Body weight is most commonly measured in kilograms or pounds. Body mass index (BMI) is a frequently used measure and serves as an index of weight-for-height calculated in kg/m2. BMI is often used to stratify individuals into categories ranging from underweight to severely obese. One critique of BMI is that it does not distinguish between muscle and fat mass (Kraemer et al. 1990). Anthropomorphic measures (e.g., waist circumference) enhance measurement accuracy by examining distribution of excess weight around the abdominal region. Negative health consequences are associated with a waist circumference > 102 centimeters for men and > 88 centimeters for women (NIH 1998). Total body fat percentage is also used to measure excess weight and can be calculated by skin-fold caliper, hydrostatic weighing, or bioelectrical impedance testing.
Statistics compiled by the Centers for Disease Control and Prevention (CDC) indicate that in 2006 two-thirds of adults in the United States were overweight and 32.2 percent met the criteria for obesity. Moreover, obesity prevalence rates among children and adolescents have tripled since the mid-1980s (Ogden et al. 2003). Average BMI is increasing across demographic groups, and recent reports suggest that 45 percent of non-Hispanic black adults and 30 percent of non-Hispanic white adults are obese (CDC 2006). These trends are alarming because obesity is the second leading cause of preventable death and a risk factor for chronic illness, including type 2 diabetes, hypertension, and coronary heart disease.
Although the causes of obesity are not fully understood, it is viewed as a chronic disease influenced by genetic, environmental, behavioral, and cultural factors. Research suggests that genetic influences account for a significant amount of variability in BMI. Findings from twin studies suggest that up to 70 percent of variation in BMI can be accounted for by genetic factors, while adoption studies have produced more conservative heritability estimates of 20 to 30 percent (Bouchard 2002). However, genetic influences do not account for the dramatic and steady increase in the prevalence of obesity (Brownell 1994). Environmental factors, such as the widespread availability of calorie-dense foods and urban development not conducive to physical activity (e.g., lack of parks and busy intersections), also have contributed significantly to the rise in obesity.
A thin physique continues to be the accepted ideal in Western cultures despite a steady increase in the prevalence of overweight and obesity. Fashion models and popular cultural icons have become increasingly thin since the 1960s (Wolf 1991). Dissatisfaction with body weight has become the norm, especially for women (Rodin et al. 1985). In fact research suggests that 52 percent of men and 66 percent of women in the United States are dissatisfied with their weight (Garner 1997), and some women report dieting even when their weight is at or below normal (Rodin et al. 1985). However, there are racial differences on satisfaction with weight (Gluck and Geliebter 2002). Relative to white females, African American females report less concern about dieting and fatness (Rucker and Cash 1992). In addition, compared to overweight white females, overweight African American females are more satisfied with their bodies and feel more attractive (Stevens et al. 1994). While the overwhelming majority of women desire to lose weight, it is somewhat different for males. Although a substantial percentage (88%) of men who are dissatisfied with their weight do desire to lose weight, 22 percent of men who express dissatisfaction with their bodies actually wish to gain weight (Garner 1997). This is most likely due to the muscular ideals that are portrayed for male physiques (Drewnowski and Yee 1987; Frederick et al. 2005).
Weight-related stigmatization is prevalent in Western cultures, and data suggest that there has been an increase in weight bias since the mid-twentieth century (Latner and Stunkard 2003). Of the many conditions that are stigmatized in Western culture, it has been suggested that the stigma associated with being overweight may be the most debilitating and harmful (Sarlio-Lahteenkorva et al. 1995). Overweight individuals perceive stigmatization from co-workers, strangers, friends, and spouses (Friedman et al. 2005). Obesity also negatively affects employment (Rothblum et al. 1990) and socioeconomic status (Puhl and Brownell 2001). In addition data suggest that weight-based stigmatization negatively impacts the mental health of obese individuals (Friedman et al. 2005) and may contribute to overeating behaviors (Ashmore et al. 2007).
Studies examining obesity and mental health have yielded mixed results. Earlier studies reported no significant mental health differences between community samples of obese and healthy-weight individuals (Wadden and Stunkard 1985). More recently, data from the National Health and Nutrition Examination Survey revealed a 1.5-fold higher risk for major depression among obese individuals relative to healthy-weight cohorts. Results suggested that severely obese individuals were at greatest risk for depression (Onyike et al. 2003). Several reviews suggest that the risk for major depression is particularly significant among the severely obese and those seeking surgical treatment for weight loss (see Wadden and Sarwer 2006), suggesting that extreme obesity is related to increased depression.
