Losing Weight (and Keeping it Off)
One of the most important ways to preserve good health is to control your weight. By shedding pounds, overweight people can reduce their risk of type 2 diabetes, high blood pressure, and coronary heart disease (CHD). Losing weight may lower levels of low-density lipoprotein (LDL) cholesterol, which is often referred to as "bad" cholesterol. Losing weight can also lower levels of triglycerides and even increase high-density lipoprotein (HDL) cholesterol, referred to as "good" cholesterol. In addition, weight loss can help reduce the risk of osteoarthritis and gallstones.
In theory, weight control is a simple matter of balancing energy intake (the calories supplied by food) with energy output (the calories expended by physical activity and metabolism). To lose weight, you need to expend more energy than you take in. In practice, however, the task is clearly not that simple. While the basic principle of energy balance remains true, several mechanisms—genetic, metabolic, and environmental—control how much you eat and how your body uses and stores energy.
Even if some of the components involved in weight regulation are beyond your control, however, other factors within your control have a significant impact on your weight. Here's what you need to know to lose weight and keep it off:
- How does the body use and store energy?
- What factors affect body weight?
- What are the medical consequences of obesity?
- Are you overweight?
- What's the best way to lose weight and keep it off?
- Which diet plan is right for you? (PDF)
- What are the medical and surgical treatments for severe obesity?
How does the body use and store energy?
A certain amount of calories are needed to supply the energy required for everyday activities and metabolism (the chemical process by which the body converts food into energy and various functions, including food digestion, circulation, and temperature regulation). When more calories are consumed than are needed, these extra calories are stored primarily as fat—whether the calories come from fat, carbohydrates, or proteins.
During digestion, enzymes in the small intestine break down carbohydrates into simple sugars like glucose, proteins into amino acids, and triglycerides (dietary fat) into fatty acids and glycerol. Simple sugars and amino acids are rapidly absorbed from the small intestine into the bloodstream. The liver converts other sugars, like fructose and lactose, into glucose, which is used as a source of energy. Amino acids can be used as an energy source but serve mainly as building blocks for body proteins. Fatty acids combine with bile salts to form tiny droplets that promote their entry into cells in the intestinal wall, where they are again formed into triglycerides. The triglycerides are packaged into transport lipoproteins, which carry the triglycerides to the adipose tissue (fat) for storage.
Any excess carbohydrates and protein not immediately used for energy are converted to glycogen and triglycerides in the liver. These triglycerides are transported from the liver on another lipoprotein for storage in individual adipose tissue cells, located just beneath the skin or around the intestines.
To store more fat, the body either creates more fat cells (a process called hyperplasia, which generally occurs only in childhood-onset obesity, during pregnancy, or with rapid weight gain in adults) or enlarges existing fat cells (hypertrophy, the primary way that adults increase their adipose tissue). If faced with a shortage of calories—as when a person diets—the body uses the fat stored in these cells as a source of energy. Unfortunately, once fat cells are formed they can shrink, but they are not eliminated.
What factors affect body weight?
Controllable factors—such as a high-calorie diet, inappropriate psychological responses to food, and a lack of exercise—play a critical role in the development of obesity. But research has confirmed that more is involved than just a lack of willpower or a sedentary lifestyle.
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Risk factors that cannot be changed
Although these factors are beyond your control, their impact on weight can be modified by changes in diet and physical activity.
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Studies show that 80 percent of children born to two obese parents will themselves become obese, compared with 14 percent of children born to normal-weight parents. However, studies comparing the weights of adoptees with the weights of their biological and adopted parents indicate that genetic factors are responsible for only about one third of the variance in weight, a figure experts believe is more accurate. Heredity seems to influence the number of fat cells in the body, how much and where fat is stored, and the resting metabolic rate.
A number of genes appear to be responsible for the regulation of body weight. A major advance occurred in 1994 when researchers at Rockefeller University discovered that mutations in a gene—termed the obesity (ob) gene—in one strain of mice prevented them from producing leptin, a hormone normally manufactured by adipose tissue cells and released into the bloodstream to inform the brain about the body's level of fat stores. When this communication system works correctly, the hypothalamic area of the brain responds to leptin by reducing appetite and speeding up metabolism to maintain a normal level of body fat. Because mice with the mutated ob gene did not produce leptin, their brains continued to prompt the storage of fat, and they became obese. When leptin was injected into these obese mice, they quickly lost weight through a combination of decreased food intake and increased activity. Unraveling the links between leptin and weight may lead to the development of more-effective drugs for weight loss.
