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Obesity and Being Overweight

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Measurement of 

What Causes   

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Obesity and Being Overweight

An up-to-date article that describes the current thinking on obesity and weight control, including dietary and behavioral dieting methods, plus a look at the new drugs that have replaced Phen-Fen in the medical armamentarium. 

What Is Obesity?

When a person's caloric intake exceeds his or her energy expenditure, the body stores the extra calories in the fat cells present in adipose tissue. These adipose cells function as energy reservoirs, and they enlarge or contract depending on how people use this energy. If people do not balance energy input and output by adopting healthy eating habits and regular exercise, then fat builds up, and they may become overweight.

Measurement of Obesity

Obesity is determined by measurement of body fat, not merely body weight. People might be over the weight limit for normal standards, but if they are very muscular with low body fat, they are not obese. Others might be normal or underweight, but still have excessive body fat. New federal clinical practice guidelines use three key measures to determine whether or not a person is overweight: body mass index (BMI) (a measure of body fat); waist circumference; and a patient's risk factors for diseases and conditions associated with obesity.

BMI. The current best single gauge for body fat is a measurement called body mass index (BMI). It is derived by multiplying a person's weight in pounds by 703 and then dividing it twice by the height in inches. For example, a woman who weighs 150 pounds and is 68 inches tall would have a BMI of 22.8. The result is graded on a scale to indicate levels of body fat. New federal guidelines define overweight as a BMI of 25 to 29.9 and obesity as a BMI of 30 or greater. These guidelines are very important for people at risk for diabetes, heart disease, or certain cancers. Experts argue, however, over what constitutes dangerous weight at different ages or for healthy people with no such risk factors. (See How Serious is Obesity? and Being Overweight, below).

Waist Circumference. New guidelines note that the extent of abdominal fat is very important in assessing risk of disease. One study suggested that women whose waistlines are over 31.5 inches and men whose waists measure over 37 should watch their weight; circumference of greater than 35 inches in women and 40 inches in men signifies increased risk for heart disease, diabetes, and impaired functioning. Distribution of body fat around the abdomen and hips may be a further indication of risk. The distribution of fat can be evaluated by dividing waist size by hip size. For example, a women with a 30-inch waist and 40-inch hip would have a ratio of.75; one with a 41-inch waist and 39-inch hips would have a ratio of 1.05. The lower the ratio the better. The risk of heart disease rises sharply for women with ratios above 0.8 and for men with ratios above 1.0.

Anthropometry. Anthropometry is the measurement of skin fold thickness in different areas, particularly around the triceps, shoulder blades, and hips. This measurement is useful in determining whether weight is due to muscle or fat.

What Causes Obesity?

Cultural Influences on Eating and Activity Patterns
Enough food is produced in the U.S. to supply 3,700 calories every day to each man, woman, and child -- far more than any single person needs to sustain life. Social and cultural pressures certainly play the major role in the current epidemic. In spite of the proven health risks of obesity, the government, insurance companies, and the medical profession spend very little money to oppose the billions of dollars that the food industry spends to promote food products. Studies are implicating soda and fruit juice as major contributors to childhood obesity. (Juice, while better than soda, is still filled with sugar and contains little else of nutritional value.) Children are particularly vulnerable to the temptations proffered by the media, and the culture and educational system provide few attractive, healthy alternatives.

Both leisure and working time are increasingly sedentary as people move from one seated position to another in their use of the automobile, the television, video games, and the computer. The effect of the Western culture can be demonstrated by the fact that adolescent obesity increases dramatically among second- and third-generation immigrants to the US as they adopt the American diet and lifestyle. In spite of a recent study that indicated that a school-based educational program can reduce obesity, many public schools still have no physical education programs, and, in 1995, the government allotted only $50,000 for each state's nutritional education budget. One study has found that the annual distance walked by children has fallen by nearly 30% since 1972, partially because more parents are driving their children to school out of fear of abduction, molestation, and traffic accidents. Excessive television watching, however, plays a critical role in obesity in children, particularly in girls and minority children. According to another study, many girls enter a period of reduced physical activity in the two to three years leading up to puberty, which appears to be a particularly crucial period in determining the development of continuing obesity. (It should be pointed out that the extreme reactions to overeating -- severe dieting in children and low-fat diets in infants -- are also dangerous.)

Metabolic and Behavioral Regulation by the Brain
Weight is determined by pathways that occur in both the brain and gastrointestinal tract. Eating patterns are regulated by feeding and satiety centers located in the hypothalamus and pituitary glands of the brain that respond to signals indicating high fat stores and hunger. Substances critical in this process include glucose (sugar), insulin (a hormone that is critical in the conversion of blood sugar, or glucose, into energy), and leptin (an enzyme that signals the brain when fat stores are high).

Leptin has many functions that are of great interest in the study of obesity and, perhaps, diabetes. This hormone is released by fat cells; levels rise as more fat is stored in the cells. Rising levels appear to signal the hypothalamus to suppress appetite and falling levels to stimulate appetite. (In one study, a genetic mutation was associated with early-onset obesity and leptin deficiency.) Leptin may also affect the body's resistance to the effects of insulin, a hormone that is critical for metabolizing blood sugar. A recent animal study has shown that leptin is secreted not only by fat cells but also by cells in the stomach. Cholecystokinin, a hormone in the upper intestine that stimulates digestive juices, may work with leptin to stimulate or suppress appetite. The mechanisms by which leptin contributes to obesity, however, are still unclear.

