense.
Food may be divided into three main groups: carbohydrates, proteins and fats. All of them provide energy. Any of them, therefore, will provide the body with the energy it needs. But our bodies need nutrients other than energy and this is where the three types of food differ.
Proteins
Proteins are essential to the body, providing the material from which body cells are made and repaired. Proteins are composed of chains of amino acids. There are hundreds of these in nature. Our bodies use around twenty, which can be arranged in an almost infinite number of ways. Amino acids are usually split into two groups: essential and non-essential . The essential amino acids are those that the body cannot make for itself and which must be present in food. There are eight of them. If a protein contains the eight essential amino acids, in the correct proportions (see below), it is called a complete protein; if it does not, it is said to be an incomplete protein .
The ratios of the eight essential amino acids to each other are also important. They should be:
- one part tryptophan
- two parts threonine and phenylalanine
- three parts methionine, lysine, valine and isoleucine
- three and a half parts leucine
- Children also need histidine
Complete proteins are found in meat, fish, eggs and dairy products and also soybean. Animal proteins, which are complete, have a high biological value for us. As we are part of the animal kingdom and composed of similar material to other animals, animal proteins can be utilised by us with the minimum of waste.
Sources of incomplete proteins are cereals, nuts, seeds and legumes. Proportions of amino acids in any one of these types of vegetable food, with the exception of soybean, differ markedly from those needed by us. Maize is deficient in tryptophan, wheat is low in lysine and legumes are low in methionine. Proteins from these vegetable sources are said to be of low biological value . It is necessary, therefore, to combine several vegetable protein sources, fairly accurately, to ensure that the body receives the right amino acid mixture.
In practical terms, it is not too difficult to combine vegetables to meet our bodies' protein requirements. In these circumstances, the real advantage of meat over the vegetables is their associated nutrients: vitamin B-12, vitamin D, iron, calcium and the more complex fatty acids.
As far as weight loss is concerned there is one other advantage to getting your proteins from animal sources: combining the various sources of incomplete proteins to supply all the essential amino acids on a vegetarian diet, could lead to a high intake of carbohydrates.
Your body needs proteins continually but it cannot store those proteins in any quantity. It, therefore, requires that you eat proteins regularly on a daily basis, and at the same meal, in quantities proportional to your size. But they must be complete proteins: if only one of the essential amino acids is missing, the cell rebuilding process will abort.
Although the calorie density of proteins is slightly higher than that of carbohydrates, you will have noticed that slimming diets normally do not restrict the intake of proteins. This is because it has been realised since the 1930s that protein has a slimming effect. Also the body uses proteins generally for repair work, not to provide energy.
Fat
Fat has more than twice as much energy as carbohydrate. Yet we are taught to regard carbohydrate as the primary source of energy. But fat is more than just the best energy provider. It also contains: lipids which are used in the brain and nervous system, without which we become irritable and aggressive; sterols, precursors of a number of hormones (including the sex hormones); the fat-soluble vitamins A, D, E and K. These vitamins can be found in other foods, but without the presence of dietary fat, the body cannot metabolise them. People who are forced to eat lean meat such as rabbit and who are unable to obtain fat from other sources, develop diarrhoea and headache within only a few days. If they continue for any length of time, they become incapable of working.
Carbohydrates
Carbohydrates provide only energy. They have none of the essential components that the body needs to build or repair its tissues. A person fed only carbohydrates would starve to death no matter how much he ate. His body would break down muscle and other body proteins in an attempt to keep the essential organs functioning. At the same time he would put on weight while he died, as the carbohydrate surplus was stored as body fat. Just as we store energy as fat, so plants store energy as starch and sugar. Thus foods of vegetable origin are rich in these carbohydrates.
Your body also requires vitamins, minerals and trace elements. The Western diet provides all these in abundance so long as a mixed diet is eaten. We will not concern ourselves with them, as there is no risk of deficiency except on vegetarian diets or those that are high in bran fibre. Neither of these will be advocated here.
Most foods are a mixture of the three main food types. A notable exception is white table sugar, which is a pure carbohydrate whose chemical name is sucrose. Sucrose has no nutritional value other than as an energy source supplying a meagre 4 kcals per gram.
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