"MORE PEOPLE ARE KILLED BY OVEREATING AND DRINKING THAN BY THE SWORD."
INTRODUCTION
In our society, where slim and trim are essential components of being attractive, a great deal of emphasis is placed on controlling body weight. In addition, increased public awareness of the pathological impact of excessive weight has reinforced this obsession. According to recent studies, obesity is now the second-leading cause of preventable death in the United States (the leading cause is smoking). It is estimated that we annually spend more than $100 billion dollars to treat cardiovascular disease, cancer and diabetes caused by obesity.
Obesity can be defined as the pathological accumulation of fat in excess of 20% of the body's needs. It has been estimated that obesity affects more than 33% of American adults (up from 25% in 1960) and as many as 25% of teens and children. Much effort has been devoted to elucidate the cause of obesity. Although many questions concerning obesity are yet unresolved, some factors which contribute to its development are:
- change in physical activity (e.g., decrease in physical exercise, relative to food consumption)
- genetic predisposition (efficiency in calorie utilization by the body appears to be an inherited trait): genetic factors may play a significant role in 30-80% obesity situations
- environmental factors
- early eating patterns (e.g., parents encourage children to overeat).
- psychological factors (more than 90% of the obese population have associated psychological problems)
- set point theory (an adult's body weight is maintained at a relatively stable level for long periods of time by feedback mechanisms controlled by the brain)
Although organic disorders, such as brain tumors or endocrine (e.g., thyroid problems), can also lead to obesity, such problems account for relatively few cases of obesity (<1% of total).
According to the National Heart, Lung and Blood Institute (NHLBI), in 1999, almost 108 million adult Americans were overweight or obese. Carrying extra weight puts an individual at risk for developing many diseases, especially heart disease, stroke, diabetes, and cancer. Losing this weight helps to prevent and control these diseases. Hence, the NHLBI put forth guidelines suggesting a new approach for the measurement of overweight and obesity and a set of steps for safe and effective weight loss. Among these guidelines, Institute proposed the use of a body mass index (BMI) to assess obesity because the index is simple, correlates to fatness, and applies to both men and women. To determine BMI, an individual takes his/her weight in kilograms divided by his/her height in meters, squared. A BMI of 25 to 29.9 is considered overweight and one 30 or above is considered obese (see "Assessing Your Risk" box for further information on NHLBI guidelines).
Assessing Your Risk
According to National Heart, Blood and Lung Institute (NHBLI) guidelines, assessment of overweight involves using three key measures:
1. Body Mass Index (BMI) BMI scores estimate total body fat. A BMI score below 18.5 suggests that a person is underweight, 18.5 - 24.9 indicates "normal" weight, 25.0 - 29.9 indicates "overweight," and 30.0 and above indicates obesity.
2. Waist Circumference Waist circumference is determined by placing a measuring tape snugly around the waist. It is a good indicator of abdominal fat which is another predictor of risk for developing risk factors for heart disease and other diseases. This risk increases with a waist measurement of over 40 inches in men and over 35 inches in women
3. Other Risk Factors Besides being overweight or obese, there are additional risk factors to consider including high blood pressure (hypertension), high LDL-cholesterol ("bad" cholesterol), low HDL-cholesterol ("good" cholesterol), high triglycerides, high blood glucose (sugar), family history of premature heart disease, physical inactivity and cigarette smoking
The BMI is a measure of weight relative to your height and waist circumference measures abdominal fat. Combining these with information about additional risk factors indicates a person's risk for developing obesity-associated diseases. For people who are considered obese (BMI greater than or equal to 30) or those who are overweight (BMI of 25 to 29.9) and have two or more risk factors, the NHLBI recommends weight loss. Even a small weight loss (just 10 percent of current weight) will help lower an individual's risk of developing diseases associated with obesity. Patients who are overweight, do not have a high waist measurement, and have less than 2 risk factors may need to prevent further weight gain rather than lose weight. Individuals should speak with his/her physician to determine if he/she is at an increased risk and if he/she should lose weight.
In order to avoid the social and medical consequences of obesity, overweight individuals are continually involved in programs designed to shed unwanted fat. In fact, in 1996 over $33 billion were spent by people in this country on products and programs to lose unwanted pounds.