The level of the body's stores of fat may also be dictated by a mechanism in the brain, commonly called the adipostat, that seeks to maintain a preconceived body weight. The adipostat establishes a set point for a fixed amount of body fat just as a thermostat regulates heat according to a preset temperature. The brain maintains this pre-established goal by subtly regulating the expenditure or storage of energy until fat stores meet the level determined by the adipostat. Unfortunately, in the case of obesity, the adipostat may set its goal at an unhealthy level, perhaps having used as its basis high fat levels in childhood or weight gained slowly and steadily during adulthood. Losing weight in such cases becomes extremely difficult because, unknown to the person who has been painfully dieting, the brain is busily undermining these efforts by working to restore the original weight. It may do this by activating the sensation of hunger so that more calories are consumed, by slowing the metabolism, or by subtly reducing exercise efforts so that fewer calories are burned. The adipostat can be reset for lower fat stores only over a long period of consistently healthy eating and regular, vigorous exercise.

Genetic Factors
Genetic factors influence fat metabolism and regulate certain hormones and proteins that affect appetite and may play some part in 70% of obesity cases. A number of genetic variations, however, are involved in making people susceptible to obesity. Inherited attributes can include the way fat is distributed, metabolic rates, changes in energy responses to over eating, food preferences, and other factors. Genetic factors may also play a direct role in some cases of very severe obesity. Although genetic abnormalities may make it harder or easier to lose weight, however, the prevalence of obesity has dramatically increased over the past two decades, and genes cannot have changed within that time. The human metabolism evolved so that it could conserve energy and store fat during times of famine. Most cases of obesity occur now in people with normal physiology who live in industrialized nations where food is overly plentiful, and it is easy to avoid expending enough energy to burn the excess calories.

One theory suggests that type 2 diabetes and the obesity that usually accompanies this disorder are derived from genetic actions that were once important for survival. Some experts postulate the existence of a so-called "thrifty" gene, which regulates hormonal fluctuations to accommodate seasonal changes. In certain nomadic populations, hormones are released during seasons when food supplies have traditionally been low, which results in resistance to insulin and efficient fat storage. The process is reversed in seasons when food is readily available. Because modern industrialization has made high-carbohydrate and fatty foods available all year long, the gene no longer serves a useful function and is now harmful, because fat, originally stored for famine situations, is not used up. Such a theory could explain the high incidence of type 2 diabetes and obesity found in Pima tribes and other Native American tribes with nomadic histories and Western dietary habits. The traditional low-fat high-fiber foods (corn, lima beans, white and yellow teparies, mesquite, and acorns) of the Pima people may have protected this genetically susceptible population in the past from the high incidence of obesity and Type 2 diabetes they are experiencing now. Some genetic mutations that have recently been associated with specific cases of obesity include one that appears to increase the number and size of fat cells and is associated with massive obesity. Another is a gene called melanocortin-4 receptor that plays a key role in shutting off the urge to eat and which is defective in some families with a history of obesity. Researchers have also identified a mutation in a gene for a protein called POMC, which affects several different hormones and results in a syndrome of obesity, red hair, and deficiencies in stress hormones.

Other Causes of Obesity
A number of medical conditions may contribute to being overweight, although rarely are they a primary cause of obesity. Some overweight people may believe their weight problem is due to hypothyroidism; patients with an underactive thyroid, however, generally show only a moderate weight increase of five to 10 pounds, mainly due to accumulation of fluid. Cushing's disease is a rare condition caused by high levels of steroid hormones, which results in obesity, a moon-shaped face, and muscle wasting. Obesity is also linked with polycystic ovarian syndrome and very rare disorders, including Froehlich's syndrome in boys, Laurence-Moon-Biedl, and the Prader-Willi syndromes. Of interest was one small study that found evidence of a previous infection by an organism called an adenovirus Ad-36 in obese -- but not lean -- people. More research is needed.

Who Becomes Obese or Overweight?

Obesity in Adults
Everyone who has a sedentary lifestyle with unhealthy eating habits is at risk for obesity. A sedentary lifestyle and obesity play against each other in a no-win game. Lack of exercise contributes to weight gain, and obesity makes it difficult to exercise vigorously. The World Health Organization now considers obesity to be a global epidemic and a public health problem as more nations become "Westernized". In spite of a recent survey that 73% of Americans consider themselves to have either an ideal or a healthy weight, new federal guidelines estimate that 55% of the American adults, or 97 million, are either overweight or obese. If the trend persists, the entire US adult population could be overweight within a few generations. It should be noted, however, that although obesity (over 30 BMI) is certainly dangerous, there is considerable doubt that simply being overweight (between a BMI of 25 and 28) poses significant dangers for people who are otherwise healthy and have no risk factors for diabetes, heart disease, or cancer.

In men, BMI tends to increase until age 50 and then it levels off; in women, weight tends to increase until age 70 before it plateaus. Gaining some weight is inevitable with age and adding about 10 pounds to a normal base weight over time is not harmful. However, in one study, 64% of women and 73% of men between ages 50 and 60 were seriously overweight. The tendency in the U.S. is toward an unhealthy average increase of one pound per year after age 25. This condition is made worse by the fact that muscle and bone mass decrease with age, so the fat increase is actually about one and a half pounds. This means that by age 55, the average American has added over 37 pounds of fat during the course of adulthood.

Obesity in Children
More children and adolescents are overweight in America than ever before, with about 12% of children and 10% of adolescents suffering from this condition.

Fat cells multiply during two growth periods: early childhood and adolescence; overeating during those times increases the number of fat cells. Genetics also determine the number of fat cells a person has, and some people are simply born with more. Parental influence certainly plays a role; when a parent of a child under three is obese, the child -- even if thin -- has a 30% chance of becoming obese later on. As children get older, however, obesity in their parents starts to count less as a predictor for weight in later life than obesity in the children themselves. The likelihood that a child will become obese gradually increases as a child matures. For example, although one study suggested that the weight of a toddler does not appear to influence the risk for obesity, an overweight 15-year old is 17 times more likely to be overweight as an adult than a normal-weight adolescent. After adolescence, fat cells tend to increase in mass rather than quantity, so that adults who overeat and gain weight tend to do so because they have larger fat cells, not more of them. Losing weight in adulthood reduces the size of the fat cells but not their number, so weight loss becomes much more difficult for adults who were overweight as children when fat cells were replicating.