This is the process that extracts and utilizes energy (measured in calories) from food. Even at rest, energy is needed for many functions, such as respiration, digestion, heart contractions, and cell repair and growth. The amount of energy used for these basic functions while a person is awake and at rest is known as the resting metabolic rate, which accounts for about 70 percent of energy utilization each day (although this percentage is lower in physically active individuals). RMR is affected by weight, age, and the ratio of lean tissue (muscle) to adipose tissue (fat), since muscle is metabolically more active than fat—that is, muscle utilizes more energy even at rest.
Whether or not obese people have an abnormally slow metabolism is a matter of controversy. Because it takes more energy to maintain a greater body mass, a person who weighs 200 lbs. has a higher RMR than one who weighs 150 lbs. In addition, a heavier person expends more calories than a leaner one for any given physical activity. But even when people of the same height, weight, age, sex, and body mass are compared, RMR may vary by 20 percent or more. Consequently, someone who would be predicted to use 1,200 calories through RMR may actually use anywhere from 1,080 to 1,320 calories. This variability could explain why two people who weigh the same may require different amounts of calories to maintain, lose, or gain weight.
According to this theory, each person has a predetermined level of body fat. How the body controls its fat stores is unknown, but the regulatory mechanism, sometimes called the adipostat, is probably located in the hypothalamus. The adipostat monitors body fat stores, possibly through the actions of leptin on its hypothalamic receptor, and works to maintain the prescribed level of fat, or set point, by adjusting appetite, physical activity, and RMR to conserve or expend energy. Thus, actions perceived to be voluntary, such as eating and physical activity, may be subtly controlled by the set-point mechanism.
The following known factors are amenable to individual control.
Dietary intake. Eating more calories than you expend is an important cause of obesity. Even small excesses in calorie intake can contribute to obesity over the long term. For example, a person who overeats by just 25 calories a day will consume 9,125 excess calories over the course of a year and so will gain 2 1/2 pounds (a pound of body fat is equivalent to 3,500 calories). A woman weighing 125 pounds who starts this pattern at age 20 will weigh 175 pounds by the time she is 40.
To point to overeating as the cause of obesity is overly simplistic, however. Numerous other factors contribute to weight gain, including RMR and physical activity. Nevertheless, a reduction in calorie intake is essential for weight loss.
Physical activity. Variations in physical activity can have a tremendous impact on total daily energy expenditure. A sedentary person may burn just a few hundred calories above RMR while going about daily activities (performing household chores or walking to the mailbox, for example), whereas an athlete can burn an additional 3,000 calories each day through vigorous exercise. Regular exercise not only burns calories but also builds lean muscle mass and raises RMR because muscle requires more energy for maintenance.
Behavioral and psychological issues. Several psychological factors affect weight control. The message to eat often comes from external cues rather than hunger—noon means it's time for lunch, for example. Food and emotions are closely linked; many people use food for comfort or to release tension. The amount of exercise a person engages in is also shaped by habit and attitudes toward physical activity. Some studies suggest that lean people may expend more energy than obese people in ordinary activities, as well as during formal exercise. For example, lean people may walk around (rather than sit) while on the phone, or they may take the stairs rather than an elevator or escalator.
Hormonal (endocrine) abnormalities. An underactive thyroid (hypothyroidism) is often a layperson's explanation for obesity, but even when present, hypothyroidism is rarely a primary cause. Other conditions that may affect weight include polycystic ovary disease, tumors of the pituitary or adrenal glands, an insufficient production of sex hormones, and insulin-producing tumors of the pancreas. Although they are uncommon, these disorders need to be ruled out by a thorough medical evaluation before determining the best course of action to achieve weight loss.
What are the medical consequences of obesity?
Overweight and obesity are linked with an increased risk of life-threatening conditions, such as type 2 diabetes, coronary heart disease, and cancer. Studies show that mortality rates are substantially higher in obese adults, especially in those whose excess fat is stored in the abdomen rather than in the hips. In fact, abdominal obesity is particularly dangerous because it leads to resistance to the actions of insulin, the hormone that regulates blood glucose. Insulin resistance results in elevated blood levels of insulin, which is associated with high triglycerides, low HDL cholesterol, high blood pressure, and increased CHD risk, a constellation of conditions called metabolic syndrome. Almost 1 in 4 American adults has metabolic syndrome, which increases the risk of diabetes, coronary heart disease, and strokes.
Excess weight also increases the risk of gallbladder disease and places greater stress on the back, hips, and knees, which may aggravate arthritis.
Anyone who is over age 40 or has health problems should have a thorough medical evaluation prior to beginning a weight loss program. In addition, your physician may refer you to a nutritionist for an assessment of eating habits.
