Weight Control Diet
Obesity results when a person's intake of calories is greater than the amount needed by the body for energy. Fat supplies about twice as many calories as carbohydrate and protein, and except for alcohol, these three nutrients are the body's only source of calories. Whenever any of these substances are not used for energy, they can be converted into fat and stored in the body. Therefore, two factors must be considered in controlling overweight: the intake of calories and the expenditure of energy. Normal body weight is maintained when these two factors are balanced. To bring about a loss of weight, fewer calories must be taken in and more energy may need to be expended. By the proper regulation of diet and exercise a negative calorie balance can be achieved, and as a result, the energy, or fat, stores in the body will be drawn upon to supply the body's energy needs and produce a loss of weight.
Only a very small percentage of obese individuals can attribute their overweight to endocrine gland disturbances that affect their metabolism. All other overweight people have only their lack of activity and excess food intake to blame.
The desired rate of weight loss for most people is considered to range from 1% to 2 pounds (0.7 to 0.9 kg) per week. However, this rate may vary depending on such factors as water balance, activity, heat loss, and the presence of disease. For most women, diets ranging between 1,200 and 1,500 calories a day will bring about a satisfactory weight loss. For men, the range is between 1,500 and 2,000 calories a day. An intake of less than 1,200 calories is generally not advised since it is likely to be nutritionally inadequate. Because the needs of teen-agers and young children vary greatly from one individual to the next, no general rule can be applied to them and calorie levels should be prescribed individually by a dietitian or doctor.
Pursuing a weight-reduction regimen is difficult for many individuals, and they must be highly motivated in order to persist in the regimen and to maintain a caloric level low enough to bring about a loss of weight. Appetite-depressing drugs, known as anorexigenic drugs, have been used in the management of obesity by some physicians to help the individual reduce his calorie intake to the prescribed level. The use of these drugs, however, should be considered only a part of the overall treatment, which entails re-educating the patient in proper eating and exercise while treating any other factors, such as neuroses, which may be a major cause of the individual's problem. By themselves anorexigenic drugs will not control obesity, and reliance on such drugs, rather than on proper diet, leads to failure in a weight-reduction regimen. Also, there are indications that the unsupervised use of some anorexigenic drugs may be harmful.
In addition to appetite-depressing drugs there are many other products available to overweight people to help them in their attempt to lose weight. These products include methyl cellulose wafers, various high-priced harmless materials often accompanied with bizarre diet plans and other, sometimes not so harmless, materials, usually sold in pill form. By themselves none of these products will cause a reduction in weight.
A variety of special, rather unusual diets have also been reported to be effective in weight reduction. These diets have been known under such names as the grapefruit diet, the drinking man's diet, the 10-day diet, and others. Naturally, if these diets are low enough in calories, and if the individual stays on the diet long enough, he will lose weight. However, the problem with the vast majority of these diets is that they are often made up of only a few foods or a strange assortment of foods, so that they are not nutritionally adequate. Another fault of these fad diets is that certain foods or combinations of foods are erroneously believed to have certain nutritional properties. For example, proponents of the grapefruit diet claim that eating grapefruit before a meat dish helps one lose weight because the acid in the grapefruit will destroy some of the calories of the meat.
In the treatment of people who are underweight, the diet must include more calories than the body needs for energy so that the excess calories can be stored in the body as fat. If the underweight person also suffers from a wasting away of body tissues, a diet high in protein as well as calories may be prescribed.
As a rule, the addition of 500 calories a day above the energy needs of the individual will bring about a gain in weight of about 1 pound (0.5 kg) per week. Sometimes, the daily intake of food may need to be divided into six or eight separate meals in order to reach the desired calorie level.
A sodium-restricted diet is one in which the sodium intake is kept at a specified level. This type of diet is used in treating such diseases as cirrhosis of the liver, toxemia of pregnancy, hypertension (high blood pressure), cardiac insufficiency, and kidney disorders. The average daily intake of sodium for most people is between 5 and 10 grams, most of which is eaten in the form of table salt (sodium chloride). People on sodium-restricted diets, therefore, must greatly reduce their salt intake; this often necessitates a modification in the foods they normally eat. Sometimes a sodium-restricted diet is erroneously described as a "salt-free" or "low-salt" diet. However, many foods, including milk, are natural sources of sodium, so that a diet may be low in salt but not low in sodium.
A person following a sodium-restricted diet must also be aware of the many sources of sodium other than foods. In many communities, the drinking water is high enough in sodium to make a sodium-restricted diet worthless. In such cases, distilled water may have to be used for cooking and drinking purposes. Many medicines also contain sodium, and the continual use of such medicines by a person on a sodium-restricted diet may invalidate the diet. Among the medicines that contain large amounts of sodium are alkalizers and antacids.