Specific Groups at Risk
Ex-Smokers. The trend toward weight increase has followed the trend for quitting smoking. Nicotine increases the metabolic rate, and quitting, even without eating more, can cause a weight gain, which may be considerable. It is important to note that weight control is not a valid reason to smoke. People in previous centuries did not smoke cigarettes, nor were they usually obese.

Shift-Workers. A recent study found that individuals who work late shifts (between 4PM and 8AM) tend to eat more and take longer naps than day workers and are more likely to gain excess weight.

How Serious Is Obesity and Being Overweight?

General Outlook for the Person Who Is Overweight
In general, studies indicated that the lowest risks for heart disease, diabetes, and some cancers are in people with body mass index (BMI) values of 21 to 25. The risks increase slightly when BMI values are between 25 and 27; they are significant in BMIs between 27 and 30 and are dramatic over 30. (For calculating the BMI, see What Is Obesity?, above.) Anyone with risk factors for health problems must be concerned about extra weight. Experts are still debating, however, about the degree to which overweight hurts healthy people with no risk factors for serious illnesses. Some argue, in fact, that in anyone who is not severely obese, it is not the weight per se but the accompanying unhealthy diet and sedentary lifestyle that causes harm. Age may play a role in helping to define the risk from obesity. In one study, the younger the adult, the more dangerous the weight gain -- particularly in men. For example, an incremental gain of 1 BMI value increased the risk for death from heart disease by 10% in men 30 to 44 years old but only 3% for men over 65. For women in the same age groups, the increased risks were 8% and 2%, respectively. (It should be noted that the absolute risk for death from heart disease and cancer is very low in all young adults and an increased risk still means that only a very few additional people will die from these diseases.) The same study suggested that for healthy nonsmoking men over age 75 and for women over 65 being overweight has little effect on mortality, and, in fact, may be protective, particularly in older women. Other studies have also suggested that elderly people who are very thin have an increased risk of death compared to heavier people. Excess fat in older people may provide a nutritional reserve and insulate bones from fall-related injuries. (These studies may also simply indicate that heavy people who manage to live into old age may be immune to the adverse effects of obesity.) Everyone should take very seriously studies indicating that obese children often have a life-long struggle with their weight and are at high risk for developing high blood pressure, diseased arteries, damaged hearts, and liver damage in adulthood. Parents should be advised, however, to approach any weight program for their children by encouraging healthy diets and exercise. They should not express criticism of their children for being overweight. Such attitudes could put children at risk for eating disorders -- equal or even greater dangers to health.

Cardiovascular Disease and Diabetes
Obesity is a risk factor for heart disease, high blood pressure, diabetes, and stroke. One study reported that obesity in childhood, is a stronger predictor of heart disease than is a family history of heart problems. Weight concentrated around the abdomen and in the upper part of the body poses a higher health risk than fat that settles in a pear-shape around the hips and flank. Fat cells in the upper part of the body appear to have different qualities from those found in the lower parts.

High Blood Pressure. Obesity is a major risk factor for hypertension. Even worse, overweight people with high blood pressure are at increased danger for enlargement of the left heart chamber, a major risk factor for heart failure. Obesity may cause high blood pressure over time by altering the kidney's physical characteristics and function, leading to retention of sodium and water. Blood pressure rises as the body tries to restore the flow of fluids. Even modest weight loss is beneficial for reducing blood pressure and the risk for heart failure.

Cholesterol Levels. The effect of obesity on cholesterol levels is complex but not advantageous; total cholesterol and triglyceride levels are usually high while HDL (the "good" cholesterol) levels are low.

Insulin Resistance and Diabetes Type 2. Obesity is strongly associated with type 2 diabetes (previously called non-insulin dependent or adult-onset diabetes). Almost 90% of type 2 diabetics are obese. Although only a minority of obese people is diabetic, researchers have blamed obesity and sedentary living for the dramatic increase in type 2 diabetes over the past years. Type 2 diabetics generally have normal or high levels of insulin, a critical hormone in the metabolism of sugar. However, they are unable to use the insulin, a condition called insulin resistance, which is now thought by many experts to be an independent risk factor for heart disease. According to one study, insulin resistance itself is caused by increased body fat. The key to the association may be leptin, which is produced by fat cells; high levels have been found to coincide with insulin resistance.

Excess weight may be a strong risk factor for esophageal cancer, particularly in young nonsmokers. The increased risk may be due to a higher incidence of gastroesophageal reflux disorder (heartburn) in people who are overweight. (Obesity does not appear to be related to a higher risk for stomach cancer.) Women who are obese appear to have two to three times the risk for uterine cancer as thinner women. Obese women are also at higher risk for gallbladder cancer, and obese men are at higher risk for colon and prostate cancers. Studies have reported mixed effects on the association between obesity and breast cancer. A number of studies have linked obesity to breast cancer in postmenopausal women. Studies are finding that simply being overweight is not a risk factor but that women who gain weight after age 18 and who never take estrogen face a higher risk for developing breast cancer after menopause. One also suggested that being heavier as a child conferred a lower risk for breast cancer after menopause.

Muscles and Bones
Obesity places stress on bones and muscles, and overweight people are at higher risk for hernias, low back pain, and aggravation of arthritic conditions. In one study, obese workers were over three times more likely than slender people to develop carpal tunnel syndrome and other problems involving nerves in their wrists and hands.