1. Medical history
The medical history will include the following:
Weight history. Your physician will determine how long you have been overweight, because obesity present since childhood may reflect a genetic predisposition and is often more difficult to treat than adult-onset obesity. Other questions may address dieting history:
Medical history. Do you have any symptoms or history of obesity-related disorders (such as CHD, stroke, hypertension, cancer, or diabetes)? Are there any symptoms suggesting an endocrine cause of obesity, such as hypothyroidism?
Family history. Is obesity prevalent in your family? Is there a family history of any obesity-related disorders?
Medications. Drugs that can cause weight gain, increase appetite, or hinder weight loss include corticosteroids, progestins, tricyclic antidepressants, phenothiazines, lithium, sulfonylureas, thiazolidinediones, and insulin.
Depressive symptoms. Depression affects many overweight people, especially those who are severely obese. A thorough evaluation includes questions about mood to determine whether depression needs to be treated along with obesity.
2. Physical examination
Blood pressure, height, weight, and waist circumference are measured. The physician will look for evidence of cardiovascular disease (diseases of the heart and blood vessels), osteoarthritis, and hypothyroidism or other hormonal conditions.
Obesity is often defined as weighing 20 percent or more above ideal body weight (which varies with height, age, and gender). This definition is somewhat misleading, however, since it is not the amount of excess weight but the amount of excess adipose tissue—or body fat—that determines the threat to health. Moreover, the distribution of body fat is an important predictor of health risk—fat stored in the abdominal area is more harmful than fat stored in the hips, thighs, and buttocks. The degree of obesity is also important; a mildly obese person is at less risk for developing obesity-related conditions than someone who is morbidly obese.
In addition to height, age, and gender, a person's ideal weight depends on many factors, including body composition (the proportion of fat and muscle), body shape (where fat is deposited), and general health. The most accurate way to assess the degree of obesity is to measure the amount of body fat. Since this task is not easy to perform, doctors generally rely on surrogate measures, such as body mass index and waist circumference, or use height/weight tables.
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Height/weight tables. Height/weight tables are the most straightforward way to assess your weight, but there are drawbacks to relying solely on this method. The tables are not based on scientific calculations of ideal weight but instead are derived from height, weight, and mortality data of people seeking life insurance. Moreover, they do not take into account body composition.
Body mass index (BMI). As the result of the difficulty in directly measuring the amount of body fat and the drawbacks of using height/weight tables alone, researchers have turned to a measurement called body mass index to define obesity and its severity. BMI is a measurement of your weight as it relates to your height. BMI correlates strongly with the amount of body fat, though it does not measure it directly. Federal guidelines define overweight as a BMI from 25 to 29.9 and obesity as a BMI of 30 or greater. Morbid obesity is a BMI of 40 or greater.
Waist circumference. While BMI is a general assessment of body weight and disease risk, waist circumference provides an added and more specific measure of health risk because waist circumference indicates harmful abdominal fat. Research shows that the mortality rates and incidence of certain chronic diseases, such as diabetes and high blood pressure, are substantially higher in those with a disproportionate amount of body fat stored in the abdomen.
Fortunately, abdominal fat is often the first to go with weight loss. Typically, men are prone to fat deposition in the abdomen—developing what is commonly called a pot belly or beer belly—whereas women tend to accumulate fat around the hips, buttocks, and thighs. However, women are not immune to accumulating abdominal fat, and weight tends to be stored in a pattern typical to a particular individual. Even in people of normal weight, an increased waist circumference may be linked to an elevated health risk. (A normal waist circumference is less than 40 inches in men and less than 35 inches in women.) And in men and women who are overweight or obese, a large waist circumference increases the already elevated risk of disease.
Techniques for measuring body fat. Obesity is defined as fat stores exceeding 25 percent of total body weight for men or 30 percent for women. Direct measurement of the amount of body fat is the most accurate way to determine obesity-related health risk. A variety of methods can be used to estimate body fat, including underwater weighing (hydrodensitometry), dual-energy X-ray absorptiometry (DEXA), and bioelectrical impedance analysis. However, none of these techniques are exact, some are expensive and not widely available, and all require trained personnel to administer them. Thus, they are not practical for general use.
Laboratory tests. Blood will be drawn to measure total and HDL cholesterol, triglycerides, liver function, and blood glucose to screen for some of the complications of obesity. If a thyroid abnormality is suspected, thyroid stimulating hormone is often measured.
What's the best way to lose weight and keep it off?
Successful weight loss requires a three-pronged approach: changing behavior patterns, making dietary adjustments, and increasing physical activity. Culled from medical research, the following guidelines incorporate strategies employed by people who have lost weight and kept it off. Use them to construct a weight loss program on your own or as an adjunct to medical or surgical treatments.
