Obesity is an abnormal accumulation of body fat, usually 20% or more over an individual's ideal body weight. Obesity is associated with increased risk of illness, disability, and death.
The branch of medicine that deals with the study and treatment of obesity is known as bariatrics. As obesity has become a major health problem in the United States, bariatrics has become a separate medical and surgical specialty.
Obesity traditionally has been defined as a weight at least 20% above the weight corresponding to the lowest death rate for individuals of a specific height, gender, and age (ideal weight). Twenty to forty percent over ideal weight is considered mildly obese; 40-100% over ideal weight is considered moderately obese; and 100% over ideal weight is considered severely, or morbidly, obese. More recent guidelines for obesity use a measurement called BMI (body mass index) which is the individual's weight multiplied by 703 and then divided by twice the height in inches. BMI of 25.9-29 is considered overweight; BMI over 30 is considered obese. Measurements and comparisons of waist and hip circumference can also provide some information regarding risk factors associated with weight. The higher the ratio, the greater the chance for weight-associated complications. Calipers can be used to measure skin-fold thickness to determine whether tissue is muscle (lean) or adipose tissue (fat).
Much concern has been generated about the increasing incidence of obesity among Americans. Some studies have noted an increase from 12% to 18% occurring between 1991 and 1998. Other studies have actually estimated that a full 50% of all Americans are overweight. The World Health Organization terms obesity a worldwide epidemic, and the diseases which can occur due to obesity are becoming increasingly prevalent.
Excessive weight can result in many serious, potentially life-threatening health problems, including hypertension, Type II diabetes mellitus (non-insulin dependent diabetes), increased risk for coronary disease, increased unexplained heart attack, hyperlipidemia, infertility, and a higher prevalence of colon, prostate, endometrial, and, possibly, breast cancer. Approximately 300,000 deaths a year are attributed to obesity, prompting leaders in public health, such as former Surgeon General C. Everett Koop, M.D., to label obesity "the second leading cause of preventable deaths in the United States."
Causes and symptoms
The mechanism for excessive weight gain is clear—more calories are consumed than the body burns, and the excess calories are stored as fat (adipose) tissue. However, the exact cause is not as clear and likely arises from a complex combination of factors. Genetic factors significantly influence how the body regulates the appetite and the rate at which it turns food into energy (metabolic rate). Studies of adoptees confirm this relationship—the majority of adoptees followed a pattern of weight gain that more closely resembled that of their birth parents than their adoptive parents. A genetic predisposition to weight gain, however, does not automatically mean that a person will be obese. Eating habits and patterns of physical activity also play a significant role in the amount of weight a person gains. Recent studies have indicated that the amount of fat in a person's diet may have a greater impact on weight than the number of calories it contains. Carbohydrates like cereals, breads, fruits, and vegetables and protein (fish, lean meat, turkey breast, skim milk) are converted to fuel almost as soon as they are consumed. Most fat calories are immediately stored in fat cells, which add to the body's weight and girth as they expand and multiply. A sedentary lifestyle, particularly prevalent in affluent societies, such as in the United States, can contribute to weight gain. Psychological factors, such as depression and low self-esteem may, in some cases, also play a role in weight gain.
|Height And Weight Goals|
|Height||Small Frame||Medium Frame||Large Frame|
|5′2″ 5′3″ 5′4″||128-134 lbs. 130-136 132-138||131-141 lbs. 133-143 135-145||138-150 lbs. 140-153 142-153|
|5′5″ 5′6″ 5′7″||134-140 136-142 138-145||137-148 139-151 142-154||144-160 146-164 149-168|
|5′8″ 5′9″ 5′10″||140-148 142-151 144-154||145-157 148-160 151-163||152-172 155-176 158-180|
|5′11″ 6′0″ 6′1″||146-157 159-160 152-164||154-166 157-170 160-174||161-184 164-188 168-192|
|6′2″ 6′3″ 6′4″||155-168 158-172 162-176||164-178 167-182 171-187||172-197 176-202 181-207|
|Height||Small Frame||Medium Frame||Large Frame|
|4′10″ 4′11″ 5′0″||102-111 lbs. 103-113 104-115||109-121 lbs. 111-123 113-126||118-131 lbs. 120-134 112-137|
|5′1″ 5′2″ 5′3″||106-118 108-121 111-124||115-129 118-132 121-135||125-140 128-143 131-147|
|5′4″ 5′5″ 5′6″||114-127 117-130 120-133||124-141 127-141 130-144||137-151 137-155 140-159|
|5′7″ 5′8″ 5′9″||123-136 126-139 129-142||133-147 136-150 139-153||143-163 146-167 149-170|
|5′10″ 5′11″ 6′0″||132-145 135-148 138-151||142-156 145-159 148-162||152-176 155-176 158-179|
At what stage of life a person becomes obese can affect his or her ability to lose weight. In childhood, excess calories are converted into new fat cells (hyperplastic obesity), while excess calories consumed in adulthood only serve to expand existing fat cells (hypertrophic obesity). Since dieting and exercise can only reduce the size of fat cells, not eliminate them, persons who were obese as children can have great difficulty losing weight, since they may have up to five times as many fat cells as someone who became overweight as an adult.
