Obesity is excess body weight.
- Obesity usually results from consuming too many calories and not burning enough calories in physical activity.
- Being obese increases the risk of many disorders, such as diabetes, high blood pressure, heart disease, and certain cancers, and can result in early death.
- Increasing activity and reducing caloric intake are essential to treating obesity, but some people also need to take drugs.
- Losing as little as 5 to 10% of body weight can help lessen weight-related problems, such as diabetes, high blood pressure, and high cholesterol levels.
- People who are very obese and who have serious weight-related problems may benefit from weight-loss surgery.
BMI does not distinguish between muscle (lean) and fat tissue. Thus, based on BMI alone, some people may be labeled obese when their percentage of body fat is very low. For example, some people, such as body builders, have a high BMI because they have a large amount of muscle (which weighs more than fat), even though they have very little fat. Such people are not considered obese.
Obesity has become increasingly common throughout the world. In the United States, obesity is very common. Almost 36% of adults are obese, and about 17% of children and adolescents are overweight or obese. Also, severe obesity has become more common.
Obesity is much easier to prevent than treat. Once people gain excess weight, the body resists losing weight. For example, when people diet or reduce the number of calories they consume, the body compensates by increasing appetite and reducing the number of calories burned during rest.
Categories of weight are defined as follows:
- Underweight = less than 18.5
- Normal = 18.5 to 24.9 (18 to 22.9 for Asians)
- Overweight = 25 to 29.9 (23 to 29.9 for Asians)
- Obese = 30 to 40
- Obese, severe (morbid obesity) = more than 40
CausesObesity results from a combination of factors, including the reduced opportunity for physical activity, the increased availability of high-calorie foods, and the presence of genes that make obesity more likely. But ultimately, obesity results from consuming more calories than the body needs over a long period of time.
Excess calories are stored in the body as fat. The number of calories needed varies from person to person, depending on age, sex, activity level, and metabolic rate. A person's resting (basal) metabolic rate—the amount of calories the body burns while at rest—is determined mostly by how much muscle (lean) tissue a person has. The more muscle people have, the higher their metabolic rate.
Physical inactivity:In developed countries, lack of physical activity contributes greatly to the increase in obesity. Opportunities for physical activity have been engineered away by technological advances, such as elevators, cars, and remote controls. More time is spent doing sedentary activities, such as using the computer, watching television, and playing video games. Also, people's jobs have become more sedentary as office or desk jobs have replaced manual labor. Sedentary people use fewer calories than more active people and thus require fewer calories in the diet. If caloric intake is not reduced accordingly, people gain weight.
Diet:The diet in developed countries is energy dense. That is, it consists of foods that have a large number of calories in a relatively small amount (volume). Most of these foods contain more processed carbohydrates (such as high-fructose corn syrup), more fat, and less fiber. Fats, by nature, are energy dense. Fat has 9 calories per gram, but carbohydrates and proteins have 4 calories per gram.
Convenience foods, such as energy-dense snacks offered at vending machines and fast food restaurants, contribute to the increase in obesity. High-calorie beverages, including soda, juices, many coffee drinks, and alcohol, also contribute significantly. For example, a 12-ounce soda or bottle of beer has 150 calories, and a 12-ounce coffee beverage (containing dairy and sugar) or fruit smoothie can have 500 or more calories. Larger portion sizes at restaurants and in packaged foods and beverages encourage people to overeat. Also, restaurant and packaged foods are often prepared in ways that add calories. As a result, people may consume more calories than they realize.
Genes:Obesity tends to run in families. However, families share not only genes but also environment, and separating the two influences is difficult. Genes can affect how quickly the body burns calories at rest and during exercise. They can also affect appetite and thus how much food is consumed. Genes may have a greater effect on where body fat accumulates, particularly fat around the waist and in the abdomen, than on how much body fat accumulates.
Many genes influence weight, but each gene has only a very small effect. Obesity rarely results when only one gene is abnormal.