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An ability to alter lifelong attitudes toward diet and exercise may ultimately be the key to successful weight management: You must be motivated enough to change habits not for a few weeks or months but for a lifetime. The importance of this resolve cannot be underestimated. Choosing the right time to start a weight-loss program is also important. People under stress or pressure may not be able to devote the considerable attention and effort required to make lifestyle changes.
If you are motivated and ready to lose weight, the following guidelines will help.
1. Set realistic goals. Instead of attempting to lose a specific number of pounds, make it your goal to adopt more healthful eating and exercise habits. If you are obese and feel compelled to set a weight goal, losing 10 percent to 15 percent of your current body weight is a realistic objective. The safest rate of weight loss is 1/2 to 2 pounds a week.
2. Seek support from family and friends. People who receive social support are more successful in changing their behaviors. Ask family and friends for help, whether this means keeping high-fat foods out of the house or relieving you of some chore so that you have time to exercise. It will be easier to stick to your new eating plan if everyone in the household eats the same types of foods. You may be more motivated to exercise if you work out with a friend or family member.
3. Make changes gradually. Ease into exercise; do not overdo it. Incorporate low-fat eating in stages. For example, if you typically drink whole milk, switch to reduced-fat (2 percent) milk, then to low-fat (1 percent), and then to fat-free milk.
4. Eat slowly. Many people consume more calories than needed to satisfy their hunger because they eat too quickly. Since it takes about 20 minutes for the brain to recognize that the stomach is full, slowing down helps you feel satisfied on less food.
5. Eat three meals a day, plus snacks. Skipping meals is counterproductive, as is severely reducing food intake, since such strict changes are impossible to maintain and are ultimately unhealthful. You will be more successful in the long run if you allow yourself to eat when you are hungry, eat enough nutritious low-fat food to satisfy that hunger, and spread your calorie intake over the course of the day.
6. Plan for exercise. Choose activities that are convenient and enjoyable, and then treat exercise like any other appointment—set a time and jot it down in your datebook.
7. Evaluate your relationship to food. Behavioral and emotional cues frequently trigger an inappropriate desire to eat. The most common cues are habit, stress, boredom, sadness, anxiety, loneliness, and the use of food as a reward. Many people also relate food to love or care and derive comfort from it. Although eating may appear to soothe uncomfortable feelings, its effect is temporary at best and ultimately does not solve any problems. In fact, it may distract you from focusing on the real issues.
8. Don't try to be perfect. While losing weight requires significant changes in eating and exercise habits, not every high-calorie food must be banished forever, and you need not exercise vigorously every day.
To determine how many calories you should eat per day, first calculate the number of calories needed to maintain your current weight—roughly 15 calories per pound of body weight in a moderately active person (someone who gets at least 30 minutes of moderate to intense physical activity every day). A completely sedentary person may require just 12 calories per pound to maintain weight.
A pound of body fat contains 3,500 calories. To lose 1 to 2 pounds per week—a gradual and safe rate of weight loss—you must eat 500 to 1,000 fewer calories per day than what is needed to maintain your weight. (The calorie cutback need not be so severe if you also begin to exercise regularly.) Calorie intake should not drop below 1,200 per day in women or 1,500 per day in men (unless the diet is medically supervised and you are taking a vitamin/mineral supplement), since it would be difficult to get all the nutrients you need.
While reducing calorie intake is essential for losing weight, focusing on calories per se may leave people feeling hungry and frustrated unless the overall composition of the diet is also considered. Replacing dietary fat with complex carbohydrates automatically lowers calorie intake, while allowing a satisfying volume of food. There are other reasons to reduce the fat content of your diet. Some evidence suggests that a prolonged high-fat diet may trigger an upward adjustment in the body's set point. In addition, fewer calories are burned when dietary fat is converted into body fat than when carbohydrates or protein are converted into fat. Moreover, a low-fat diet can help to lower blood cholesterol levels and may reduce the risk of colon and prostate cancer.
Once you decide on an appropriate calorie intake, you need to determine the amount of total fat you should eat. Most experts now recommend that a diet should derive no more than 35 percent of its calories from fat (even when substituting monounsaturated for saturated fats). Most people should not reduce fat intake to less than 20 percent of calories, and the American Heart Association cautions against cutting fat below 15 percent for certain groups of people (older adults, for example), owing to concerns over malnutrition and a possible negative effect on blood lipids.
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- Tips for adopting a low-fat, high-complex-carbohydrate diet
- Low-carb (high-protein) diets
- Which diet plan is right for you?
Tips for adopting a low-fat, high-complex-carbohydrate diet
1. Eat mostly fruits, vegetables, legumes, and grains. These foods are naturally low in fat and high in fiber. (Fiber provides bulk, which helps to fill you up without adding calories.)