WEIGHT REDUCTION
Historically, people have viewed obesity as a consequence of poor self control. It was thought that those suffering from excessive weight were lazy and self-indulgent, lacking the will power to adequately exercise and control their eating habits. Although overeating is commonly associated with obesity, other factors such as inherited psychological traits, metabolism, exercise and environment can also be important contributors; thus, changing eating habits alone is rarely sufficient to resolve an overweight problem. It is essential to appreciate that obesity is typically a chronic disease and not just an attitude problem and that success likely will require lifetime changes and treatment.
Helping overweight Americans to alter their eating habits and life styles in order to lose weight permanently has not been particularly successful. Many weight-loss approaches can help reduce body fat for the short-term (weeks to a year); however, some experts claim that most persons trained in behavioral self-management of obesity experience relapse to old behaviors and former, and often even greater, weight. Only about 5% show significant and lasting weight losses for more than 5 years. Experience has shown that many overeaters are destined for cycles of failure prompted by social pressure to be thin followed by restrictive dieting, which leads to a backlash of hunger. This in turn results in more overeating and weight gain, followed by more restrictive dieting and social pressure to be thin. With multiple unsuccessful attempts to lose weight comes frustration and a sense of resignation that nothing can really be done to correct the obesity problem. The following are current strategies often used to deal with obesity. The rationale for these approaches are discussed.
ALTERING EATING HABITS
In contrast, organic disorders and diseases, such as brain tumors or thyroid gland problems rarely play a role in excessive weight gain. Consequently, effective therapy for most obese persons depends mainly on a change in life style rather than some exotic therapeutic procedure or surgery. The body can utilize stored fat as a source of energy (i.e., calories) but these fat stores are used only when the body is unable to meet its energy needs with the daily food intake. Thus, if body fat is to be eliminated, the calories supplied by the diet must be significantly less than the needs of the body.
Experts caution that diets used to lose weight can be damaging to the health if nutritionally deficient. An illustration of this danger was the liquid protein diet. The FDA reported more than 60 deaths that were associated with the use of the liquid dieting approach. Safe diets must include food which provides all the nutritional essentials, yet has low caloric content.
As a rule, an effective, intelligent, and safe diet can be implemented for almost every person suffering from obesity. The diet should be individualized to address the individual needs of each patient and include:
- at least 1,200 calories per day
- a variety of foods from the four food groups
- carbohydrates for at least 40% of the total calorie intake
- gradual weight loss of no more than one to two pounds each week (rapid weight loss can be dangerous and likely temporary)
- menus composed of common foods that are easy to buy and prepare
A seemingly endless barrage of commercial diets have been, and will continue to be, promoted for dramatic, rapid weight reduction. These diets appeal to the impatient obese individual who wants to shed the unwanted pounds quickly. Such approaches promise a thinner and more attractive you in a short time with very little effort. These commercial diets are characterized by unsubstantiated promises, understatements of personal sacrifice and substantial profits for the promoters. Typical fad diets tend to fall into one of the following categories:
Stomach Stuffers: These diets consist of substances, such as bran, that are low in calories but, when combined with water in the stomach, they expand, thus giving a full feeling that suppresses the appetite.
Single Food: These diets are based on consuming only one or two different types of foods (i.e., lettuce or cottage cheese). This approach to dieting often leads to malnutrition, not to mention boredom. These types of diets come and go very quickly.
High protein/low carbohydrate: The basis for these diets is that nutritional requirements are supplied by doses of high protein, while the lack of carbohydrates (sugars) forces the body to breakdown its own stores of fat for its caloric needs. If used for long periods of time, these diets can cause serious health problems.
No Effort: These diets are particularly attractive to the public because of their claims that weight reduction can take place without effort or change of eating habits. The promoters of such approaches suggest that their products cause the food and associated calories to pass through the gastrointestinal tract without being taken up into the body. These claims, without exception, have been found to be fraudulent.
Semistarvation: These diets are almost like fasting. The dieter eats special low calorie formulations mixed with milk or water. Weight loss is rapid but malnutrition and damage to lean tissues such as muscles, heart, and kidneys are likely if the fast is continued for an extended period of time.