Rarely, mutations in the following genes result in obesity:
- The gene for the melanocortin 4 receptor: Receptors are structures on the surface of cells that inhibit or produce an action in the cell when certain substances (such as chemical messengers) bind with them. Melanocortin 4 receptors are located mainly in the brain. They help the body regulate its use of energy. A mutation in this gene may account for obesity in 1 to 4% of children.
- The ob gene: This gene controls the production of leptin, a hormone made by fat cells. Leptin travels to the brain and interacts with receptors in the hypothalamus (the part of the brain that helps regulate appetite). The message carried by leptin is to decrease food intake and increase the amount of calories (energy) burned. A mutation in the ob gene prevents leptin production and results in severe obesity in a very small number of children. In these cases, administration of leptin reduces weight to a normal amount.
- Certain racial and ethnic backgrounds, such as black, Hispanic, and Pacific Islander
- A lower socioeconomic group
- A lower education level
- Obesity during childhood, which tends to persist into adulthood.
If a pregnant woman is obese or smokes, weight regulation in the child may be disturbed, contributing to weight gain during childhood and later.
After menopause, many women gain weight. This weight gain may result from reduced activity. Hormonal changes may cause fat to be redistributed and accumulate around the waist. Fat in this location increases the risk of health problems.
Aging:As people age, body composition may change as muscle tissue decreases. The result is a higher percentage of body fat and a lower basal metabolic rate (because muscle burns more calories).
Obesity is more than twice as common at age 55 as at age 20.
Lifestyle:Sleep deprivation or lack of sleep (usually considered less than 6 to 8 hours per night) can result in weight gain. Sleeplessness results in hormonal changes that increase appetite and cravings for energy-dense foods.
Stopping smoking usually results in weight gain. Nicotine
decreases appetite and increases the metabolic rate. When nicotine
is stopped, people may eat more food and their metabolic rate decreases, so that fewer calories are burned. As a result, body weight may increase by 5 to 10%.
Hormones:Hormonal disorders rarely cause obesity. The following are among the most common:
- Cushing syndrome is caused by excessive levels of cortisol in the body. The syndrome can result from a benign tumor in the pituitary gland (pituitary adenoma) or from a tumor in the adrenal gland or elsewhere, such as in the lungs. Cushing syndrome typically causes fat to accumulate in the face, making it look full (called moon face), and behind the neck (called a buffalo hump).
- Polycystic ovary syndrome affects about 5 to 10% of women. Affected women tend to be overweight or obese. Levels of testosterone and other male hormones are increased, causing fat to accumulate in the waist and abdomen, which is more harmful than the fat that is distributed throughout the body.
Did You Know...
- Hormonal disorders rarely cause obesity.
- Binge eating disorder is characterized by binging, by eating large amounts of food during a short amount of time, and usually by a feeling of guilt or remorse or sense of being out of control. Most affected people do not purge (for example, by vomiting or using laxatives or diuretics). The disorder is diagnosed when bingeing episodes occur at least twice a week for 6 or more months.
- Night-eating syndrome involves not eating much during the day, consuming a lot of food or calories in the evening, and awakening to eat in the middle of the night. Rarely, taking a sleeping pill, zolpidem
, can cause similar problems.
SymptomsThe most obvious symptom of obesity is a change in overall appearance.
Complications:Being obese increases the risk of many health problems. Virtually every organ system can be affected. These weight-related health problems can cause symptoms, such as shortness of breath, difficulty breathing during activity, snoring, skin abnormalities including acne, and joint and back pain.