As in other quantitatively modified diets, a sodium-restricted diet must always specify the level of sodium. Three sodium-restriction levels have been established by the American Heart Association: severe restriction (500 mg), moderate restriction (1,000 mg), and mild restriction (2,400-4,500 me). In the most severely restricted sodium diets all salt must be eliminated, so that even the usual canned vegetables must be excluded from the diet. An invaluable aid to people on highly restricted sodium diets are the various commercially prepared foods, including milk and canned vegetables, that are low in sodium. These foods, like other foods prepared to meet the requirements of certain modified diets, are called "Dietetic Foods," and they are regulated by the Federal Food and Drug Administration. The labels on these foods must state the level of the substance for which they have been modified. For example, canned vegetables that are advertised to be low in sodium must state on the label the exact amount of sodium per 100 grams or per serving. Therefore, it is important to read the labels on all foods to be included in modified diets, especially in sodium-restricted diets.
A fat-controlled diet is one in which the amount of cholesterol as well as the amount and type of fat are indicated in specific amounts. This type of diet is aimed at reducing the cholesterol level of the blood, and it is often used in the prevention and treatment of atherosclerosis, a major factor in heart disease.
The average American consumes between 40% and 45% of the calories in his diet in the form of fat. In a fat-controlled diet, this percentage is reduced to 35% or less. In addition, the relative amounts of saturated fat and poly-unsaturated fats in the diet are carefully regulated. (For an explanation of the differences between saturated and unsaturated fats, see the article fatty Acros.) Scientific evidence indicates that saturated fats tend to increase the normal blood cholesterol level, while polyun-saturated fats tend to lower the blood cholesterol level. In general, poly unsaturated fats are found in vegetable oils, such as those obtained from samower, cottonseed, corn, soybeans, and sesame seed. Saturated fats are found in animal foods, such as meat, milk, and milk products such as cheese and butter.
For a fat-controlled diet to be effective in lowering the blood cholesterol level, it must contain less saturated fat than polyunsaturated fat. At a 1,200 calorie level, the usual ratio of polyunsaturated fat to saturated fat is 1.1 to 1. At a 1,800 calorie level, the ratio is about 1.3 to 1, and at a 2,400 calorie level, the ratio is about 1.5 to 1.
Although the body does synthesize a certain amount of cholesterol, reducing the patient's intake of cholesterol is extremely important in a fat-controlled diet. Among the foods highest in cholesterol are egg yolk, liver, brain, kidney, sweetbread (thymus), and shellfish. These foods must be either severely restricted or entirely eliminated in order to obtain the best results from a fat-controlled diet. Egg whites may be eaten as much as desired, but egg yolks are usually limited to three or four a week.
Foods to be included in a fat-controlled diet must be prepared without the use of saturated fats, substituting polyunsaturated fats in their place. For example, special margarines high in polyunsaturated fats should be used instead of utter in cooking and eating. Special salad dressings made with oils that are high in polyunsaturated fats should also be used. Meats must be lean and well trimmed of fat, and poultry must have the skin removed. Fresh fish and fish that is not packed in oil are excellent protein-rich foods that should be included in the diet. Skim milk and cheeses made from skim milk are also important in a fat-controlled diet.
Diets for Inborn Errors of Metabolism
Diets for the treatment of inborn errors of metabolism are designed to reduce greatly or eliminate foods containing the particular substance that cannot be properly metabolized by the body. In phenylketonuria (PKU), the amino acid phenylalanine cannot be metabolized normally because the body lacks the enzyme phenylalanine hydroxylase. As a result, phenylalanine and abnormal metabolites accumulate in the body, causing brain damage. In controlling phenylketonuria, the diet is designed to keep the phenylalanine content as low as possible without affecting the growth and development of the infant. In galactosemia, another inborn error of metabolism, the body lacks one of the enzymes necessary in the metabolism of galactose, a component of lactose (milk sugar). In the treatment of this disorder, all foods containing galactose are greatly reduced or completely eliminated from the diet.
Diets for Treating Intestinal Ulcers
Certain disorders of the gastrointestinal tract, such as ulcers and ulcerative colitis, are generally treated with modified diets in which the amount of cellulose and other fibrous material is greatly reduced. This type of diet, known as a low-fiber diet, is designed to reduce the amount of mechanical irritation to the upper gastrointestinal tract (the stomach and small intestine) while also reducing the amount of fecal residue in the large intestine. In the treatment of duodenal and gastric ulcers, however, it has been found that the disorder may be effectively controlled regardless of the type of diet. In these disorders, other factors may be considerably more important than the kind of food ingested. For example, neutralizing gastric acidity with antacid tablets and avoiding stressful situations may control the patient's condition well enough to allow him to eat a normal diet.