2. Do not add fat during cooking. Avoid sautéing foods in butter or oil. Bake, broil, steam, or roast foods instead of frying them.
3. Choose lean cuts of meat and poultry. Meat and poultry contain a lot of fat. Top round, eye of round, and round are the leanest cuts of beef; tenderloin, top loin, and lean ham are the leanest pork cuts; and light-meat chicken and turkey are leaner than dark meat. Do not eat poultry skin—it contains a lot of fat. But you can leave it on during roasting or baking to help keep the meat moist and tender; just be sure you do not cook the poultry with other ingredients, such as potatoes, that could absorb the fat released from the skin as it cooks. Limit portion sizes to 3 ounces—about the size of a deck of cards—and round out the meal with plenty of grains and vegetables.
4. Switch to low-fat or fat-free dairy products. Whole milk and cheeses can contain more fat than meat. But do not eliminate dairy products: They are an important source of calcium and protein.
5. Read food labels. The nutrition labels that are required on all packaged foods provide important information about their calorie and fat content, which makes it easy to compare brands.
6. Use fat substitutes judiciously. While fat substitutes definitely reduce the number of calories consumed from fat and saturated fat, their impact on total caloric intake and body weight, as well as general health in the long term, is uncertain. And one fat substitute, olestra—used in some chips and crackers—inhibits the absorption of fat-soluble nutrients. Vitamins A, D, E, and K are added to products to offset this effect.
7. Watch out for hidden fats. It is easy to overlook the fat and calories contributed by toppings such as margarine, cream sauce, mayonnaise, salad dressings, peanut butter, sour cream, and cheese. Limit the amounts of these items, or choose low-fat versions.
8. Consider the calories in beverages. Although regular soda, fruit juices, and alcoholic beverages are fat free, they contain a significant number of calories. And, with the exception of citrus juices, these beverages are not a good source of vitamins and minerals. Choose calorie-free beverages—water or seltzer, and moderate amounts of coffee and tea—most of the time.
9. Control portion sizes. According to recent research, almost all foods and beverages currently sold in the United States are excessive in size and dramatically increased from their original sizes. Hamburgers, french fries, and sodas are two to five times as large as they used to be in the 1970s. In addition, the average American eats about four restaurant meals a week; studies show that most restaurant meals are not only larger in size than home-cooked meals but also higher in calories, saturated fat, and sodium while being lower in fiber and calcium.
To get an accurate picture of the amount of food you normally eat, serve yourself a typical portion, then use a measuring cup, measuring spoon, or food scale to measure or weigh the food. Next, try serving yourself a smaller portion. You can dispense with weighing and measuring food once you become accustomed to estimating smaller portion sizes.
Popular "fad" diets have been around for decades and are appealing because they often result in rapid, seemingly effortless weight loss, at least initially, owing to loss of body water. Recently, there has been an enormous resurgence in the popularity of low-carbohydrate (high-protein) diets. Such diets promote the same basic idea that was put forth in the 1960s: Eat high-protein foods (such as meat and eggs), and restrict carbohydrate-rich foods (such as potatoes, pasta, fruits, and certain vegetables).
Once relegated to the realm of quackery, these diets are being advocated because carbohydrates are thought to promote weight gain by increasing the body's production of insulin, which speeds up the conversion of food to body fat. Proponents of low-carbohydrate diets also claim that carbohydrates are less filling than other foods, causing people to consume more calories in an effort to satisfy their hunger. Furthermore, in some people, a low-fat, high-carbohydrate diet has been shown to raise triglyceride levels and lower HDL cholesterol levels—two components of metabolic syndrome, which can lead to heart disease and type 2 diabetes.
High-protein diets are being taken seriously by some researchers who recognize that people can lose weight on them. In two recent studies, overweight and obese people who were placed on a diet very low in carbohydrates lost more weight over a six-month period than subjects who followed a low-fat, reduced-calorie diet. However, in both studies, there was no significant difference between the two groups in the amount of weight lost after a year of following the diets. These findings indicate that a low-carbohydrate diet produces more weight loss initially but that dieters following a low-fat diet continue to lose weight over time. More research is needed to determine whether dieters following a low-carbohydrate diet can maintain weight loss or continue to lose weight over a longer period of time.
Furthermore, the long-term effects of a low-carbohydrate diet, which is typically heavy on meat and saturated fat, on coronary heart disease are currently unknown. In the aforementioned studies, subjects following the low-carbohydrate diet experienced a reduction in triglyceride levels and an increase in HDL levels; however, these lipid changes are typical following weight loss. Future studies need to evaluate lipid changes on a long-term basis.