Obesity increases the risk of the following:
- Abnormal levels of cholesterol and other fats (lipids), called dyslipidemia
- High blood pressure
- Metabolic syndrome, which includes resistance to the effects of insulin (called insulin resistance), abnormal levels of cholesterol and other fats in the blood, and high blood pressure
- Coronary artery disease
- Heart failure
- Diabetes or a high blood sugar level that is not high enough to be considered diabetes (prediabetes)
- Cancer of the breast, uterus, ovaries, colon, prostate, kidneys, or pancreas
- Gallstones and other gallbladder disorders
- Gastroesophageal reflux (GERD)
- A low testosterone level, erectile dysfunction, and reduced fertility in men
- Menstrual disorders, infertility, and increased risk of miscarriage in women
- Skin infections
- Varicose veins
- Fatty liver and cirrhosis
- Blood clots (deep vein thrombosis and pulmonary embolism)
- Obstructive sleep apnea
- Arthritis, gout, low back pain, and other joint disorders
- Depression and anxiety
Obesity can increase the risk of early death. The more severe the obesity, the higher the risk. In the United States, 300,000 deaths a year are attributed to obesity. It is the second most common cause of preventable death (cigarette smoking is the most common).
Obesity can lead to social, economic, and psychologic problems. For example, obese people may be underemployed or unemployed, or they may have poor body image and low self-esteem.
DiagnosisObesity is diagnosed by determining the BMI . The BMI does not take race, sex, and age into consideration. It also does not distinguish between lean and fat tissue. Thus, some people have a high BMI because they have excess muscle (for example, if they are body builders), but they are not considered obese. Conversely, some people have a normal weight but a high percentage of body fat, which is unhealthy. Therefore, if doctors are unsure whether a high BMI is due to muscle or excessive fat, they determine body composition (the percentage of body fat and muscle). Body composition can be determined using dual-energy x-ray absorptiometry (DEXA), which is also used to check for bone loss, or by bioelectric impedance, which can be done in a doctor's office . The percentage of body fat can also be estimated by measuring skinfold thickness (usually over the triceps, at the back of the upper arm) and the circumference of the upper arm. The skinfold is the skin and layer of fat under it that is obtained by pinching the skin.
Waist circumference is measured. This measurement helps identify and quantify abdominal (visceral) obesity, which is fat that accumulates around the waist and in the abdomen. Abdominal obesity is much more harmful than fat that is distributed throughout the body under the skin (subcutaneous fat).
Typically, blood tests are done. Blood sugar (glucose) is measured to check for prediabetes or diabetes, and cholesterol and other fat levels are measured to check for high cholesterol and other abnormal fat levels. Doctors also measure blood pressure to check for high blood pressure (hypertension). These tests help doctors determine whether people have metabolic syndrome (which includes all three disorders).
Knowing how large the waist is and whether metabolic syndrome is present helps doctors estimate the risk of serious complications better than knowing what the person's BMI is.
Doctors also check for other disorders that are common among people who are obese, such as obstructive sleep apnea, fatty liver, and depression.
TreatmentThe main treatment for obesity is changes in lifestyle, which includes changes in diet, increased physical activity, and changes in behavior. Some people may also need to take drugs or to have weight-loss (bariatric) surgery. Losing as little of 5 to 10% of body weight can help reduce the risk or severity of weight-related health problems, such as diabetes, high blood pressure, and high cholesterol levels.
Successful weight loss requires motivation and a sense of readiness. People who are most successful have realistic goals and recognize that healthy weight loss can be achieved only with lifelong lifestyle changes rather than a magic bullet or fad diet that cannot be sustained. Seeking the support of health care practitioners such as dieticians or doctors can be beneficial. Support from family members is also crucial. Programs that require regular contact increase accountability and can increase the likelihood of success. Some examples include Overeaters Anonymous (OA), Take Off Pounds Sensibly (TOPS), community-based and work-site programs, and organized commercial programs such as Weight Watchers. Typically, weekly meetings are conducted by counselors and supplemented with instructional and guidance materials.
Did You Know...
- Losing as little as 5 to 10% of body weight can reduce weight-related health risks.
