Obesity
Introduction A critical turning point in the history of human food consumption has become evident. With famine and undernutrition the central food issues for much of human history, we now face the opposite: overnutrition and obesity. The number of individuals who are overnourished now equals or exceeds the number undernourished (WHO, 1998), and the prevalence of obesity is increasing in every corner of the world. The percentage of individuals in the USA who are either overweight or obese rose from 55.9% in 1994 to 65.7% in 2002 (Flegal et al., 2002; Hedley et al., 2004) leading the Centers for Disease Control and Prevention to apply the word ‘epidemic’ (CDC, 2004). The most widely used index of obesity is the body mass index (BMI), which is calculated as weight in kilograms divided by height in meters squared (i.e. kg/m2). The World Health Organization defined obesity as a BMI ≥ 30 kg/m2, given epidemiological data showing that mortality at this weight is increased by 30% (Manson et al., 1995). Premature deaths associated with obesity are primarily attributable to cardiovascular disease, Type II diabetes and several cancers (Pi-Sunyer, 1993) (see chapters on ‘Coronary heart disease’ and ‘Diabetes mellitus’). Obesity also carries many additional complications including hypertension, sleep apnoea, gall bladder disease and osteoarthritis (see ‘Hypertension’, ‘Sleep apnoea’ and ‘Osteoarthritis’). Some, but not all, data suggest that obesity is associated with increased risk for psychological distress, including binge eating and depression.