Moreover, the long-term effects of a diet devoid of antioxidants and phytochemicals from fruits, vegetables, and whole grains, which are very restricted on a low-carbohydrate meal plan, are unknown.
Also, several specific health concerns are associated with a diet that places such a heavy emphasis on the consumption of protein and the restriction of carbohydrate. Consuming too much protein places extra stress on the liver and kidneys because they have to metabolize and excrete more than normal amounts of waste products. Kidney stones can be caused or aggravated by the high uric acid levels created by high-protein foods. And for those who have diabetes or kidney disease, high-protein diets may speed the progression of kidney disease, even if the diet is followed for a short time. Furthermore, some studies suggest that eating too much protein causes excessive calcium loss, which can contribute to osteoporosis.
Restricting carbohydrate intake is unhealthy as well. Drastically reducing carbohydrate consumption increases the metabolism of fatty acids and causes ketosis. This condition results when excessive amounts of acidic substances known as ketone bodies are released into the bloodstream. Ketosis can be dangerous for people with known or unrecognized heart disease, diabetes, or kidney problems. In addition, restricting carbohydrates can lead to vitamin and mineral deficiencies. Healthful, carbohydrate-rich foods, such as whole grains, fruits, and vegetables, provide essential nutrients as well as fiber and phytochemicals that work together to help prevent disease and promote good health. In fact, one of the basic underlying problems with most high-protein diets is their failure to promote a balanced diet and to teach long-term healthful eating habits.
High-protein, low-carbohydrate diets are best used selectively on a short-term basis, if at all, and under medical supervision. The many limitations and risks associated with high-protein diets raise important questions about their long-term safety and effectiveness. In fact, a 2003 advisory by the American College of Preventive Medicine states that there is currently little evidence to support the safety and effectiveness of popular diets that promote unlimited consumption of protein or fat.
Exercise is a valuable element in a weight loss program, but exercise alone results in only modest weight loss and at a slower rate than calorie restriction. Although combining it with diet results in greater loss of weight and body fat than dieting alone, exercise is especially important for maintaining weight loss. And adding exercise to calorie restriction makes the dietary changes easier because they need not be as drastic. It is easy to see why this is so. To lose 1 pound per week requires a deficit of about 500 calories a day. By adding a half hour of moderate to vigorous exercise per day (enough to burn 250 calories), you reduce the dietary restriction to a more manageable 250 calories per day.
The effect of exercise is cumulative. For example, while it takes about nine hours of walking at a normal pace for a 175-pound person to burn 3,500 calories, the walking does not have to be completed all at once. You can achieve the same calorie deficit if you walk for half an hour each day for 18 days or an hour for nine days. You can even break up an exercise session into segments: for example, a 10-minute walk in the morning, 10 minutes at lunch, and 10 minutes in the evening still burn the same number of calories as a single 30-minute walk.
Start an exercise program gradually. Trying to do too much, too soon may lead to muscle strain and soreness, or even injury, which may lead to the desire to quit. And remember that sedentary people over the age of 50 should consult their doctor before starting any vigorous exercise program.
1. Increase your amount of everyday physical activity. Look for ways to add physical activity into your lifestyle: For example, walk rather than drive, or take the stairs rather than an elevator or escalator.
2. Add a formal walking program. Walking is appealing because it can be done anywhere and requires no special equipment (other than a supportive pair of shoes), and almost anyone can do it. Set your own pace: You expend approximately the same number of calories during an hour of slow walking as in half an hour of brisk walking. Start by walking for half an hour, three times a week. Once you become comfortable with this level of activity, walk for the same length of time five days a week. Next, gradually increase the duration of your walking to 40 minutes, then 50 minutes, and ultimately an hour. As you become more physically fit, you will be able to walk faster and go farther—and thus burn more calories in a given period of time.
3. Vary your activities. If you enjoy walking, make it the foundation of your exercise program. To prevent boredom, and also to work different muscle groups, choose other activities to substitute for walking on some days. Good choices include aerobic dance classes, bicycling, line dancing, or swimming. The most important rule, however, is to engage in activities that are enjoyable and convenient to do regularly.
4. Start a weight-training program. Working a muscle against resistance increases muscle size and strength.
What are the medical and surgical treatments for severe obesity?
Because the following treatments can be demanding for the patient and carry the risk of adverse side effects, they are appropriate only for people who are severely obese—especially those with, or at high risk for, medical conditions that may be improved with weight loss.