The following changes in diet are recommended:
- Eating small meals and avoiding or carefully choosing snacks
- Eating breakfast (skipping breakfast can lead to consuming too many calories later in the day)
- Eating 5 or more servings of fruits and vegetables a day
- Substituting fresh fruits and vegetables and salads for refined carbohydrates and processed food
- Eating lean protein—for example, fish or chicken breast or vegetable protein, such as soy
- Switching to no-fat dairy products
- Eliminating high-calorie beverages, such as soda, juice, or alcohol, and drinking water instead
- Limiting consumption of restaurant and fast food
- Limiting alcohol consumption
- Switching from harmful fats (such as saturated fat and trans fat) to good fats, such as monounsaturated fats (found in olive and canola oils) and polyunsaturated fats (in deep-sea fish and vegetable oils), and limiting the amount of fat consumed.
No-fat or low-fat dairy products, which provide vitamin D
, should be included to help prevent a deficiency of this vitamin.
Using meal replacements, regularly or once in a while, can help some people lose weight and keep it off.
Physical activity:Increasing physical activity can help people lose weight in a healthy way and keep it off. Physical activity includes not only exercise (that is, structured physical activity) but also lifestyle activities, such as taking the stairs instead of the elevator, gardening, and walking instead of driving when possible. Lifestyle activities can burn a considerable number of calories. People who do not exercise while dieting are more likely to regain the weight they lose.
Aerobic exercise, such as jogging, walking briskly (3 to 4 miles an hour), biking, singles tennis, skating, and cross-country skiing, burn more calories than less active exercises . For example, vigorous walking can burn about 4 calories per minute, so that 1 hour of brisk walking per day burns about 240 calories. Running burns about 6 to 8 calories per minute (about 360 to 480 calories per hour). As a general guide, people need to walk at least 150 minutes each week to promote health. To lose weight and keep it off, people need to spend 300 to 360 minutes each week doing moderate physical activity or 150 minutes each week doing vigorous aerobic exercise (such as running or using an elliptical machine). Vigorous aerobic exercise, has other health benefits, including reducing the risk of coronary artery disease and increasing endurance .
To get the most benefit from exercise, people should do strength training (with weights or another form of resistance) about 3 days of the week. Strength training increases the amount of muscle tissue, which increases the metabolic rate, so that the body burns more calories when at rest.
Changes in behavior:Ultimately, for weight loss to be effective and long-lasting, people must change their behavior. Weight-loss programs that help people change their behavior are the most effective. To change behavior, people need certain skills, such as
- Problem solving
- Stress management
- Self-monitoring
- Contingency management
- Stimulus control
To manage stress, people can learn to identify stressful situations and develop ways to manage the stress that do not involve eating—for example, by going for a walk, meditating, or taking deep breaths.
To monitor themselves, people may keep a food log, including the number of calories in the foods, and weigh themselves regularly. They may record where and when they eat, what their mood is when they eat, and who is with them. With this information, they can observe and record patterns of behavior and eating and may be able to avoid situations that lead to weight gain or unhealthy eating.
Contingency management involves providing rewards (other than food) for behavior that contributes to weight loss or maintenance. For example, if people walk more or eat less of certain foods, they may reward themselves by getting new clothes or going to a movie. Rewards may also come from other people—for example, praise from family members or members of a support group.
To control stimuli that can trigger unhealthy eating, people can learn to identify obstacles to healthy eating and an active lifestyle. Then they can develop strategies to overcome them. For example, people may avoid going by a fast food restaurant on their way to work or not keep sweets in the house. To develop an active lifestyle, they may take up an active hobby (such as gardening), walk more, make a habit of taking the stairs instead of elevators, or park at the far end of parking lots (resulting in a longer walk).
Internet resources, applications for mobile devices, and other technological devices may also help people develop an active lifestyle and maintain weight loss. Applications can help people set a weight-loss goal, monitor their progress, track food consumption, and record physical activity.
Drugs:For people who are obese or overweight and have weight-related disorders, drugs can be useful. Drugs are most effective when used with changes in diet, increased physical activity, and structured programs that include changes in behavior. Some weight-loss drugs are intended to be used for a short time. Others are intended to be used for a long time.