Gum Disease
People who are obese are at an increased risk for gum disease.

The incidence of gallstones is higher in obese women and men. The risk for stone formation is also particularly high if a person loses weight too quickly. In people on ultra-low calorie diets, gallstones may be prevented by taking ursodeoxycholic acid (Actigall).

Reproductive and Hormonal Problems
Women who gain weight after age 18 are at higher risk for developing uterine fibroids. Abnormal amounts of body fat, either 10% to 15% too high or too low, can contribute to infertility in women. In men, obesity can contribute to reduced testosterone levels. The dangerous effects of obesity on pregnancy are multifold. They include high blood pressure, gestational diabetes (diabetes, usually temporary, that occurs during pregnancy), urinary tract infections, blood clots, prolonged labor, a higher fetal mortality rate in late stages of pregnancy, and Cesareans. Infants of women who are obese are also at higher risk for neural tube birth defects, which affect the brain or spine. Folic acid supplements, ordinarily effective in preventing these conditions, may not be as protective in overweight women.

Obesity puts people at risk for hypoxia, in which oxygen is insufficient to meet the body's needs. Obese people need to work harder to breathe and tend to have inefficient respiratory muscles and diminished lung capacity. The Pickwickian syndrome, named for an overweight character in a Dickens novel, occurs in severe obesity when lack of oxygen produces profound and chronic sleepiness and, eventually, heart failure.

Sleep Apnea and Sleep Disorders
People who are obese and nap tend to fall asleep faster and sleep longer during the day; at night, however, it takes them longer to fall asleep and they sleep less than people with normal weights. In an apparent viscous circle, studies have suggested that not only can obesity interfere with sleep, but that sleep problems may actually contribute to obesity. Obesity is particularly associated with sleep apnea, which occurs when the upper throat relaxes and collapses at intervals during sleep, thereby temporarily blocking the passage of air. Some people may not even know they have this condition except for vague symptoms, such as morning headache, fatigue, and irritability. Sleep apnea is associated with a higher risk of heart arrhythmias, stroke, right-sided heart failure, and car and other accidents due to daytime drowsiness. Sleep apnea may actually contribute to weight gain by depriving people of REM (rapid eye movement) sleep. This is the dreaming phase of sleep, necessary for long-term emotional well being; REM deprivation has been linked to overeating. In any case, sleep deprivation, with or without sleep apnea, can leave people feeling tired and more vulnerable to snacking and less likely to exercise.

Binge-Eating and Other Eating Disorders
About 30% of people who are obese are binge-eaters, who typically consume 5,000 to 15,000 calories in one setting. To be diagnosed as a binge eater, a person has to binge at least twice a week for six months. Many experts believe that binge-eating carbohydrates causes an increase in natural opiates leading to dependence on carbohydrates, and, therefore, the condition should be treated as addiction. Dangerous consequences of binge eating are its antitheses -- the eating disorders bulimia and anorexia. Bulimia is binge-eating followed by purging in order to lose weight. Anorexia is severe weight loss. Both conditions pose risks for serious medical problems, and anorexia can be life threatening.

Emotional and Social Problems
A study that followed obese adolescents for seven years found that, compared to thinner peers, overweight women completed fewer years of school, were 20% less likely to be married, and had 10% higher rates of household poverty. Overweight men were not as severely affected as women, although 11% were less likely to be married than nonobese men and their incomes were lower. Sick days, healthcare costs, and short-term disability all rise with increasing BMI values in workers. No evidence exists, however, that obese people suffer from emotional disorders, such as major depression or anxiety, to any greater degree than thinner people. Generally, depression and anxiety are caused by the weight problem and are usually resolved by weight loss.

What Are the General Guidelines for Weight Treatments?
Between 15% to 35% of Americans spend up to $50 billion trying to lose weight 
each year. Because of the high failure rate of most dieting programs and growing evidence that overweight people are fighting a biologic mechanism that works against conscious efforts to control weight, a number of groups are working to change social perspectives and advocate acceptance of high weight levels as a natural state. Certainly, the current cultural bias toward extreme thinness in women has caused an unwholesome and distorted view of what human body shape should be and has created an ideal that almost no one can or should achieve. Obesity, however, is anorexia's alter ego and is epidemic now because of the over-availability of food and the low demands made on the metabolism by our sedentary culture. Extreme levels of weight -- either too high or too low -- are unhealthy and not usually a natural condition. Weight loss is, indeed, so difficult to battle alone against a constant barrage of advertising, discrimination, and the insidious opposition of the body itself, that no one should be faulted or socially ostracized for failing or for giving up the effort altogether. On the other hand, obesity still poses a threat to life, health, and well being, and the struggle against it is worthwhile. Even moderate weight loss and a modest exercise program helps improve survival and quality of life. It is crucial that no one should accept obesity in children, unless there is a proven and unretractable medical reason.

According to a recent study, exercise, problem-solving skills and social support are the most important predictors of success in a weight-loss program. Weight loss however should not be the only or even the primary goal for people concerned about their health. Some experts believe that it is not weight that causes the diseases associated with being overweight but the accompanying unhealthy foods and sedentary lifestyles. They point to one study, in which obese people began exercising regularly and consumed a diet rich in fruits, vegetables, and whole grains and low in fats. After only three weeks, indicators for heart disease (cholesterol and triglyceride levels, blood pressure, and insulin) had all improved although the average weight loss was less than five percent. Other studies have also found health gains with only a 5% to 10% reduction in weight. Unfortunately, physicians, who generally have limited time as well as training in nutrition and weight management, may be tempted to prescribe diet pills -- particularly when urged by the patient -- when a long-term program of diet and exercise is more appropriate. Some experts even recommend that physicians should work only as care-coordinators, with nurses or dietitians providing the hands-on treatment.