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Very-low-calorie and low-calorie diets
The term very-low-calorie diet is used to describe diets supplying fewer than 800 calories a day. Typically, patients must replace food with a powdered supplement that is combined with a noncaloric liquid (water or diet soda). To prevent deficiencies, the supplement is primarily made of high-quality protein derived from milk, eggs, or soy, along with a small amount of carbohydrates, minimal fat, and added vitamins and minerals. The high protein content of these diets is essential to help preserve muscle mass when calorie intake is so low.
Recently, many centers modified their VLCD formulas to contain more calories. Studies have shown that weight loss is about as good on 800 as on 400 to 500 calories a day, and there are probably fewer risks. The term low-calorie diet is used to describe diets that supply from at least 800 calories per day to slightly below the person's daily caloric expenditure. So for a person needing 2,000 calories per day, a VLCD is up to 799 calories, and an LCD is 800 to 1,999 calories. (Although a program may be referred to as a low-calorie diet, or LCD, we will use VLCD to describe both types, except where the protocols differ.)
Typically lasting 12 to 16 weeks, VLCDs require close medical supervision and are usually administered by weight loss clinics or hospitals. Programs should include regular medical monitoring, behavioral counseling to help you adjust to the diet, and instruction for changing eating patterns once food is reintroduced. Programs may also provide classes and support groups; many place a great emphasis on exercise. Once the VLCD phase is completed, food is slowly reintroduced over two to 10 weeks. The cost of participation is around $2,000 to $3,000. Few insurance companies cover this cost.
VLCDs are appropriate for people with a body mass index of 35 or higher who have been unable to lose weight with conventional diet and exercise. LCDs are appropriate for individuals with a BMI between 30 and 34.9, especially for those who have coexisting conditions, such as type 2 diabetes, hypertension, high triglycerides, low HDL cholesterol, sleep apnea, or osteoarthritis.
Contraindications to VLCDs include a recent heart attack or stroke, heart rhythm abnormalities (arrhythmias), angina, liver or kidney disease, or type 1 diabetes. However, insulin-treated, obese patients with type 2 diabetes can benefit from VLCDs.
For people who can stay on them, VLCDs produce dramatic reductions in weight. On average, participants lose 2.5 to 4 pounds per week, at a rate that tends to slow as the duration of the VLCD increases to months.
Despite the dramatic success possible with VLCDs, they are not a panacea. About 25 percent of people who start a VLCD cannot adhere to the strict regimen and drop out of the program. Most of those who do complete treatment regain large amounts of weight within a year or two, typically reaching pretreatment weight within five years.
VLCD programs are worthless without detailed attention to long-term maintenance. You must learn to overcome the eating and behavioral patterns that contributed to your obesity in the first place—and you ultimately must make daily food choices on your own.
In general, VLCDs are safe when medically supervised. Early side effects of hunger, fatigue, and light-headedness usually subside within two weeks. People who cannot tolerate milk products may react to a dairy-based formula. Later on, dieters may note constipation and intolerance to cold, and the risk of gallstones is increased.
Whether the treatment of obesity requires medication is a decision that must be made on a case-by-case basis. Drug therapy was never intended to be anything but a last-choice option when no other treatment had worked. And today, the use of medications to help suppress appetite or otherwise alter the body's energy balance remains a controversial area in obesity management. Drugs should be used only in people whose BMI exceeds 30 or exceeds 27 when accompanied by serious medical conditions that could be improved by weight loss. Anorectics—drugs that reduce appetite—do not magically melt away pounds: While they may make it easier to adhere to lifestyle changes, they do not eliminate the need to alter behavior permanently.
For good results, drug therapy must be combined with extensive dietary, exercise, and behavior modifications. Anorectics are not effective for everyone. For example, people whose excessive eating is triggered by habits, stress, or emotions may benefit less from drugs that reduce appetite than those who eat because of hunger. If no weight is lost in the first week or two of use, the drug is unlikely to help and should be discontinued (consult your doctor first). Following are the types of drugs currently in use:
Antidepressants. Although the Food and Drug Administration has not approved antidepressants for the treatment of obesity, patients taking the selective serotonin reuptake inhibitors fluoxetine (Prozac) or sertraline (Zoloft) for depression often experience weight loss. Typically, doctors prescribe these drugs for weight loss if the patient is also depressed. SSRIs increase brain levels of serotonin, which produces feelings of fullness. Thus, some patients taking SSRIs feel less hungry, are less concerned with food, and are better able to control their appetites, though the effect may not last long.
Lipase inhibitor. Orlistat (Xenical) blocks the intestinal absorption of about 30 percent of dietary fat. Side effects—such as cramping, oily anal leakage, and explosive diarrhea—tend to be worse when patients eat greater quantities of fatty foods. These adverse effects discourage the consumption of such foods and contribute to the effectiveness of the drug. Because fat malabsorption associated with orlistat can lead to a loss of fat-soluble vitamins A, D, E, and K in the stools, a multivitamin must be taken with this medication.