Those who rely on such fad diets for weight control usually find themselves victims of the yo-yo syndrome of alternating weight gains and losses. Although the effects of these up and down weight cycles are unknown, some experts believe yo-yo dieting is very unhealthy and actually might make subsequent weight loss more difficult and weight regain faster. It is likely better not to diet at all than to use a yo-yo approach to weight loss.
Because of individual variation in activity and nutritional requirements, the most effective diet is one that is individualized and based on personal needs and lifestyle. High levels of motivation and persistence are essential if any dieting is to be productive and permanent.
INCREASING ACTIVITY
Another approach to weight reduction is to increase the daily caloric consumption of the body by increasing the level of physical activity through exercise; however, exercise should be paired with dieting because without it exercise is a very slow weight-reduction technique. Not only does exercise increase the utilization of calories, it also decreases appetite, which assists in the dieting effort.
ADMINISTERING DRUGS
Attitudes about the use of drugs as part of a weight-reduction strategy have been changing recently. Although the role of pharmacology in the treatment of obesity continues to be debated, new compounds may be approved by the FDA in the next few years which may dramatically improve the success of therapy for obese patients. There appears to be three principal ways whereby drugs can contribute to the weight-reduction process:
First, medications can be employed which suppress the appetite. These agents are called anorexiants and include all of the currently FDA-approved drugs used to treat obesity. These agents will be discussed in greater detail below. The intent of such medications is to remove the drive to eat which leads to reduced caloric intake and the loss of fat and associated weight. In general, these diet aids are intended for only "temporary use" during a few months, until the patient is able to establish the "dieting habit." Because of potential side effects, the long-term use of these drugs is usually discouraged; however, some clinicians are encouraging patients to continue treatment with these drugs for years or even for a lifetime. The basis for such radical recommendations is that in the vast majority of cases, when use of the anorexiant is stopped, the obese conditions rapidly return and often are even worse than prior to treatment; consequently, some clinicians believe that the health risks associated with the rebound obesity exceed those of using these drugs indefinitely. This controversy is not likely to be resolved in the near future.
Second, weight-reduction drugs may be developed to increase the metabolic rate. By enhancing metabolism, the conversion of fat into calories or energy occurs at a higher level, eliminating the fat stores. Although some currently available OTC diet aid drugs may have this effect to a limited degree, their effectiveness in treating major obesity is suspect. Other drugs which are much more effective in their ability to stimulate metabolism are currently being developed. While this approach has appeal because it suggests pharmacology can be used to burn away unwanted pounds, the potential side effects of such a strategy are unknown.
Third, drugs which alter digestion and thereby reduce the absorption of fats or carbohydrates from the intestines would decrease caloric intake but allow the obese patient to maintain a relatively normal eating pattern. An example of this strategy is the drug, Orlistat. Its use prevents absorption of up to 36% of the fat in the diet. Studies have shown use of Orlistat causes a 10% weight reduction. However, side effects are troubling and include upset stomach, gas and diarrhea. The incidence of problems correlate with fat content: the annoying side effects are diminished by reducing food intake. Another problem with the Orlistat approach is a loss of fat-soluble vitamins (A,D, and K) in the stools.
PRESCRIPTION DRUGS
Prescription drugs currently on the market are approved for relatively short-term use--no more than 12 weeks. While recent studies suggest that obese people using a combination of prescription diet aid drugs lost on average 30 pounds (compared to 10 pounds for those on placebos). The longer-term results were much less encouraging: by 4 years almost all participants (drug- and placebo-treated) had regained their lost weight. The most effective diet aid agents include the amphetamine-like drugs. These prescription drugs possess the following properties:
These agents have limited value, and at best are only useful for short-term use in the treatment of obesity.
Some of the amphetamines possess potential for serious side effects, such as high abuse liability, dependence, irritability, insomnia, high blood pressure, and rapid heartbeat.
When used excessively the amphetamines can affect an individual's behavior, inducing a amphetamine psychosis that resembles paranoid schizophrenia.