What Are the Diets and Lifestyle Methods for Managing Weight?

Although many studies report low long-term success rates for people who lose weight, it should be noted that most of these studies are conducted with very obese subjects who are enrolled in severe weight reduction programs. Everyone should be warned, however, that diet failure is extremely common. To make the dieting process even more difficult, an obese person often cannot use hunger pangs as a natural signal to eat. A stomach that has been stretched by large meals will continue to signal hunger for large amounts of food until its size reduces over time with smaller meals. Even repeated weight loss failure is no reason to give up. Much concern has been raised about the long-term adverse effects of yo-yo dieting, or weight cycling. Studies indicate, however, that such cycles have no adverse psychological or physical effects. Furthermore, studies have reported that even after repeatedly losing and regaining weight, people do not lose their ability to burn calories efficiently. The most important key to success is to approach the changes in diet and exercise not as punishment but to plan and implement pleasurable healthy substitutes for compulsive overeating and sedentary behavior.

Low-Fat and Sugar and High-Fiber Diets
Some studies suggest that replacing foods high in fats and sugars with low-fat complex carbohydrates (fruits, vegetables, and whole grains) may be more effective than calorie counting, particularly in maintaining weight loss. Counting only grams of fat, in fact, may be more effective than keeping a record of daily food intake. One gram of fat contains 9 calories while one gram of carbohydrates or protein has only 4 calories, and dietary fat converts more readily to fat in the body than carbohydrates or proteins. In a one-year study, those on low-fat diets lost three times as much weight as those on a standard low-calorie diets. Many people, however, who reduce their fat intake do not consume enough of the basic nutrients, including vitamins A and E, folic acid, calcium, iron and zinc, and they often increase their intake of carbohydrates. No one should use a low-fat diet as an excuse for over-consuming carbohydrates, particularly starchy foods and sugar. A high calorie diet from any source will add pounds. People on low fat diets should consume a wide variety of foods and take a multivitamin if appropriate. Simply switching to low-fat or skimmed milk may help people achieve the recommended dietary goal of 30% or fewer calories from fat and also help provide calcium. Some fat in a diet is essential. It should be derived from non-tropical plant oils and fish. Saturated fat from animal products and trans-fatty acids from hydrogenated (hardened) oils should be avoided.

Fat Substitutes. Fat substitutes added to commercial foods or used in baking deliver some of the same desirable qualities of fat but do not add as many calories. Some replacers, such as the cellulose gel Avicel, Carrageenan (made from seaweed) guar gum, and gum arabic have been used for decades in many commercial foods and are generally recognized as safe. A recent synthetic fat, olestra, passes from the body without leaving behind any calories from fat. (It should be noted that foods containing this substance still have some calories from carbohydrates and proteins.) There have been reports of cramps and mild to severe diarrhea after eating food containing olestra, although a recent study found that when people ate chips containing olestra in one sitting they experienced no more symptoms than those eating chips containing fats.. Olestra, however, depletes the body of vitamins A, K, D, and E and important disease-fighting nutrients found in dark colored fruits and vegetables. The FDA requires that the missing vitamins be added back to olestra products, but not replacement of other important nutrients, such as carotenoids, that are being depleted. Nutrition experts are concerned about the dramatic drop in blood levels of these nutrients, which may increase the risk of cancer, stroke, and heart disease. Furthermore, a survey of researchers on an expert committee for diet, nutrition, and cancer, revealed that not a single member would have approved olestra using FDA criteria. Under investigation are fat-substitutes derived from oats (Oat Trim and Z-Trim), which may have some health benefits other than merely reducing calories and replacing hydrogenated or saturated fats.

Fiber. All healthy diets should be high in fiber, which is an important weight loss-factor. It interferes with absorption of fat and protein and, along with the nutrients found in high-fiber foods, may reduce the risk for heart disease, diabetes, digestive disorders, and certain cancers. Fiber is found only in plants. For weight loss, insoluble fiber (found in wheat bran, whole grains, seeds, and fruit and vegetable peels) is most effective. Soluble fiber (found in dried beans, oat bran, barley, apples, citrus fruits, and potatoes), however, has important benefits for the heart. Pectin, a fiber found in apples, citrus fruits, and other fruits and vegetables, has been found to increase and prolong the feeling of fullness after eating in people of normal weight.

Sugar Substitutes. Artificial sweeteners include saccharin, aspartame (Nutra-Sweet), and acesulfame K (Sweet One). A new one, sucralose (Splenda), may also prove to be a good alternative to sugar. It usually leaves no bitter aftertaste and, unlike most other artifical sweeteners, it works well in baking. Dozens of animal studies and some human trials conducted over 15 years have found no health hazards. Early studies found that large amounts of saccharin cause cancer in rats, but these findings do not apply to humans. Aspartame has come under scrutiny because of rare reports of neurologic disorders, including headaches or dizziness, associated with its use. Concern about an association between an increased rate of brain cancer and widespread use of aspartame is unfounded.

Calorie Restrictive Diets
Calorie restriction has been the cornerstone of obesity treatment. The first step is to calculate the daily caloric need for maintaining a healthy weight. This usually calls for 12 to 15 calories for each pound of ideal body weight, but it varies depending on gender, age, and whether a person is active or sedentary. (For instance a 50-year old woman who wants to maintain a weight of 135 pounds and is mildly active might require only 1,650 calories a day, but a 25-year old female athlete who wants to maintain the same weight might require about 2,000 calories a day.) As a rough rule of thumb, one pound of fat equals about 3,500 calories, so one could lose a pound a week by reducing daily caloric intake by about 500 calories. Naturally, the more severe the daily calorie restriction, the faster the weight loss.