Weight-loss drugs that are currently available include
- Orlistat
- Phentermine
- A combination of phentermine
and topiramate
Orlistat
limits the breakdown and absorption of fats in the intestine, producing, in effect, a low-fat diet. Orlistat
is available over the counter as well as by prescription. It results in unabsorbed fat in the digestive tract. This fat can cause bloating, gas and loose stools, but these problems tend to resolve during the second year of treatment. Orlistat
should be taken with meals. Orlistat
can interfere with the absorption of the fat-soluble vitamins: A, D, E, and K. If not enough vitamin D
is absorbed, some people develop osteoporosis, making fractures more likely. People who take orlistat
should take a vitamin supplement that contains these nutrients. The supplement should be taken at least 2 hours before or after taking orlistat
.
Phentermine
reduces appetite by affecting chemical messengers in the part of the brain that controls appetite. It is available by prescription only and should be taken only for a short time (3 months or less). It can increase blood pressure and heart rate and cause insomnia, anxiety, and constipation.
Phentermine
plus topiramate
(a drug used to treat seizures and migraines) is available by prescription only. This combination results in weight loss for up to 2 years. However, it can cause birth defects, so women of childbearing age should take it only if they are using birth control and are tested monthly for pregnancy. These drugs can cause problems with sleep and concentration and can increase heart rate.
Lorcaserin may be available soon. It is given by prescription only. It suppresses appetite by affecting certain receptors in the brain.
The combination of fenfluramine and phentermine
(often called fen-phen) was the most effective drug treatment. However, fenfluramine was removed from the market because heart valve problems occurred in people who took this combination.
Some over-the-counter diet aids, including medicinal herbs, claim to enhance weight loss by increasing metabolism or by increasing a feeling of fullness. These supplements have not been shown to be effective and may contain harmful additives or stimulants (such as ephedra, caffeine, guarana, and phenylpropanolamine) and should be avoided.
Many new drugs for the treatment of obesity are being developed and will probably change the way obesity is treated in the future.
Spotlight on AgingIn the United States, the percentage of older people who are obese has been increasing. Obesity in older people is a concern because excess weight increases the risk of certain health problems that tend to become more common as people age: diabetes, cancer, abnormal levels of fats (lipids) in the blood (dyslipidemia), high blood pressure, heart failure, coronary artery disease, and joint disorders.
Several age-related changes contribute to gaining weight:
- Decreased physical activity: Some reasons for decreased activity are related to aging. They include retiring, becoming physical unable to exercise, developing disorders that make movement painful (such as arthritis), and having problems with balance. Other factors may also limit physical activity. For example, people may not want to walk because there are no sidewalks, there is too much traffic, or the neighborhood seems unsafe.
- Loss of muscle tissue: Muscle tissue is lost partly because levels of growth hormone and sex hormones (estrogen in women and testosterone in men) decrease. But the main reason older people lose muscle tissue is physical inactivity. The less muscle tissue people have, the fewer calories their body burns when resting and the easier it is to gain weight.
- Increased body fat: When the amount of muscle tissue decreases, the percentage of fat in the body increases. Fat tissue burns fewer calories. Also, the higher percentage of fat means that older people with a normal body mass index (BMI), which is based only on weight and height, may have a higher risk of weight-related health problems than expected. Waist circumference predicts health risks better than BMI in older people.
- Shifting of body fat to the waist: With aging, body fat tends to shift to the waist. Fat that accumulates around the waist and abdomen (as opposed to the hips and thighs) increases the risk of health problems, such as high blood pressure, diabetes, and coronary artery disease.
Older people are at greater risk of undernutrition than younger people. Therefore, when they try to lose weight, they should be sure to consume a healthy and balanced diet.
Weight-loss drugs have not been studied in older people, and risks may outweigh benefits. However, orlistat
may be useful for older people with diabetes or high blood pressure. Weight-loss (bariatric) surgery may be appropriate for older people who are healthy and are functioning well.
`
To visit weight loss the new formula click here