Over the last decade physiological mechanisms have been revealed which have increased our understanding of the role of biology in controlling energy balance through processes of inhibition and termination of eating. However, in the majority of cases, these mechanisms do not constitute a biological imperative. The expression of appetite remains dependent upon an interaction between biology and the environment [4] and, at the present time, the environment contains extremely potent factors which for many people (adults and children) can readily overcome biological processes operating to maintain body weight.