Over the last decades, food has become more affordable
to larger numbers of people as the price of food has
decreased substantially relative to income and the concept
of 'food' has changed from a means of nourishment to a
marker of lifestyle and a source of pleasure. Clearly,
increases in physical activity are not likely to offset an
energy rich, poor nutritive diet. It takes between 1–2
hours of extremely vigorous activity to counteract a single
large-sized (i.e., >=785 kcal) children's meal at a fast food
restaurant. Frequent consumption of such a diet can
hardly be counteracted by the average child or adult [