Because of the serious nature of side effects associated with the amphetamine-like diet aids, drug inserts for these products contain a warning to prescribers against their use except in patients for whom alternative therapy has been ineffective. Many physicians recommend that these stimulants not be used at all as part of a dieting program. These experts question whether the benefit to dieting associated with amphetamine use justifies exposing a patient to these potent drugs.
Another diet drug which is structurally related to the amphetamines is called fenfluramine (Pondimin) or the related compound dexfenfluramine (Redux). Although chemically related to the amphetamines, fenfluramine tends to have more CNS depressant action, suggesting a distinct mechanism of action. In 1996 and 1997, fenfluramine was frequently prescribed with another diet aid drug, phentermine, in a combination commonly referred to as fen-phen. Although this combination was never FDA-sanctioned, researchers claimed the combination allowed for few side effects (by reducing the dose of each ingredient) while not compromising efficacy. Reports that this drug combination could be continuously used safely for years prompted the fen-phen craze leading to over 18 million prescriptions in 1996 alone. Despite the wide acceptance of this drug combination by clinician and patient alike, the manufacturer (Wyeth-Ayerst) withdrew fenfluramine and dexfenfluramine in September, 1997. The reason for the removal of these drugs was the mounting evidence that continual use of fenfluramine could cause serious, and sometime fatal, valvular heart problems. The fact that as many as 30% of the long-term users of fenfluramine may have coronary damage due to this drug, suggests that there will be considerable malpractice litigation concerning the used of these drugs for the next several years.
Another group of drugs suggested as possible weight-reduction drugs are the antidepressants. Medications such as Prozac are know to suppress appetite in some patients. Although the manufacturers of Prozac considered developing their drug as an appetite suppressant, the fact that tolerance appears to develop to this effect after a month, and a concern about the prospective legal problems developing over the fen-phen incidence, the company decided not to pursue this option. However, the FDA recently approved another weight reduction drug with a Prozac-like mechanism called Meridia (sibutramine). Studies suggest that Meridia is not as effective as the amphetamines (it may help a user to lose up to 14 lbs in a 12 month period) it appears to have fewer side effects. Only time, and experience, will determine if this new drug will survive in the extremely volatile diet aid market.
NONPRESCRIPTION DIET AIDS
The OTC diet aid preparations are substantially less effective than the prescription diet aids and, at best, significantly suppress appetite in only about 30% of the population. Many health professionals view these products as ineffective and unsafe. While the FDA claims OTC diet aids can temporarily enhance weight loss in the moderately obese, they have suggested that the following statement be included on the label of these products:
This statement reflects the agency's concern that past promotions of some weight control drug products have been misunderstood by potential consumers to mean that weight loss results directly from the use of the drug product, and, therefore, it is unnecessary to diet in order to lose weight.
OTC diet aid compounds include the following drug categories:
Some diet products that contain benzocaine are packaged as capsules or tablets and are designed to be swallowed intact. The local anesthetic is not released until the diet aid reaches the stomach and, consequently, has no effect on taste. Some claims have been made that benzocaine, once it gets to the stomach, can cause numbness of the gastric lining and help eliminate the sense of hunger, but whether this assists in weight control is questionable. Even though the FDA advisory panel has acknowledged that benzocaine might be effective for short-term control, others question its value as an adjunct to dieting.
Anorexiants: Prior to November, 2000, the principal example of an OTC anorexiant was the drug phenylpropanolamine. This agent is also classified as a sympathomimetic (Chapter 5) was also commonly employed as a decongestant in cold preparations. While phenylpropanolamine does possess some anorexiant properties, it is less effective than the amphetamines and tolerance to its appetite suppression action develops much more quickly (for most people, in a matter of a few days). Higher doses of this drug are more likely to have a significant anorexiant effect, but are also more likely to cause side effects (especially an increase in blood pressure and heart rate). Regardless of any therapeutic benefit of the agent, the FDA has taken steps to remove phenylpropanolamine from the market because it increases the risk of hemorrhagic stroke in individuals receiving the drug (see Chapter 4).