Obesity can also be a side effect of certain disorders and conditions, including:
- Cushing's syndrome, a disorder involving the excessive release of the hormone cortisol
- hypothyroidism, a condition caused by an underactive thyroid gland
- neurologic disturbances, such as damage to the hypothalamus, a structure located deep within the brain that helps regulate appetite
- consumption of such drugs as steroids, antipsychotic medications, or antidepressants
The major symptoms of obesity are excessive weight gain and the presence of large amounts of fatty tissue. Obesity can also give rise to several secondary conditions, including:
- arthritis and other orthopedic problems, such as lower back pain
- adult-onset asthma
- gum disease
- high cholesterol levels
- high blood pressure
- menstrual irregularities or cessation of menstruation (amenorhhea)
- decreased fertility, and pregnancy complications
- shortness of breath that can be incapacitating
- sleep apnea and sleeping disorders
- skin disorders arising from the bacterial breakdown of sweat and cellular material in thick folds of skin or from increased friction between folds
- emotional and social problems
Diagnosis of obesity is made by observation and by comparing the patient's weight to ideal weight charts. Many doctors and obesity researchers refer to the body mass index (BMI), which uses a height-weight relationship to calculate an individual's ideal weight and personal risk of developing obesity-related health problems. Physicians may also obtain direct measurements of an individual's body fat content by using calipers to measure skin-fold thickness at the back of the upper arm and other sites. The most accurate means of measuring body fat content involves immersing a person in water and measuring relative displacement; however, this method is very impractical and is usually only used in scientific studies requiring very specific assessments. Women whose body fat exceeds 30% and men whose body fat exceeds 25% are generally considered obese.
Doctors may also note how a person carries excess weight on his or her body. Studies have shown that this factor may indicate whether or not an individual has a predisposition to develop certain diseases or conditions that may accompany obesity. "Apple-shaped" individuals who store most of their weight around the waist and abdomen are at greater risk for cancer, heart disease, stroke, and diabetes than "pear-shaped" people whose extra pounds settle primarily in their hips and thighs.
Treatment of obesity depends primarily on how overweight a person is and his or her overall health. However, to be successful, any treatment must affect life-long behavioral changes rather than short-term weight loss. "Yo-yo" dieting, in which weight is repeatedly lost and regained, has been shown to increase a person's likelihood of developing fatal health problems than if the weight had been lost gradually or not lost at all. Behavior-focused treatment should concentrate on:
- What and how much a person eats. This aspect may involve keeping a food diary and developing a better understanding of the nutritional value and fat content of foods. It may also involve changing grocery-shopping habits (e.g., buying only what is on a prepared list and only going on a certain day), timing of meals (to prevent feelings of hunger, a person may plan frequent, small meals), and actually slowing down the rate at which a person eats.
- How a person responds to food. This may involve understanding what psychological issues underlie a person's eating habits. For example, one person may binge eat when under stress, while another may always use food as a reward. In recognizing these psychological triggers, an individual can develop alternate coping mechanisms that do not focus on food.
- How they spend their time. Making activity and exercise an integrated part of everyday life is a key to achieving and maintaining weight loss. Starting slowly and building endurance keeps individuals from becoming discouraged. Varying routines and trying new activities also keeps interest high.
For most individuals who are mildly obese, these behavior modifications entail life-style changes they can make independently while being supervised by a family physician. Other mildly obese persons may seek the help of a commercial weight-loss program (e.g., Weight Watchers). The effectiveness of these programs is difficult to assess, since programs vary widely, drop-out rates are high, and few employ members of the medical community. However, programs that emphasize realistic goals, gradual progress, sensible eating, and exercise can be very helpful and are recommended by many doctors. Programs that promise instant weight loss or feature severely restricted diets are not effective and, in some cases, can be dangerous.
For individuals who are moderately obese, medically supervised behavior modification and weight loss are required. While doctors will put most moderately obese patients on a balanced, low-calorie diet (1200-1500 calories a day), they may recommend that certain individuals follow a very-low-calorie liquid protein diet (400-700 calories) for as long as three months. This therapy, however, should not be confused with commercial liquid protein diets or commercial weight-loss shakes and drinks. Doctors tailor these diets to specific patients, monitor patients carefully, and use them for only a short period of time. In addition to reducing the amount and type of calories consumed by the patient, doctors will recommend professional therapists or psychiatrists who can help the individual effectively change his or her behavior in regard to eating.
For individuals who are severely obese, dietary changes and behavior modification may be accompanied by surgery to reduce or bypass portions of the stomach or small intestine. Although obesity surgery is less risky as of 2003 because of recent innovations in equipment and surgical technique, it is still performed only on patients for whom other strategies have failed and whose obesity seriously threatens their health. Other surgical procedures are not recommended, including liposuction, a purely cosmetic procedure in which a suction device is used to remove fat from beneath the skin, and jaw wiring, which can damage gums and teeth and cause painful muscle spasms.
