In many developed economies child obesity levels doubled between the 1960s and the 1980s, and have doubled again since then (Lobstein et al., 2004). By 2005, one third of all US children were affected by excess body weight, and children
in other developed economies have been following the US pattern. Even in emerging and less developed economies, child obesity prevalence levels are also rising (Wang and Lobstein, 2006), especially in urban areas where the need for physical activity is lower
and the opportunities for sedentary behaviour and access to energy‐dense foods and beverages far greater. As child obesity is strongly predictive of adult obesity and of chronic disease, the child obesity epidemic has been described as "a massive tsunami" (Ludwig,
2005), and "a health time‐bomb" (Chief Medical Officer, 2003).