Herbal Diet Aids: Herbal products are being sold as safe and natural alternative for losing weight. Sometimes there are claims that these herbal products are drug free despite the fact they may contain several ingredients which are pharmacologically active. For example, some herbal diet products contain either laxatives or diuretics: clearly weight loss caused by using such ingredients has no influence on fat storage or problems associated with obesity. If these drugs reduce weight, it is only due to a temporary increase in urination or bowel movement.
Another active ingredient found in herbal diet aids is the drug ephedrine, usually associated with the ephedra plant or Ma Huang (see Chapter 22). Although its appetite suppressing effects have not been determined, ephedrine is likely similar to phenylpropanolamine in its effectiveness. Ephedrine can cause serious cardiovascular problems and its use has been restricted, even in herbal products. Ephedrine should not be used with other stimulants such as caffeine.
Artificial Sweeteners (saccharin & aspartame): Saccharin contains no calories and if used on a regular basis, may allow for a significant reduction in the use of sucrose (table sugar) and its associated calories. Aspartame contains the same calorie levels as table sugar, but is 180 times sweeter and, thus, much less is required. Many people prefer aspartame over saccharin because it has a less bitter after-taste.
Unfortunately, both of these artificial sweeteners have been linked to serious side effects such as bladder cancer (saccharin) and brain damage (aspartame). In fact, the FDA has required warnings to be placed on the labels of products containing saccharin, but not aspartame. However, studies suggest that the potential dangers from normal use of these compounds is small. Both are currently available in food and drinks or in OTC sweetener products.
Other commonly used sucrose substitutes include fructose, sorbitol, mannitol, and xylitol. These compounds can be found in assorted candies, gum and foods. However, these substitutes do contain significant calories, although they are somewhat sweeter than sucrose. In addition, these nonsucrose sugars often adversely affect the gastrointestinal tract and cause gas and cramps.
Fat Substitutes: Following in the footsteps of the artificial sweeteners, fat substitutes have been manufactured and are currently being marketed for weight-conscious consumers. The manufacturer of NutraSweet is merchandising a product called Simplesse which is made of protein derived from milk and egg whites. The protein in these fat substitutes is heated and whipped into microscopic globules that are tasteless but mimic the texture of fat on the taste buds. Simplesse contains about 15% of the calories of real fat and is without cholesterol. Simplesse can be used in foods such as salad dressings, mayonnaise, yogurt, butter and cheese products; however, the globules break down when exposed to intense heat and are not useful in frying or baking. Another fat substitute, Oatrim looks and tastes like fat, but is not absorbed into the body from the gut; because it is heat-resistant it can be used for cooking.
Olestra (Olean): Olestra is a nonabsorbable, energy-free fat substitute recently approved for use in snack foods. Olestra is used as a substitute for regular cooking oil to fry salted snacks, like potato chips. Olestra is made from soybean or cottonseed oil, but processed so that it will not break down and be absorbed from the G.I. track, even though it tastes and feels like ordinary fat. Olestra adds no calories to food. Its use can cause problems for some users. Reports that 10-15% of the users may suffer G.I. discomforts such as cramps, gas and diarrhea, suggest that Olestra should be used in moderation. Another concern is that excessive use of Olestra may interfere with the absorption of the fat-soluble vitamins, A,D,E,K.
SUMMARY
The best treatment for obesity is prevention. This means that concern with weight control should begin early enough in life that the risk of becoming obese is reduced. However, because almost one-third of the population in the U.S. is obese, weight reduction is big business in this country. The American people will continue to be constantly bombarded with propaganda about new, dramatic, and effortless ways to shed unwanted pounds. However, almost without exception, these claims are unsupported by scientific facts and the techniques are completely ineffective in eliminating fat excess. Remember -- there is no easy way to lose weight! Effective dieting requires self-control, commitment, time, and effort. Consequently, permanent weight loss is achieved by a relatively small minority of obese patients; in most cases, weight loss is maintained for only a few months at a time, if at all. Programs incorporating behavioral modification, as it relates to eating habits and exercise, lead to more effective and beneficial long-term weight reduction. But even these well-structured and controlled programs have a poor success rate for longer than 5 years. Finally, until better drugs are developed, diet aid should not be relied on as the primary means for weight reduction; at most, diet aid compounds are only temporary adjuncts intended to assist in establishing the dieting habit.