(Illustration by Argosy Inc.)
Other weight-loss medications available with a doctor's prescription include:
- diethylpropion (Tenuate, Tenuate dospan)
- mazindol (Mazanor, Sanorex)
- phendimetrazine (Bontril, Plegine, Prelu-2, X-Trozine)
- phentermine (Adipex-P, Fastin, Ionamin, Oby-trim)
Phenylpropanolamine (Acutrim, Dextarim) is the only nonprescription weight-loss drug approved by the FDA These over-the-counter diet aids can boost weight loss by 5%. Combined with diet and exercise and used only with a doctor's approval, prescription anti-obesity medications enable some patients to lose 10% more weight than they otherwise would. Most patients regain lost weight after discontinuing use of either prescription medications or nonprescription weight-loss products.
Prescription medications or over-the-counter weight-loss products can cause:
- dry mouth
None of them should be used by patients taking monoamine oxidase inhibitors (MAO inhibitors).
Doctors sometimes prescribe fluoxetine (Prozac), an antidepressant that can increase weight loss by about 10%. Weight loss may be temporary and side effects of this medication include diarrhea, fatigue, insomnia, nausea, and thirst. Weight-loss drugs currently being developed or tested include ones that can prevent fat absorption or digestion; reduce the desire for food and prompt the body to burn calories more quickly; and regulate the activity of substances that control eating habits and stimulate overeating.
The Chinese herb ephedra (Ephedra sinica), combined with caffeine, exercise, and a low-fat diet in physician-supervised weight-loss programs, can cause at least a temporary increase in weight loss. However, the large doses of ephedra required to achieve the desired result can also cause:
- heart arrhythmias
- heart attack
- high blood pressure
Ephedra should not be used by anyone with a history of diabetes, heart disease, or thyroid problems. In fact, an article that appeared in the Journal of the American Medical Association in early 2003 advised against the use of ephedra.
Diuretic herbs, which increase urine production, can cause short-term weight loss but cannot help patients achieve lasting weight control. The body responds to heightened urine output by increasing thirst to replace lost fluids, and patients who use diuretics for an extended period of time eventually start retaining water again anyway. In moderate doses, psyllium, a mucilaginous herb available in bulk-forming laxatives like Metamucil, absorbs fluid and makes patients feel as if they have eaten enough. Red peppers and mustard help patients lose weight more quickly by accelerating the metabolic rate. They also make people more thirsty, so they crave water instead of food. Walnuts contain serotonin, the brain chemical that tells the body it has eaten enough. Dandelion (Taraxacum officinale) can raise metabolism and counter a desire for sugary foods.
Acupressure and acupuncture can also suppress food cravings. Visualization and meditation can create and reinforce a positive self-image that enhances the patient's determination to lose weight. By improving physical strength, mental concentration, and emotional serenity, yoga can provide the same benefits. Also, patients who play soft, slow music during meals often find that they eat less food but enjoy it more.
Getting the correct ratios of protein, carbohydrates, and good-quality fats can help in weight loss via enhancement of the metabolism. Support groups that are informed about healthy, nutritious, and balanced diets can offer an individual the support he or she needs to maintain this type of eating regimen.
As many as 85% of dieters who do not exercise on a regular basis regain their lost weight within two years. In five years, the figure rises to 90%. Repeatedly losing and regaining weight (yo yo dieting) encourages the body to store fat and may increase a patient's risk of developing heart disease. The primary factor in achieving and maintaining weight loss is a life-long commitment to regular exercise and sensible eating habits.
Obesity experts suggest that a key to preventing excess weight gain is monitoring fat consumption rather than counting calories, and the National Cholesterol Education Program maintains that only 30% of calories should be derived from fat. Only one-third of those calories should be contained in saturated fats (the kind of fat found in high concentrations in meat, poultry, and dairy products). Because most people eat more than they think they do, keeping a detailed food diary is a useful way to assess eating habits. Eating three balanced, moderate-portion meals a day—with the main meal at mid-day—is a more effective way to prevent obesity than fasting or crash diets. Exercise increases the metabolic rate by creating muscle, which burns more calories than fat. When regular exercise is combined with regular, healthful meals, calories continue to burn at an accelerated rate for several hours. Finally, encouraging healthful habits in children is a key to preventing childhood obesity and the health problems that follow in adulthood.
New directions in obesity treatment
The rapid rise in the incidence of obesity in the United States since 1990 has prompted researchers to look for new treatments. One approach involves the application of antidiabetes drugs to the treatment of obesity. Metformin (Glucophage), a drug that was approved by the Food and Dug Administration (FDA) in 1994 for the treatment of type 2 diabetes, shows promise in treating obesity associated with insulin resistance.