Extreme diets of less than 1,100 calories carry health risks and are often followed by bingeing or overeating and a return to the obese state. Such diets usually have insufficient vitamins and minerals, which must then be taken as supplements. Severe dieting has unpleasant side effects (including fatigue, intolerance to cold, hair loss, gallstone formation, and menstrual irregularities) and can be dangerous. Most of the initial weight loss is in fluids and minerals; later, fat is lost, but so is muscle, which can account for more than 30% of the weight loss. It is very dangerous to be on severe diets longer than 16 weeks or to fast for more than two or three days. There have been rare reports of death from heart arrhythmias when liquid formulas did not have sufficient nutrients. Of note, those whose diets include a high intake of fluids and much reduced protein and sodium are at risk for hyponatremia, which can cause fatigue, confusion, dizziness, and in extreme cases, coma.

High Protein Diets
High-protein low-carbohydrate diets have become popular again. Although a high-protein diet will lead to quick weight loss, its health benefits are dubious. One byproduct of this diet is the release of substances called ketones, which can cause nausea, lightheadedness, and bad breath. Such high-protein diets may also be high in fat and low in fiber-rich and healthful whole grains, fresh fruits, and vegetables. Some experts believe that these high-protein diets often result in carbohydrate binges. However, a recent study found that a so-called ketone diet, which is high in protein and very low in fats and carbohydrates can be a safe and effective weight loss regimen for dangerously obese adolescents if they are carefully monitored by a health professional. In the study, the diet not only improved weight loss, but also decreased cholesterol levels and even restored normal sleep patterns in those who had previously suffered from sleep apnea.

Commercial Weight-Loss Programs
This report cannot possibly address the many commercial weight-loss programs currently available or assess their claims. Most of the programs that offer packaged meals and planning guides tend to be very expensive and have not publicized their results. One encouraging study, however, reported that most subjects who had undergone a 12-week weight loss program and then used Ultra Slim Fast supplements as directed for maintenance kept off more than half their weight loss after more than three years. A quarter of the subjects were still losing weight.

It should be noted that the dangers from obesity are not from simply being overweight; they arise from the presence of too much fat. Exercise, which replaces fat with muscle, is the critical companion for any weight control program, but it is as hard to sustain as dieting. Because obesity is so often related to heart and other diseases, anyone who is overweight must discuss their exercise program with a physician before starting. Most experts recommend building up to 45 to 60 minutes a day of mostly aerobic exercise, such as hiking, brisk walking, or energetic dancing. The treadmill burns the most calories. Included in the regimen should be resistance, or strength, training performed two or three times a week, which is excellent for replacing fat with muscles. Such exercise doesn't need to be done at once, but can be spread out over the day. In fact, a new study found that for both exercise adherence and total weight loss, frequent exercise sessions as short as 10 minutes in duration may be the most successful program for obese people. It should also be stressed that any regular exercise has value; even moderate regular exercise helps improve insulin sensitivity (which, in turn, helps prevent heart disease and diabetes.)

Although even vigorous workouts do not immediately burn great numbers of calories, the metabolism remains elevated after exercise, and the more strenuous the exercise, the longer the metabolism continuous to burn calories before returning to its resting level. This state of elevated metabolism, can last for as little as a few minutes after light exercise to as long as several hours after prolonged or heavy exercise. Although the calories lost during the post-exercise period are not high, over time they may count significantly for maintaining a healthy weight. Exercise also improves psychological well being and replaces the sedentary habits that usually lead to snacking. Exercise may even act as a mild appetite suppressant. It is important to realize that as people slim down, their initial level of physical activity becomes easier and they burn fewer calories per mile of walking or jogging. The rate of weight loss slows down, sometimes discouragingly so, after a initial dramatic head start using diet and exercise combinations. People should be aware of this phenomenon and keeping adding to their daily exercise regimen. As people age, they also need to exercise more to keep off the same amount of weight.

Cognitive-Behavioral Therapy
The goal of cognitive-behavioral therapy is to change the daily patterns associated with eating; it is very useful for preventing relapse after initial weight loss. The patient first records in a diary all activity related to eating patterns, including the times of day, length of meal, emotional states, companions, and, of course, the kind and amounts of food eaten. (Patients tend to underreport their dietary intake, but it is still a good method for increasing their awareness of eating patterns.) The therapist and the patient review the diary for setting realistic goals and identifying patterns that the patient can change. For instance, if food is normally eaten while watching television, then the patient may be advised to eat in another room instead. Good eating habits are reinforced by rewards -- other pleasures that substitute for high calorie consumption and sedentary activities. One patient said that recording circumstances surrounding relapses was a particularly valuable guide for understanding the stresses leading to her own eating behaviors. Behavioral modification has been shown to be helpful particularly for people who have an overly strong response to the taste, smell, and appearance of food.

What Are Drugs and Procedures Used to Treat Excess Weight?

Drugs used for weight loss are generally called anorexiants. Most lose their effectiveness over time, thus requiring increased dosage, and they can be addictive and dangerous. None of these drugs deals with the underlying problems that may be causing obesity. Unless specifically instructed by a physician, people should use non-drug methods for losing weight. Except under rare circumstances, pregnant or nursing women should never take diet medications of any sort, including herbal and over-the-counter remedies.

