Notes on the new international estimates of energy requirements

Abstract

In the present paper I shall try to discuss the ideas and principles underlying the estimates of human energy requirements proposed by a consultative group set up by the Food and Agriculture Organization, World Health Organization and United Nations University, that met in Rome in October 1981 (FAO/WHO/UNU, 1985).I shall only consider adults, since Whitehead (1986) discusses the requirements of infants and young children. Intake v. expenditureIn the present report, estimated energy requirements are based more firmly than before on measurements of energy expenditure rather than of intake. An exception is in infants and children up to the age of 10 years, whose requirements are estimated from intakes because we do not know enough about their expenditure.The principle is not new, but it has been applied more rigorously than before. Of course, if people are in balance, maintaining constant body-weight, input and output will, over the long term, be equal, and it should not matter which is measured to give an estimate of energy requirement. Without embarking on the difficult question of whether energy balance is maintained through regulation of input or output or both, it seems to me common sense that because we have to expend energy, we need an intake, rather than the other way round. Thus expenditure is the primary factor.The word 'requirement', as generally used in relation to healthy people, refers to the habitual requirement over a period of time; a period that admittedly has not been specified. Requirement over I or 2 d makes no sense, except perhaps in people who are ill and whose state is rapidly changing. However, both intakes and outputs are usually measured over quite short periods of a few days on a finite number of subjects. The measurements, therefore, can only produce estimates of what is habitual and, because of the variation within and between individuals, they may be very much in error. Moreover, as is well known, even with the most careful technique, estimates of energy intake and output frequently do not agree (e.g. Norgan et al. 1974).There is in fact no reason to suppose that over the short term people do maintain an exact energy balance. Even if there are no changes in weight, alterations in body composition may occur that are too small to be detected by the methods currently available. For these reasons, in interpreting measurements of intake and output, it is important to have some idea of their variability.available at https://www.cambridge.org/core/terms. https://doi

Relationship between physical activity related energy expenditure and body composition: a gender difference

“…This resulted in an average %body fat of 30 (range 5±58) in the females and 21 (range 3±60) in the males. The average physical activity level values (PAL ADMR/ BMR) of 1.68 and 1.79 in the female and male groups, respectively, are close to the value for those engaged in moderate activity, and the range from 1.2±2.6 in both groups covers the minimum to maintain life up to the level for somebody engaged in heavy work 31,32 and represents the range for sustainable lifestyles. 10 Using age and physical activity as predictors for %body fat, we ®rst analyzed the relationship between age and %body fat.…”

Human eating behaviour in an evolutionary ecological context

“…Much of the literature on obesity and undernutrition among adults has focused on the maintenance of energy balance and the factors that lead to loss of balance, both short term and long term (Rothwell & Stock, 1982;Waterlow, 1986;Shetty, 1993;Ulijaszek, 1996;Ralph & James, 1999;Moore, 2000). Diet and physical activity are both strongly implicated in the regulation of body weight, with homeostatic physiological mechanisms defending the body against changes in energetics (Moore, 2000).…”

Human energetics methods in biological anthropology

“…At the level of the individual, measuring body composition and the partitioning of energy expenditure between bodily maintenance and activity allows possible adaptations to low (Shetty, 1990;Waterlow, 1990) and high (Norgan, 1990) energy availability to be examined. Specific adaptations that have been examined in this way include the level (Keys et al, 1950;Norgan, 1990) and efficiency of physical activity (Jones, 1989;Jones et al, 1987;Maloiy et al, 1986;Strickland and Ulijaszek, 1990) and down-regulation of basal metabolism (Ferro-Luzzi, 1990b;Shetty, 1984Shetty, , 1990Waterlow, 1986). In children, the partitioning of energy between growth and physical activity under conditions of low intake has yet to be researched, while adaptations to varying levels of energy intake have only recently been systematically investigated for pregnant (Durnin, 1988;Forsum et al, 1988) and lactating (van Raaij et al, 1990;Sadurskis et al, 1988;Schutz et al, 1980) women.…”

“…predicting the BMR from body weights for groups of ten normal, healthy European subjects using the Schofield (1985) equations are 5% and 6% for boys and girls under 3 years of age respectively, 2% for both males and females aged 3 to 10 years, 2% and 3% for males and females aged 10 to 18 years, respectively, 3% for both males and females aged 18 to 60 years, and 4% and 3% for males and females above the age of 60 years respectively (Schofield, 1985). It should be noted, however, that the Schofield equations overpredict the BMR of "abnormal" Europeans; reported values for BMRs of adult males after 24 weeks of semistarvation, and anorexic women between the ages of 17 and 32 years, showed values which were 68% and 59% respectively of those predicted (Waterlow, 1986;Casper et al, 1991). An investigator studying groups of Europeans that are in some way physiologically "abnormal," such as those grossly obese, starvedlsemistarved, or anorexic, should measure the BMRs and not rely on prediction equations.…”

“…Despite the inaccuracy of the assumption concerning variability of TEF (Horton, 1983), the TEE of an individual divided by hisher BMR is a better measure of daily physical activity level (PAL) in adults than most indices (James et al. 1988a) qince it is standardized for both body mass and biological variation in metabolic rate (Waterlow, 1986). In order to examine day-to-day variation in activity level, the use of activity diaries or heart rate monitoring in association with classical calorimetric techniques are appropriate for estimating TEE, since isotopic methods can only give values for TEE averaged across a number of days.…”