Another field of obesity research is the study of hormones, particularly leptin, which is produced by fat cells in the body, and ghrelin, which is secreted by cells in the lining of the stomach. Both hormones are known to affect appetite and the body's energy balance. Leptin is also related to reproductive function, while ghrelin stimulates the pituitary gland to release growth hormone. Further studies of these two hormones may lead to the development of new medications to control appetite and food intake.
Adipose tissue — Fat tissue.
Appetite suppressant — Drug that decreases feelings of hunger. Most work by increasing levels of serotonin or catecholamine, chemicals in the brain that control appetite.
Bariatrics — The branch of medicine that deals with the prevention and treatment of obesity and related disorders.
Ghrelin — A recently discovered peptide hormone secreted by cells in the lining of the stomach. Ghrelin is important in appetite regulation and maintaining the body's energy balance.
Hyperlipidemia — Abnormally high levels of lipids in blood plasma.
Hyperplastic obesity — Excessive weight gain in childhood, characterized by the creation of new fat cells.
Hypertension — High blood pressure.
Hypertrophic obesity — Excessive weight gain in adulthood, characterized by expansion of already existing fat cells.
Ideal weight — Weight corresponding to the lowest death rate for individuals of a specific height, gender, and age.
Leptin — A protein hormone that affects feeding behavior and hunger in humans. At present it is thought that obesity in humans may result in part from insensitivity to leptin.
A third approach to obesity treatment involves research into the social factors that encourage or reinforce weight gain in humans. Researchers are looking at such issues as the advertising and marketing of food products; media stereotypes of obesity; the development of eating disorders in adolescents and adults; and similar questions.
Beers, Mark H., MD, and Robert Berkow, MD, editors. "Nutritional Disorders: Obesity." Section 1, Chapter 5. In The Merck Manual of Diagnosis and Therapy. Whitehouse Station, NJ: Merck Research Laboratories, 2004.
Flancbaum, Louis, MD, with Erica Manfred and Deborah Biskin. The Doctor's Guide to Weight Loss Surgery. West Hurley, NY: Fredonia Communications, 2001.
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Shekelle, P. G., M. L. Hardy, S. C. Morton, et al. "Efficacy and Safety of Ephedra and Ephedrine for Weight Loss and Athletic Performance: A Meta-Analysis." Journal of the American Medical Association 289 (March 26, 2003): 1537-1545.
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American Dietetic Association. (800) 877-1600. www.eatright.org..
American Obesity Association (AOA). 1250 24th Street NW, Suite 300, Washington, DC 20037. (202) 776-7711 or (800) 98-OBESE. www.obesity.org.
American Society for Bariatric Surgery. 7328 West University Avenue, Suite F, Gainesville, FL 32607. (352) 331-4900. www.asbs.org.
American Society of Bariatric Physicians. 5453 East Evans Place, Denver, CO 80222-5234. (303) 770-2526. www.asbp.org.
HCF Nutrition Research Foundation, Inc. P.O. Box 22124, Lexington, KY 40522. (606) 276-3119.
National Institute of Diabetes and Digestive and Kidney Diseases. 31 Center Drive, USC2560, Building 31, Room 9A-04, Bethesda, MD 20892-2560. (301) 496-3583. 〈www.niddk.nih/gov〉.
National Obesity Research Foundation. Temple University, Weiss Hall 867, Philadelphia, PA 19122.
Weight-Control Information Network. 1 Win Way, Bethesda, MD 20896-3665. (301) 951-1120. 〈www.navigator.tufts.edu/special/win.html〉.
An excess of subcutaneous fat in proportion to lean body mass. Excess fat accumulation is associated with increase in the size (hypertrophy) as well as the number (hyperplasia) of adipose tissue cells. Obesity is variously defined in terms of absolute weight, weight:height ratio, distribution of subcutaneous fat, and societal and esthetic norms. Measures of weight in proportion to height include relative weight (RW, body weight divided by median desirable weight for a person of the same height and medium frame according to actuarial tables), body mass index (BMI, kg/m2) and ponderal index (kg/m3). These do not differentiate between excess adiposity and increased lean body mass. In contrast, subscapular and triceps skinfold measurements and determination of the waist:hip ratio help define the regional deposition of fat and differentiate the more medically significant central obesity from peripheral obesity in adults. No single cause can explain all cases of obesity. Ultimately it results from an imbalance between energy intake and energy expenditure. Although faulty eating habits related to failure of normal satiety feedback mechanisms may be responsible for some cases, many obese people neither consume more calories nor eat different proportions of foodstuffs than nonobese persons. Contrary to popular belief, obesity is not caused by disorders of pituitary, thyroid, or adrenal gland metabolism. However, it is often associated with hyperinsulinism and relative insulin resistance. Studies of obese twins strongly suggest the presence of genetic influences on resting metabolic rate, feeding behavior, changes in energy expenditures in response to overfeeding, lipoprotein lipase activity, and basal rate of lipolysis. Environmental factors associated with obesity include socioeconomic status, race, region of residence, season, urban living, and being part of a smaller family. The prevalence of obesity is greater when weight is measured during winter rather than summer. Obesity is much more common in the southeastern U.S., although the northeastern and midwestern states also have high rates, a phenomenon independent of race, population density, and season.