Over-The-Counter Diet and Herbal Remedies
People must be cautious when using any weight-loss medications, including over-the counter diet pills and herbal or so-called natural remedies. Over-the-counter diet pills that contain phenylpropanolamine (Acutrim, Dexatrim) have been known to cause severe high blood pressure and stroke if taken in doses of 75 mg or higher in the immediate-release form. The so-called "herbal fen-phen" remedies (Herbal Phen-Fen, PhenTrim, Phen-Cal) contain ephedrine, derived from the ephedra (also known as Ma Huang) herb. Studies have reported severe effects (rapid heart beat, high blood pressure, psychosis, and seizures) from over-the-counter remedies that contain even small amounts of ephedrine. Eighteen deaths have occurred with its use since 1994, mostly from heart attack and stroke. Dietary supplements, teas, and laxatives that list the ingredient plantain may contain digitalis, a powerful chemical that effects the heart. (This should not be confused with the harmless banana-like plant also called plantain.) Many dietary herbal teas contain laxatives, which can cause gastrointestinal distress, and, if overused, may lead to chronic pain, constipation, and dependency. In rare cases, dehydration and death have occurred. Some laxative substances found in teas include senna, aloe, buckthorn, rhubarb root, cascara, and castor oil. Some fiber supplements containing guar gum have also caused obstruction of the gastrointestinal tract.

Serotonin-Releasing Anorexiants
Some diet pills work by increasing the availability of serotonin, a chemical in the brain that prevents depression and reduces calorie consumption. Unfortunately, the most popular of these drugs have very serious side effects, including development of abnormalities in the valves of the heart and, uncommonly, a potentially life-threatening condition called pulmonary hypertension. As a result, dexfenfluramine (Redux), fenfluramine (Pondimin), and the combination drug commonly called fen-phenfenfluramine (Pondimin) combined with another anti-obesity drug called phentermine -- have been pulled from the market. Phentermine (Ionamin, Adipex, Fastin) is still available. Studies are underway to determine whether these valvular abnormalities will eventually reverse after withdrawal from the drug. Recent ones have reported that the increased risks for valvular problems range from between 2% and 24% in people who took these drugs. The risks are highest in people taking the drugs for long periods or in high doses. Taking the drugs for a short period (two to three months) appears to do no harm. Some experts urge that all patients who were treated with Redux, Pondimin, or phen-fen for more than three months have a thorough cardiovascular exam, including an echocardiogram. Many women who have valvular abnormalities had been taking multiples of the recommended dosages. Others were also on Prozac, an antidepressant that also increases serotonin and intensifies the effects of the diet drugs. It should be noted that taking phentermine (which is still available) along with Prozac or similar drugs known as serotonin reuptake inhibitors or the antidepressants known as monoamine oxidase inhibitors can have similar dangerous effects.

Sibutramine (Meridia) keeps serotonin and norepinephrine, another
neurotransmitter, in balance and increases metabolism. Studies are showing significant weight loss and reduction in factors relating to diabetes. One reported an average drop in weight of 11% in obese patients taking sibutramine for six months. Sibutramine causes a feeling of fullness and increases energy levels. Side effects include dry mouth and insomnia. There have been no reports of pulmonary hypertension with this drug, as there were with phen-fen, but some people taking it reported high blood pressure and some abnormal heart rhythms. Experts believe sibutramine is probably safe, but the long-term effects are stil unknown. People who already have high blood pressure, a history of stroke, or arrythmias should not take this drug. People taking decongestants, bronchodilators (such as for asthma), monoamine oxidase inhibitors, or serotonin reuptake inhibitors should also avoid sibutramine.

Orlistat (Xenical) slows down the production of lipase, an enzyme in the stomach that breaks down fat. It does not increase serotonin but it makes it work effectively, and it is a stimulant. A recent study has found that at the end of the first year orlistat users achieved an average 10% drop in body weight. Furthermore, during the second year patients who continued on orlistat gained back half as much weight as the patients who switched to a dummy pill. (An earlier study reported less impressive weight loss -- about 5% after a year. In the second year, about one third regained their lost weight.) The drug can cause gastrointestinal problems and may interfere with absorption of vitamins A, D, and E. Early concerns of an increased risk for breast cancer have not been confirmed.

The amphetamines dextroamphetamine (Dexedrine), methamphetamine (Desoxyn), and phenmetrazine (Pleudin) were used most often in the past but are no longer prescribed for weight loss. These drugs elevate mood and produce some modest weight loss over the short term, but present serious risks of addiction, agitation, and insomnia. Less addictive and possibly safer derivatives of these drugs include benzphetamine (Didrex), diethylpropion, and phendimetrazine (Adipost, Botril, Melfiat, Plegine, Prelu-2, Statobex), and mazindol (Mazanor, Sanorex).

Experimental Therapies
Naltrexone. The drug naltrexone (Trexan) blocks the euphoria of drug abusers and is being tested for people who binge. Its effects have been promising. (The drug has no effect on people who do not binge.) It is, unfortunately, available only by injection.

Leptin. Preliminary results from an early study examining genetically engineered leptin reported that patients on the highest dose lost 8% of their body weight after six months and the drug was well tolerated. Results from another study showed that the steroid dexamethasone can double the concentration of leptin in the blood, suggesting that it may prove to be an effective drug in the treatment of obesity.

Growth Hormone. In a recent study, treatment with a combination of growth hormone and an insulin-like substance was shown to improve fat loss when added to diet and exercise in postmenopausal obese women. The drug is administered with self-injection and can cause water retention and swelling (edema.)

Phototherapy. Phototherapy uses intense bright light (1,500 lux), which has an effect on melatonin (a powerful hormone that regulates sleep and other functions) and serotonin. It is often beneficial for depression affected by seasonal changes. One small study using phototherapy each morning reported that three out of four women who were sensitive to the effects of light lost between three and five pounds after ten days. This benign treatment is worth researching.