Noradrenergics. These drugs increase levels of norepinephrine (noradrenaline) in the brain. Norepinephrine reduces appetite by stimulating the central nervous system. On average, people taking a noradrenergic lose about 1/2 pound more per week than those taking a placebo. A noradrenergic agent called phenylpropanolamine, present in several medicines and over-the-counter appetite suppressants such as Dexatrim, was recalled by the FDA in November 2000.
Serotonin/norepinephrine reuptake inhibitor. The drug sibutramine (Meridia) enhances both serotonin and norepinephrine levels in the brain. This action promotes feelings of fullness and thus reduces appetite. Studies show that patients who took sibutramine while on a reduced-calorie diet showed significant weight loss during the first six months of treatment. In addition, significant weight loss was maintained for one year. Because of the potential for adverse effects, such as increased blood pressure, sibutramine has come under increased scrutiny. Additional research is currently underway to evaluate the safety of this drug.
Each year, approximately 100,000 Americans undergo bariatric surgery for the treatment of severe obesity. Bariatric surgery is considered for morbidly obese people or for obese people with significant complications of obesity.
Bariatric surgery does not remove fat tissue by suction or excision; rather, it usually involves reducing the size of the stomach. The three commonly used types of bariatric procedures are vertical banded gastroplasty, laparoscopic adjustable gastric banding, and gastric bypass.
Vertical banded gastroplasty. This surgery, also called gastric partitioning, is a gastric restriction procedure that divides the stomach into two sections. A stapling instrument is used to section off a golf-ball-size pouch at the top of the stomach, and an inflexible ring (or band) is put in place to encircle the small opening between the pouch and the rest of the stomach. This procedure allows small amounts of food to pass from the pouch to the remaining portion of the stomach. The likelihood of overeating is reduced because a small quantity of food creates a feeling of fullness. Several studies have shown that vertical banded gastroplasty may result in significant weight loss and improvement in weight-related medical conditions, although there are some side effects and risk, which include deterioration of the band or staple line. More commonly, people who undergo this procedure experience vomiting from overstretching the stomach. The risk of infection or death from complications of vertical banded gastroplasty is less than 1 percent.
Laparoscopic adjustable gastric banding. Approved for use by the Food and Drug Administration in June 2001, this gastric restriction procedure cuts off a portion of the stomach to reduce gastric volume without stapling. Using laparoscopic techniques, an adjustable, hollow, silicone band ("Lap-Band") is wrapped around the upper part of the stomach to create a small pouch. Attached to the band is a flexible tube connected to a miniature access port, which is implanted just beneath the skin of the abdomen. Using this reservoir system, a physician can remove or add saline solution to the band to adjust its fit around the stomach and change the size of the narrow passage that connects the pouch to the lower stomach. Unlike some other gastric surgeries, laparoscopic gastric banding is reversible.
Gastric bypass. This procedure is done in combination with gastric restriction. The volume of the stomach is first reduced by using a stapling tool to create a small upper gastric pouch that is completely separated from the rest of the stomach. The small pouch decreases the quantity of food an individual can comfortably consume. A segment of the small intestine is then surgically rerouted to connect directly to the gastric pouch. This procedure allows ingested food to bypass the majority of the stomach as well as part of the small intestine. Since nutrient absorption takes place in the small intestine, the number of calories available to the body is reduced by limiting both the amount of time food spends there and the amount of the small intestine exposed to food and thus available to absorb it. The risks associated with gastric bypass are similar to those of vertical banded gastroplasty. However, approximately 30 percent of bypass patients also develop nutritional deficiencies. According to clinical studies, gastric bypass is effective for initiating and sustaining weight loss.
While the surgical removal of fat may seem like an ideal method of weight reduction, liposuction is, at best, a questionable solution. Unlike diet and exercise, fat reduction via liposuction has no proven health benefits. And the procedure cannot help those who are diffusely overweight. Instead, liposuction is appropriate only for people of normal or near-normal weight who have stubborn fat deposits that do not respond to diet and exercise. Candidates should also be in good general health and have skin that is elastic enough to shrink evenly after the surgery—which rules out many people over 50. Finally, liposuction comes with no cosmetic guarantees: While the extracted fat cells will not return, weight can still be gained at other sites in the body. Common sites of liposuction include the abdomen, hips, buttocks, thighs, legs, upper arms, face, and neck; sometimes several areas are treated at once. While the overall risk associated with liposuction is low, the more fat that is removed, the greater the risk of complications such as infection or blood clots.
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