Synonym(s): adiposity (1) , corpulence, corpulency
[L. obesus, pp. of obedo, to eat up, + -ity]
Obesity is a major public health problem and the leading nutritional disorder in the U.S. It is responsible for more than 280,000 deaths annually in this country. A widely accepted definition of obesity is body weight that is 20% or more in excess of ideal weight:height ratio according to actuarial tables. By this definition, 34% of adults in the U.S. are obese. The National Institutes of Health have defined obesity as a BMI of 30 kg/m2 or more, and overweight as a BMI between 25 and 30 kg/m2. By these criteria, two thirds of adults are either overweight or obese. There is strong evidence that the prevalence of obesity is increasing in both children and adults. Increases are particularly striking among African-Americans and Mexican-Americans. More than 80% of black women over the age of 40 are overweight, and 50% are obese. Among factors blamed for the steady increase in the prevalence of obesity are unhealthful eating practices (high-fat diet, overlarge portions) and the decline in physical activity associated with use of automobiles and public transportation instead of walking, labor-saving devices including computers, and passive forms of entertainment and recreation (television, computer games). Despite efforts of public health authorities to educate the public about the dangers of obesity, it is widely viewed as a cosmetic rather than a medical problem. Obesity is an independent risk factor for hypertension, hypercholesterolemia, Type 2 diabetes mellitus, myocardial infarction, certain malignancies (cancer of the colon, rectum, and prostate in men and of the breast, cervix, endometrium, and ovary in women), obstructive sleep apnea, hypoventilation syndrome, osteoarthritis and other orthopedic disorders, infertility, lower extremity venous stasis disease, gastroesophageal reflux disease, and urinary stress incontinence. Lesser degrees of obesity can constitute a significant health hazard in the presence of diabetes mellitus, hypertension, heart disease, or their associated risk factors. Body fat distribution in central (abdominal or male pattern, with an increased waist:hip ratio) versus peripheral (gluteal or female pattern) adipose tissue depots is associated with higher risks of many of these disorders. Obese people are more liable to injury, more difficult to examine by palpation and imaging techniques, and more likely to have unsuccessful outcomes and complications from surgical operations. Not least among the adverse effects of obesity are social stigmatization, poor self-image, and psychological stress. Weight reduction is associated with improvement in most of the health risks of obesity. All treatments for obesity (other than cosmetic surgical procedures in which subcutaneous fat is mechanically removed) require creation of an energy deficit by reducing caloric intake, increasing physical exercise, or both. Basic weight reduction programs involve consumption of a restricted-calorie, low-fat diet and performance of at least 30 minutes of endurance-type physical activity of at least moderate intensity on most and preferably all days of the week. Behavior modification therapy, hypnosis, anorexiant drugs (sympathomimetic agents, sibutramine), the lipase inhibitor orlistat, and surgical procedures to reduce gastric capacity or intestinal absorption of nutrients are useful in selected cases, but the emphasis should be on establishing permanent changes in lifestyle. Weight reduction is not recommended during pregnancy or in patients with osteoporosis, cholelithiasis, severe mental illness including anorexia nervosa, or terminal illness.
Since the World Health Organization declared a global obesity epidemic in 1997, weight has played a dominant role in the conversation about health and wellness. At the intersection of physical and mental health, influenced by a heady mix of public health, sociology, economics and culture, the increase in average weight through the 21st century is a topic of passionate debate. The crux of the argument usually comes down to one fundamental question: is it possible to be fit and fat? We know that normal weight is by no means a guarantee of wellbeing, but is excess fat an absolute sign of poor health?
The media has entered the fray. In 2015 alone, the Huffington Post declared: ‘Yes, it’s possible to be obese and healthy (sort of).’ Forbes told us that healthy obesity ‘is mainly a myth’. Salon asserted that healthy obesity might not exist at all, while Slate countered: ‘It’s time to stop telling fat people to become thin.’
On one side of the conversation stands most of the medical community, emphasising that obesity is inherently unhealthy, and that managing weight is key to health. On the other are proponents of the Health at Every Size and fat-acceptance movements, who claim that obesity is not a major concern; they argue instead that health is independent of body weight, and that the ‘war on obesity’ may be more damaging than obesity itself. Further clouding the debate on whether obesity can be healthy is the recently identified ‘obesity paradox’ – the idea that obesity may actually be protective in some circumstances or populations, for instance, among the elderly or those with chronic disease.
