|Activity, Energy Expenditure and Energy Requirements of Infants and Children (International Dietary Energy Consultative Group - IDECG, 1989, 412 pages)|
|The desirable upper limits of energy intake in childhood: Short- and long-term consequences|
The now standard response to any analysis of requirements is to specify the end points so that one can identify the objectives. This is the "requirements for what?" argument. If it is first accepted that one needs to begin by defining growth patterns we should then establish whether the growth rates are appropriate or not. Only then can we work back to the original question and ask how much food is required to achieve these defined optimal growth patterns.
The analyses of the effects of different energy intakes must be considered from both the short- and long-term standpoint. In the short term, it seems difficult to define an upper limit to growth rates beyond which the baby or child suffers. If there is a maximum growth rate then there should be an upper limit to energy needs; overfeeding beyond this point leads either to the energy being dissipated as heat or to the excess energy being deposited as tissue; the child is then likely to become obese.
On a short-term basis, theromogenesis is unlikely to lead to problems of overheating, even in hot climates, and modest states of obesity are unlikely to be harmful. Only when a gross excess of fat and weight has accumulated will physical problems develop, e.g., genu valgum, disfiguring striae or eventually the Pickwickian syndrome of respiratory decompensation. Such a development takes several years of excess energy accumulation; so it is difficult to consider this type of information when assessing the short-term impact of excess energy and how to use this in developing values for the energy requirements of infants.
The longer-term effects of more subtle changes in body composition, adiposity and metabolism are now receiving more attention (see below). The issue of modest childhood obesity remains important, however, because of the increasing evidence of a greater probability of adult obesity in those who were overweight in childhood. An analysis of the relationship between energy intake and childhood obesity is still therefore warranted.