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In the mind of most Americans, protein has almost a glamorous image, as the essence of nutrition.
We pay very little attention to how much we actually need based on our biological individuality. This amount varies with our weight, age, and the amount of stress we are under. Pregnant and lactating women also have increased protein needs.
While meat is an excellent source of complete protein and B vitamins, the typical American diet, with its emphasis on beef, pork, and processed meats, has serious drawbacks. Marbled beef, long considered the prestige meat, is high in saturated fats, as are pork and processed meats. Beef cattle are fed a wide range of growth-stimulating hormones, antibiotics, and tranquilizers. DES, now banned because of its carcinogenic effects, was one of these hormones. But there remain nearly 3,000 chemicals with which it is still legal to douse cattle, and any of these can affect your health. Antibiotics, for example, can alter your intestinal flora, and can become ineffectual when taken repeatedly. In addition, pesticides and other chemicals from cattle feed concentrate in the animals' flesh (particularly in the liver).
Finally, overreliance on protein at the expense of high-fiber foods (grains, beans, fibers, fruit) can cause constipation, diverticulitis, cancer of the colon, and other diseases of the intestines.
Dangers of a High-Protein Weight-Loss Diet
The teenage daughter sitting at the table is one of twenty million Americans who are regularly on high-protein crash reducing diets. She is under the impression that by eating a great deal of protein, she is consuming a minimum amount ofcalories, and so will lose weight. Nothing could be further from the truth. In point of fact, eight ounces of beef contains upward of 500 calories, because beef is only approximately 22 percent protein. It contains an appreciable amount of fat, and the rest is water. She could be eating three or four giant salads, including several vegetables, raw or cooked, crammed with high quantities of nourishing vitamins and minerals, for 300 to 400 calories. They would also provide her with adequate fiber bulk, which would make her feel full, in addition to aiding in peristalsis. Instead, she is following one of the many fad diets which have made small fortunes for their promoters while being of dubious benefit to their followers. (There are lots of high-protein diets; they've been around for generations now, always marketed as brand new. With all the mystique attached to protein by the American food industry, it is hardly surprising that protein should be touted as having magical weight-loss properties.)
She may or may not lose weight on whichever high-protein, low-carbohydrate diet she is trying tonight. But more important, what risks is she taking with the diet?
To begin with, a diet of all-the-meat-she-wants but little or no bread, vegetables, or fruit is seriously imbalanced nutritionally. She is losing all the benefits of fiber for health and for the feeling of fullness it brings without excessive calories. The diet is also forcing her body to use protein both from her food intake and the catabolism (breaking down) of her lean muscle tissue for the purpose to which it is least suited: providing energy.
As she read in the book that advised her to go on this high-protein diet, her body is in a state similar to that of starvation, called "ketosis." All the fat she is eating, along with the meat, is causing her body to produce compounds called ketones. At low levels ketones are relatively harmless. But eating too little carbohydrates is causing some toxicity effects. She's pleased to note that she's not particularly hungry--in fact, she feels somewhat nauseous on this diet. This is one effect of those ketones. There are at least forty known cases--as of 1977--of people on high-protein, low-carbohydrate diets (most using liquid protein) dying. The diet can contribute to a host of medical problems.
Is she losing weight effectively on this low-carbohydrate diet? There is some evidence that her body is primarily excreting water and salt, especially at the beginning of the diet. While losing several pounds the first few days has been encouraging, this probably won't last for long. For losing weight steadily and over the long term, she would do just as well on a diet high in complex carbohydrates and much lower in saturated fats; or on the traditional, balanced, low-calorie diet.
If she keeps up the diet long enough, she may be increasing her risk of heart disease. Meat, butter, and other foods high in saturated fats, cholesterol, and sodium have been implicated as contributors to coronary heart disease.
She is lucky that she is on a high-protein diet involving food rather than one involving liquid protein, however. Such a diet can also cause serious damage to your health. The liquid protein, usually from collagen or gelatin, is inferior to that found in eggs, dairy products, or meat. Several obese women died after following the liquid protein diet; it is strongly discouraged.
Challenging the Theory Behind High-Protein Diets
Both of these diets are based on the concept, first proposed in 1903, of "protein stores." Some of the promoters of these diets claim the body isn't hurt by eating excess protein--that it just stores the excess away for future use. But no one has yet discovered where the protein is stored; nor has the existence of "protein stores" been established in controlled experiments with human subjects. In fact, we have no protein stores as we do for fat and carbohydrate.
This means that the body must work overtime to dispose of excess protein. This can be quite stressful--especially on the kidneys. When the body metabolizes protein, a waste product called urea builds up in the blood. It has to be excreted through the kidneys. They need extra water to do the job, and can be harmed if they don't get it. It's especially dangerous for older people, whose kidneys may be weak to begin with, to eat too much protein. As we age, our kidney function decreases, yet grandmother is eating almost as much meat as her granddaughter on the high-protein diet!
The whole high-protein controversy spotlights once again the American tendency to fixate on quantity and forget about quality. No one nutrient group is intrinsically harmful or beneficial. What is important is the specific content of a particular food. Twenty-five grams of protein from poached eggs on whole grain bread have far more nutritional value than fifty grams from a poor-quality gelatin drink. They provide fiber, B vitamins, and minerals in addition to their protein content.
The typical American protein, fat, and sugar-laden diet leads many people, invariably, to become overweight.
Because we think so highly of protein, many people experiment with the high-protein, low-carbohydrate diets which become popular every few years.
These diets are often high in calories, because of meat's fat content; fresh vegetables and salads are much lighter fare, and their bulk (fiber), missing from low-carbohydrate diets, makes them filling.
A long-term high-protein diet can cause heart disease (because of the saturated fats) and kidney problems (due to the difficulty of disposing of urea, a waste product of protein metabolism and excess sodium).
There are several theories of weight loss on high-protein diets. The body goes into ketosis when not enough carbohydrates are consumed, causing it to use fats and also body protein for energy. High levels of ketones can be slightly toxic. The idea of protein stores is now discredited--your body has no extra stores of protein. That is why, normally, it uses carbohydrates and fats as fuel, protecting the protein used in building cells and excreting excess protein.