The two sides seem to agree on only one set of facts: after decades of steady increase, the overall prevalence of obesity in the United States finally held steady between 2004 and 2012 at 35 per cent; body weight in the US today is higher than at any time in the past, but the relentless increase has at least come screeching to a halt. These facts are based on a value called the body-mass index, or BMI – derived from weight divided by height squared in metric units. BMI is a centuries-old epidemiological tool designed to assess obesity rates at the level of a population. But because it is a quick and easy way to assess a healthy body state, it was adopted as a standard diagnostic tool for individual patients. It does not consider distribution of fat, type of fat, muscle tone, age, sex, or even big bones. In spite of these flaws, healthcare professionals continue to use BMI as a guideline. A BMI of 20-25 is considered ‘normal’, and anyone larger or smaller is automatically counselled to achieve a healthier weight.
In 2009, the Lancet reported that mortality increased about 30 per cent for every five-point increase in BMI above the normal range. In their interpretation of the data, the study authors estimated that obese individuals with a BMI between 30 and 35 would see median survival reduced by 2-4 years; at a BMI of 40-45, median survival is reduced by 8-10 years. Obesity is generally understood as a risk factor for heart disease, stroke, cancer, and diabetes, as well as an increase in overall mortality. Excess body weight also increases stress on joints and internal organs.
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Given these concerns, it’s easy to understand why so many people have celebrated the plateau in BMI. Unfortunately, that news has buried the lead: BMI may not be the best measure of obesity.
Your percentage of body fat and waist or abdominal circumference are far more reliable personal indicators of health outcomes than BMI. For example, central obesity, measured by waist circumference, is a more accurate determinant of personal risk and shows an even stronger correlation with poor health outcomes. Also known as visceral obesity, it is considered more dangerous than peripheral obesity (that is, in the extremities) because it indicates that the extra adipose tissue is surrounding your vital organs – practically applied, this means that a thin person with a beer gut may have far more dangerous health risks than a fit person with a high BMI. And while it is true that the average BMI in the US has remained constant at 28.8, both waist size and abdominal obesity have actually continued to increase. According to the Centers for Disease Control and Prevention, the average waist size for American women and men is currently 37.5 and 39.5, respectively.
But all of this is relevant only if you accept obesity as a legitimate health concern. Those who argue against this idea point to the Metabolically Healthy Obese (MHO) – patients who have excess weight but whose biomarkers seem to indicate the health of an individual of ideal weight. Some have argued that if an obese individual is negative for the known metabolic risks associated with increased mortality – hypertension, high fasting blood sugar, low levels of HDL (good) cholesterol and high levels of triglyceride fats in the bloodstream – then life expectancy should be the same as a normal-weight counterpart. If you can be healthy and obese, the argument goes, we should stop harping about weight altogether.
It is a tantalising hypothesis, but what does the evidence show? To find out, Australian researchers followed a group of metabolically healthy obese participants over the course of five to 10 years. Despite initially normal biomarkers, the team reported in a 2013 issue of Diabetes Care that their subjects were more likely than non-obese control patients to develop metabolic abnormalities and diabetes. One-third of the participants who began the study as metabolically-healthy obese had become ‘unhealthy’ obese by the time the study ended. Younger people and those with low central obesity (indicated by a smaller abdominal circumference) were more likely to sustain metabolically-healthy obesity over time. But for a significant percentage of participants in the study, ‘healthy obesity’ was a transient state, a precursor to the development of medical abnormalities.
Some studies indicate that the metabolically-healthy obese have no increased risk of mortality, but these have tended to follow subjects for less than a decade. Contrast that with an article published in 2015 in the Journal of the American College of Cardiology addressing the course of metabolically-healthy obesity over two decades. Researchers found that after 20 years, roughly half of those who were initially metabolically-healthy obese adults had become unhealthy obese. The lead author, Joshua Bell, explains: ‘Even obese adults who appear to be metabolically healthy have a substantially greater risk for developing type 2 diabetes and cardiovascular disease compared with healthy, normal-weight adults. There is also a strong tendency for healthy obese adults to progress to unhealthy obesity (the highest risk group) over time. Excess fat is itself a metabolic dysfunction, with strong links to insulin resistance. Some obese adults may have a more favourable fat distribution and are considered relatively healthy, but the number of obese adults who can maintain an optimal balance of fat stores in the long-term is not high.’
Americans seem to have access to a Weight Watchers in every town centre and face a steady slew of Jenny Craig ads on TV
Others argue that we may even be using the wrong metabolic lab ranges for the healthy obese. A 2014 study in the Journal of the American College of Cardiology lowered the diagnostic bar by looking specifically at coronary artery calcification in asymptomatic and metabolically-normal individuals of all weights. Obese participants had higher rates of subclinical coronary artery disease than their normal-weight counterparts. By relying on the same normal ranges for obese and normal-weight individuals, we may be missing early signs of disease.
It is undeniable that healthy obesity is far better for you than unhealthy obesity. The ‘healthy’ obese live longer, get sick less often, and are more physically active than their unhealthy-obese counterparts. No one disputes that it is better for you to have low blood pressure and normal blood glucose levels; the question, fundamentally, is whether obese individuals with normal lab values are as healthy as normal-weight individuals with comparable values. The answer, at least according to the majority of biomedical research, is that they are not.
