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close this bookActivity, Energy Expenditure and Energy Requirements of Infants and Children (International Dietary Energy Consultative Group - IDECG, 1989, 412 pages)
View the document(introductory text...)
View the documentIntroduction
Open this folder and view contentsEnergy requirements in normal infants and children
Open this folder and view contentsLow energy intakes and growth velocities of breast-fed infants: Are there functional consequences?
Open this folder and view contentsMethods to assess physical activity and the energy expended for it by infants and children
Open this folder and view contentsEstimation and validation of energy expenditure obtained by the minute-by-minute measurement of heart-rate
Open this folder and view contentsAssessment and significance of body composition in infants and children
Open this folder and view contentsTotal energy expenditure of free-living infants and children obtained by the doubly-labelled water method
Open this folder and view contentsReference data for total energy expenditure in early infancy
Open this folder and view contentsBasal metabolism of infants
Open this folder and view contentsEnergy cost of various physical activities in healthy children
Open this folder and view contentsThe energy requirements of growth and catch-up growth
Open this folder and view contentsEnergy cost of communicable diseases in infancy and childhood
Open this folder and view contentsEnergy-sparing mechanisms: reductions in body mass, BMR and activity: their relative importance and priority in undernourished infants and children
Open this folder and view contentsThe desirable upper limits of energy intake in childhood: Short- and long-term consequences
Open this folder and view contentsLong-term developmental implications of motor maturation and physical activity in infancy in a nutritionally at risk population
Open this folder and view contentsTemperament, activity and behavioral development of infants and children
Open this folder and view contentsThe cultural regulation of infant and child activities
Open this folder and view contentsShort- and long-term effects of low or restricted energy intakes on the activity of infants and children
Open this folder and view contentsThe relationship between undernutrition, activity levels and development in young children
View the documentIndicators for the extent to which energy requirements are being met in infants and children
View the documentImplications of new knowledge for recommendations of energy intakes
View the documentImplications of new knowledge for the prevention and treatment of PEM in infants and children
View the documentImplications of new knowledge for the prevention and treatment of obesity in infants and children
View the documentNeeds and priorities for research and action from the physiological point of view
View the documentNeeds and priorities for research and action from the behavioral point of view
View the documentNeeds and priorities for research and action from the point of view of policy
View the documentList of participants

Indicators for the extent to which energy requirements are being met in infants and children

(Discussion leader A.M. PRENTICE, rapporteur B. SCH√úRCH)

Indicators for the extent to which energy requirements are being met could, theoretically, include assessments of (1) energy intake, (2) growth, (3) physical activity, (4) morbidity, and (5) biochemical parameters (e.g., of protein turnover).

In the long term, people must be in energy balance, i.e., energy intakes must more or less equal energy expenditure. Recent estimates of total energy expenditure obtained with the doubly-labelled water method or based on multiples of measured BMR suggest that earlier measurements of apparently very low habitual intakes in certain population groups must be in error. Also, if we take measurements of energy intakes as an indicator, we have to decide what requirement is to be matched. There are many problems associated with this decision.

If we look at various components of growth, growth in length or height probably has to be excluded as an indicator of caloric adequacy because it is a very slow process that depends on many factors. It has been observed that stunted children have comparatively high intakes per kg body weight. Stunted Gambian children maintain the same fat mass as children of the same height in Cambridge. Changes in lean body mass might be worth exploring further. Thus, weight appears to be an appropriate but very gross indicator. It also may not be the first parameter to undergo changes when energy requirements are not being met.

A rough estimate of energy expended in physical activity can be obtained by measuring BMR and total energy expenditure, and by expressing the latter as a multiple of the former. On this basis and per kg body mass, stunted Gambian children do not differ in activity level from Cambridge children of normal height. The doubly-labelled water method does not seem to be sensitive enough to indicate the point at which energy intakes are so low that activity has to be reduced. Activity is also affected by other factors; e.g., by cultural constraint.

There is a relationship between undernutrition and morbidity, but it is difficult to isolate the role of energy deficiency in diets which most often are deficient in various nutrients as well.

Among biochemical parameters, urea kinetics might be worth further consideration.

Children often seem to be able to track along their centiles of growth curves despite their apparently insufficient diet. During infectious disease episodes their growth is interrupted, and the time afterwards, during which the child should be able to catch up, seems to be the critical period, when energy quality, energy density and micronutrient concentrations seem to be of importance. Under these circumstances, recovery often seems unduly delayed. This raises the question as to whether the diet during catch-up should be different from the normal diet and, if so, for how long during the recovery period children should be given such a special diet. It has also been observed that children do not particularly like foods with a high protein:energy ratio.

It is difficult to clearly define a disease episode. Seroconversion to hepatitis B. for instance, can take place without obvious symptoms, but this does not necessarily mean that this subclinical episode has no metabolic consequences. Scrimshaw's chapter refers to metabolic studies in which afebrile, asymptomatic infections with Q-fever or the 17-D strain of yellow fever used for immunizations resulted in significant catabolic losses.

It also still remains to be explained why healthy breast-fed babies grow more slowly than bottle-fed babies. Can a breast-fed baby with 20% fat mass possibly be energy deficient? The problem is that we know little about the bioavailability of these fat reserves, and other nutrients could be limiting growth. Metabolic changes can be observed in most energy-deficient children, but different children may have different capabilities of coping with energy deficiency.