Spot Reduction
Spot Exercising. Anyone seeking to lose weight must expect that the results may not be as cosmetically satisfying as one would wish. Spot exercising -- training particular areas of the body -- is ineffective in reducing fat in specific locations, because exercise draws on fat stores throughout the body. Gimmicky devices such as bust developers, vacuum pants, and exercise belts do absolutely nothing to reduce fat in specific locations or, in the case of the bust developer, to add bulk. Electrical pads wrapped around the waist, arms, or thighs were reported to cause burns and fires.

Cellulite-Removal Cream. Many women try to reduce fat in their thighs (cellulite) with creams that contain aminophylline (Cellution, Skinny Dip, Thermojetics Body Toning Cream, Smooth Contours). One study found no reduction of either thighs or stomach areas in women who used the cream for eight weeks. Studies provide no evidence that these creams are effective. Their apparent effect on fat may simply be from constricting blood vessels and forcing water from the skin, which could be dangerous for people with circulation problems.

Liposuction. Liposuction does get rid of fat cells in specific areas, such as the thighs, buttocks, or knees, and weight gain generally occurs more in other locations after the operation. The pain after the operation can be severe and often the skin does not contract, resulting in a flabby look. Ultrasound liposuction is being tested, which uses a thin wand that vibrates fatty tissue at high speed until it breaks down and liquefies. Fat is then removed with pressure suction. The procedure may be able to remove large volumes of fat, including fat in areas ordinarily hard to reach using standard liposuction techniques. Complications include burns from the vibrators.

Surgical procedures may be appropriate for some dangerously obese people Experts recommend surgery only for those whose BMI is over 40 and if the percentage of ideal weight is over 180%, and then only if they have not succeeded in losing weight through other methods. Gastric by-pass blocks off most of the stomach by either stapling a part of the stomach closed (gastroplasty) or creating a small stomach pouch that serves as a reservoir and connects directly to the intestine. Both procedures limit the amount of food that a person can consume. (Gastroplasty should not be confused with the small-bowel or intestinal bypass operation, which has been universally discredited). Most people experience a 50% weight-loss within a year following the procedure, and improvement occurs in many diseases associated with obesity (diabetes, high blood pressure, sleep apnea, joint pain, and incontinence). Vomiting is the most common side effect. Complications include problems along the staple line, obstruction, and over-expansion of the pouch. Mortality rates of 1.5% have been reported. (This is still less than the risk of dying from severe obesity, however.) Patients must still develop a healthy life style after the operation and failure can occur if people cheat the procedure by eating frequent small meals of liquid or soft foods. Follow-up must be life long.

Recent Literature
Appetite suppressants and valvular heart disease (and other articles), The New England Journal of Medicine, 9/10/98

Binge Eating, Women's Health Watch. January 1997

Bulking up fiber's healthful reputation. FDA Consumer, July/August 1997

Caution for new diet drug. HealthNews, 3/31/98

Dieter's brews make tea time a dangerous affair. FDA Consumer. July/August 1997

Diet pills redux, and others.. The New England Journal of Medicine. August 28, 1997

Dual effects of weight and weight gain on breast cancer risk. JAMA, 11/5/97, Vol. 278, pp. 1407-11

The effect of age on the association between body-mass index and mortality, The New England Journal of Medicine, 1/1/98, Vol 338, p 1

Exercise Rx for maintaining weight loss. HealthNews, October 7, 1997

The facts about fats. Consumer Reports on Health. March 1997

High prepregnancy body-mass index -- a maternal-fetal risk factor, The New England Journal of Medicine, 1/15/98, Vol. 338, pp. 1919-192

High-protein diets: Where's the beef? Harvard Health Letter. January 1997

Losing weight -- an ill-fated New Year's resolution. The New England Journal of Medicine, 1/1/98

Low fat better than counting calories to keep off lost pounds. HealthNews. February, 1997

A mutation in the human leptin receptor gene causes obesity and pituitary dysfunction. Nature, March 1998. Vol 392: pp 398-401

The skinny on weight loss. Consumer Reports on Health, February 1998

Obesity. The New England Journal of Medicine, 8/7/97

Obesity without sleep apnea is associated with daytime sleepiness. Archives of Internal Medicine, 6/22/98, Vol 158: pages 1333-7

Predicting obesity in young adulthood from childhood and parental obesity. The New England Journal of Medicine, 9/25/97

A prospective study of body mass index, weight change, and risk of stroke in women. JAMA, 5/21/97

Relationship of physical activity and television watching with body weight and level of fatness among children: Results from the third national health and nutrition examination survey. JAMA, 3/25/98, Vol. 279, pp. 938-942

Very low fat diets questioned. Harvard Health Letter, December 1998

What should a man weight? Harvard Men's Health Watch, April 1998

Well-Connected Board of Editors

Harvey Simon, M.D., Editor-in-Chief 
Massachusetts Institute of Technology; Physician, Massachusetts General Hospital

Masha J. Etkin, M.D., Gynecology 
Harvard Medical School; Physician, Massachusetts General Hospital

John E. Godine, M.D., Ph.D., Metabolism 
Harvard Medical School; Associate Physician, Massachusetts General Hospital

Daniel Heller, M.D., Pediatrics 
Harvard Medical School; Associate Pediatrician, Massachusetts General Hospital; Active Staff, Children's Hospital

Irene Kuter, M.D., D. Phil., Oncology
Harvard Medical School; Assistant Physician, Massachusetts General Hospital

Paul C. Shellito, M.D., Surgery
Harvard Medical School; Associate Visiting Surgeon, Massachusetts General Hospital

Theodore A. Stern, M.D., Psychiatry
Harvard Medical School; Psychiatrist and Chief, Psychiatric Consultation Service, Massachusetts General Hospital

Carol Peckham, Editorial Director

Cynthia Chevins, Publisher




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