And even if the metabolically-healthy obese had the same quality and quantity of life as their normal weight counterparts, they account for a minority of obese patients. The same can be said of the obese elderly and chronically ill who benefit from the ‘obesity paradox’, in which extra weight may be protective. These individuals are anomalies. Public health cannot be framed around the outliers; rather, the focus must be on the majority. And the truth is that for the majority of obese individuals, excess body mass is a costly health concern.
The high price of obesity goes well beyond personal health. As rates of obesity climb, so does health care spending. By some estimates, 20 per cent of health care costs in the United States are attributed to obesity. A recent study by the Brookings Institution in Washington, DC, suggested that the societal cost of obesity could add up to trillions.
In the face of the growing epidemic, the medical establishment and a bankable diet industry have jumped on to the weight-loss bandwagon. Americans seem to have access to a Weight Watchers in every town centre and face a steady slew of Jenny Craig ads on TV, yet the problem remains entrenched.
On the surface, the solution appears simple: health care professionals could just tell people to eat less and exercise more; stop buying McDonald’s and cook some vegetables. Get away from the television and go for a run outside. Have one potato chip instead of five.
These are obvious (and, in some circumstances, valid) recommendations. Unless obesity is secondary to another medical issue, reducing calorie intake and increasing calorie expenditure should lead to weight loss — that arithmetic is simple and verifiable.
Some in the Health at Every Size movement argue that weight is not a modifiable factor, and that we should no longer consider it changeable
But these suggestions are easier said than done. A recent study published in the American Journal of Public Health tracked the weight of more than 270,000 adult men and women between 2004 and 2014. Researchers found that only 0.5 per cent of obese men and 0.8 per cent of obese women were able to attain and maintain a normal body weight. They concluded that once an individual becomes obese, it is very difficult to return to a healthy body weight. Indeed, persistent dieters stuck in a pattern of weight cycling, or ‘yo-yo dieting’, might be altering their hormones and altering their sense of hunger, some research suggests.
Furthermore, even if weight loss works, it is important to consider what kind of weight an individual is losing: fat loss decreases mortality but loss of lean muscle weight may have the opposite effect. And how is that weight being lost? A person could technically lose weight on a steady diet of pizza and french fries, but this would do little to improve overall health.
Citing the myriad studies suggesting that weight loss is often unsustainable or meaningless, some in the Health at Every Size movement argue that weight is not a modifiable factor, and that we should no longer consider it changeable. More reasonably, what it means is that we have no real way of managing weight yet, not that our BMI is part of our manifest destiny. Nevertheless, given these known challenges, and in light of the cultural and psychological issues at play, some question whether weight should be a part of the health conversation at all.
Americans are raising a generation of adults who have been overweight and obese since childhood. They carry with them not only the physical effects of obesity but, for some, a lifetime of discrimination and abuse related to their weight. And there is no apparent end in sight. The California psychologist Deb Burgard, an expert in the treatment of eating disorders, argues that the major health risk for the obese comes not from excess adipose tissue but from the treatment that the overweight often receive – emotional abuse, delivered by everyone, from well-meaning friends and family, to doctors and strangers on the street.
Our cultural response to obesity is the spectacular failure of body-shaming and stigmatising weight, a cruel and dehumanising attitude that reduces people to their body size. To the people who shame others under the guise of helping: if fat-shaming children or stigmatising overweight adults worked, the prevalence of obesity would have dropped years ago. Issues of health are between patients and health care providers. Weight discrimination does not serve to increase weight loss or shame people into thinness, and may, in fact, cause people to gain more weight. Any programme focused on healthy behaviours and weight must emphasise the importance of loving and respecting the body you have.
‘So we have to ask: is there value in focusing on weight at all?’ Burgard said. ‘Even if the data show a disparity between the health of people at a higher and lower weight, why do we define this as a risk factor located in the body – rather than evidence of a health disparity due to weight bias, economic inequality, racism, lack of access to competent health care, etc?’
She speaks with a conviction and passion that come from years of experience working with individuals who are often silenced and judged only on the basis of their appearance. Her point sticks, blunted by data that do, in fact, show a health disparity between people of different weights – and on the other hand, strengthened by research showing a strong connection between chronic stress and health.
So I reach for middle ground. Can we both be right? Can’t we recognise obesity simultaneously as a risk factor located in the body and a magnet for social stress? Obesity is more prevalent in minority populations, those of low socioeconomic status, and other vulnerable groups. These vulnerabilities reflect the fact that, for many, obesity comes down to lifestyle and surroundings. People who live close to a supermarket that sells fresh foods (and have the space and time to prepare it) are more likely to have a normal BMI; proximity to convenience stores has the opposite effect. People who live in ‘walkable’ neighbourhoods with accessible, well-maintained sidewalks have lower BMIs and rates of obesity. Living next to a highway or on a street without a sidewalk is associated with increased levels of obesity. Access to a safe outside space increases physical activity. These are very basic ideas – it’s not rocket science.
