4.1. Energy supply and physical growth of infants and children

1. Recent studies of energy intake in exclusively breast-fed children indicate that their energy requirements, as judged by growth, can be met by much lower intakes than those proposed in the 1985 report, which were based on the observed intakes of formula-fed infants.

2. Information about the BMR of infants and young children is consistent and satisfactory, but very little is known about their levels of physical activity. To fill this gap, more work is needed on instruments for investigating activity in young children. This subject is one of high priority.

3. A great deal remains to be learned about the relation between energy supply and amount and pattern of growth. Decreased growth in length compared with international references (stunting) is extremely common in developing countries. Factorial estimates of the nutrient requirements of children are all based on increments in weight. It is a tenable hypothesis, based on some supportive evidence, that growth in length is determined by the supply of protein or of factors associated with protein in foods, and that growth in weight is determined by growth in length, in order to maintain body composition.

4. Therefore, more studies are needed of the relationships between the intakes of energy and nutrients and the amount and pattern of growth. Such studies are particularly illuminating if they compare groups with different dietary patterns and are particularly important for children below three years. A number of valuable studies of this kind were done in the 1970s, but they seem to have fallen from favor. A major difficulty was that many children are still partially breast-fed at 2-3 years of age, so that accurate estimates of intakes were virtually impossible. This problem could now be overcome by using heavy water.