Management of obesity is a major health-care challenge. There is a range of available treatments, including lifestyle modification, pharmacotherapy, and bariatric surgery. Typically, a step-care approach is taken with the least invasive intervention attempted first. Most treatments produce some initial weight loss; however, behavioral and pharmacological interventions have been largely unsuccessful in the long-term maintenance of weight loss among the severely obese (NIH 1998). Behavioral and pharmacological treatments for obesity typically result in a 5 to 15 percent weight reduction when successful, though patients often have higher weight-loss goals (Foster et al. 1997). According to the National Heart, Lung, and Blood Institute, surgical intervention is an option when BMI > 40 or > 35 in the presence of comorbid conditions (e.g., hypertension, diabetes). Follow-up studies of weight-loss surgery patients demonstrate 49 percent maintenance of excess weight loss over a fourteen year period and resolution of many medical comorbidities (Pories 1995).
SEE ALSO Anthropology; Anthropology, Biological; Body Image; Body Mass Index; Disease; Obese Externality; Obesity; Overeating; Self-Esteem; Undereating
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weight / wāt/ • n. 1. a body's relative mass or the quantity of matter contained by it, giving rise to a downward force; the heaviness of a person or thing: he was at least 175 pounds in weight. ∎ Physics the force exerted on the mass of a body by a gravitational field. Compare with mass. ∎ the quality of being heavy: as he came upstairs the boards creaked under his weight. ∎ a unit or system of units used for expressing how much an object or quantity of matter weighs. ∎ a piece of metal known to weigh a definite amount and used on scales to determine how heavy an object or quantity of a substance is. ∎ the amount that a jockey is expected or required to weigh, or the amount that a horse can easily carry. ∎ any of several divisions based on relative lightness and heaviness into which boxers and wrestlers are classified for competition. ∎ the surface density of cloth, used as a measure of its quality. ∎ Printing the degree of blackness of a type font. 2. a heavy object, esp. one being lifted or carried. ∎ a heavy object used to give an impulse or act as a counterweight in a mechanism. ∎ a heavy object thrown by a shot-putter. ∎ (weights) blocks or discs of metal or other heavy material used in weightlifting or weight training. ∎ a burden or responsibility. 3. the ability of someone or something to influence decisions or actions: a recommendation by the committee will carry great weight. ∎ the importance attached to something: individuals differ in the weight they attach to various aspects of a job. ∎ Statistics a factor associated with one of a set of numerical quantities, used to represent its importance relative to the other members of the set. • v. [tr.] 1. hold (something) down by placing a heavy object on top of it: a mug half filled with coffee weighted down a stack of papers. ∎ make (something) heavier by attaching a heavy object to it, esp. so as to make it stay in place: the jugs were covered with muslin veils weighted with colored beads. 2. attach importance or value to: speaking, reading, and writing should be weighted equally in the assessment. ∎ (be weighted) be planned or arranged so as to put a specified person, group, or factor in a position of advantage or disadvantage: the balance of power is weighted in favor of the government. ∎ Statistics multiply the components of (an average) by factors to take account of their importance. 3. assign a handicap weight to (a horse). PHRASES: put on (or lose) weight become fatter (or thinner).throw one's weight around inf. be unpleasantly self-assertive.throw one's weight behind inf. use one's influence to help support.the weight of the world used in reference to a very heavy burden of worry or responsibility: he continues to carry the weight of the world on his shoulders.be a weight off one's mind come as a great relief after one has been worried.worth one's weight in gold (of a person) exceedingly useful or helpful.
weight, measure of the force of gravity on a body (see gravitation). Since the weights of different bodies at the same location are proportional to their masses, weight is often used as a measure of mass. However, the two are not the same; mass is a measure of the amount of matter present in a body and thus has the same value at different locations, and weight varies depending upon the location of the body in the earth's gravitational field (or the gravitational field of some other astronomical body). A given body will have the same mass on the earth and on the moon, but its weight on the moon will be only about 16% of the weight as measured on the earth. The distinction between weight and mass is further confused by the use of the same units to measure both—the pound, the gram, or the kilogram. One pound of weight, or force, is the force necessary at a given location to accelerate a one-pound mass at a rate equal to the acceleration of gravity at that location (about 32 ft per sec per sec). Similar relationships hold between the gram of force and the gram of mass and between the kilogram of force and the kilogram of mass.