Diet and exercise will both play a role in the fight against obesity, though people keep debating which matters more. In March of this year, there was an enormous amount of coverage given to an editorial in the British Journal of Sports Medicine that declared: ‘You cannot outrun a bad diet.’ The authors placed the blame for the obesity epidemic squarely on the shoulders of the food industry and unhealthy diets. The article was temporarily retracted before being reissued with a stated conflict of interest; the authors had declined to acknowledge that they were both involved in the diet industry. But that does not mean it was entirely wrong. A bad diet – high in salt, trans fats and sugar — cannot be outrun, no matter what Coca Cola wants you to believe. Although it is possible to maintain a healthy weight on a high-fat diet, society’s tendency to ‘super-size’ constantly challenges such restraint. And even if you could keep serving size down, being thin doesn’t exempt you from the effects of poor nutrition.
You can be thin and still have the same health risks as someone who is obese
A healthy diet may not make up for a lack of physical activity, either. A 2012 study in Obesity found that high levels of cardiorespiratory fitness can help counteract some of the dangerous effects of increased adiposity, thereby decreasing cancer mortality. Increased physical activity is also associated with improved quality of life, independent of weight and body size. The obesity epidemic in the US can be blamed on both Americans’ relatively sedentary lives and their unhealthy diets. No need to pick just one.
‘I’m not sure why the question always focuses on whether obesity is sustainable or not, when the real issue should be: “This is where we’re at now. How can we promote health for everybody?”’ says Harriet Brown, an associate journalism professor at Syracuse University in New York State and the author of Body of Truth, a book about our cultural obsession with weight. ‘Even if you could show in theory that it’s not healthy to be obese in the long term, it still doesn’t mean that getting thin is the solution to everything.’
She is absolutely correct. Getting thin isn’t a panacea. In fact, you can be thin and still have the same health risks as someone who is obese. People who fall into this category eat unhealthily, fail to exercise, and have abnormal lab values, but are blessed with a fast metabolism or helpful genetics, and effortlessly maintain an optimal BMI. The ‘thin obese’ – metabolically-abnormal but optimal-weight individuals – are seldom involved in the discussion, but they should be. Thin people can be unhealthy too, but that doesn’t mean we should ignore weight.
Somewhere along the line, someone made the decision to wage our health war on fat. This was an unfortunate choice because, in reality, health is not only about size – it’s about nutrition and physical activity. The term ‘obesity epidemic’ is ubiquitous and certainly makes for a catchier headline than ‘a high prevalence of unhealthy behaviours associated with an increased national body mass index’, but it misses a key point in our discussion about health. There is an epidemic of unhealthy behaviours, and an elevated BMI is simply the most obvious marker.
The scientific research largely supports the medical community’s perspective – healthy obesity is unlikely to be maintained long-term and excess adipose tissue contributes to many dangerous medical conditions. The history of the obesity epidemic, however, lends some support to the challengers: the current war on obesity – which frequently focuses on weight loss as treatment – is a failed effort.
the psychological impacts of discrimination are profound, but professionals cannot deny a major medical issue because society is cruel
The solution is not to reframe obesity as superfluous, but rather to seek a new approach to a decades-old problem. We need to focus on treating and preventing obesity, not only through intensive weight-loss regimes for individuals, but by attacking the root cause: the behaviours that are damaging to your health, no matter what your size.
Deb Burgard cautions against what she calls the ‘harmful paradigm’ that obesity is a health condition. We are ‘sending people down a road pursuing weight loss when it is very likely to fail and is emotionally abusive’, and when ‘the person will have to experience weight regain’, she says. ‘Weight gain is our body healing from that insult of an unnatural catabolic state.’
I counter that, just because we do not have an effective way of maintaining long-term weight loss, does not mean we should pretend it is not a health goal. Ignoring obesity as a health risk is irresponsible – the psychological impacts of fat shaming and discrimination are profound, but health care professionals cannot deny a major medical issue because society is cruel.
Recent findings suggest that more than one-third of obese Britons classify themselves as merely ‘overweight’. It helps no one – not the doctors, nor the patients, nor their families – when we allow people to delude themselves, and to redefine the relationship between weight and health. We may have reached a new normal, but that doesn’t change the optimum. On the other hand, reducing all of health to a mathematical formula of ‘weight over height squared’ is absurd.
So where does that leave us? As a culture, we must embrace different body types and accept that a person’s weight and waist circumference are not a commentary on their worth. Governments and societies must address the social deficits that contribute to obesity – poverty, food deserts (districts with no ready access to fresh, healthy and affordable food) and lack of exercise spaces – to empower people to take care of their own health. In the long run, the medical community must find ways to help people stay healthy through lifestyle fixes, medical interventions, or both, regardless of their size.
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is a doctor with a masters in public health and a professional focus on low-resource settings. She writes frequently about issues at the crossroads of culture and health.