Indices of chronic energy deficiency in adults

There followed IDECG-sponsored meetings of the three of us in Rome and Lausanne which were wrongly seen by some of our amazed colleagues as gladiatorial battles. These began to draw crowds of onlookers intrigued to see our ideas range far and wide with a ferocity of debate which passes for tranquil, after-dinner musing in the colleges of English Oxbridge! We debated how to distinguish acute from chronic deficiency, energy depletion from other nutrient deficiencies, the storage state of the body from the capacity of organs to use energy, and the usefulness of tedious but accurate measurements conducted on individuals rather than the development of crude indices appropriate to populations. Without initially resolving these issues, we were soon in a debate about the validity of current data on energy requirements - which changed first when insufficient food was available? Did physical activity in behavioural, mechanical, physiological or biological efficiency terms alter fist, or did body weight start falling first only for these other changes to take over when body weight fell below critical thresholds? What now seems reasonably clear was at that stage very uncertain; confusion persisted as to whether the real need for a definition of CED was in the public health or economic development aspects of nutrition promotion programmes in the Third World.

John Waterlow produced our first draft which emphasized our agreement on the need to exclude states of progressive energy imbalance, which we termed acute energy deficiency. We surmised that in this state of changing energy stores we might have many more functional problems than that found when subjects had come once more into energy balance at a reduced rate of energy turnover. Waterlow drew on his experience of anthropometric data collected by John Durnin on British Army recruits, on Gopalan's and Shetty's data on Indian BMIs and on unpublished data by Pryer (1990) from the London School who had collected behavioural measures of illness in adult Bangladeshi men with different weights. There then followed the vexed question of whether adults of the same BMI had similar body composition in all parts of the world and how we could assess energy turnover in relation to the need for economically effective work, for desirable social activities or simply for a sense of wellbeing. This took us back to the debates in the 1981 Committee on Energy Requirements when Anna Ferro-Luzzi had set out these options. She then had to recalculate data from several previous surveys to find body compositional data and physical activity measurements appropriate to our use. By this stage the three of us were convinced that we needed to exclude remarkably thin but superbly fit athletes whom we guessed might abound in many developing countries where physical activity seemed an incessant part of daily life. We therefore chose BMI as the criteria and linked this with some measure of energy turnover which we instinctively saw as a PAL of 1.4 since this had featured in our FAO/WHO/UNU (1985) debate on energy requirements.

Further meetings by Anna Ferro-Luzzi and I then involved endless recalculations of data on men and women to see whether we were justified in having different thresholds for the two sexes. In the end, in the absence of sufficiently clear data, we plumped for the same cut-off points on the basis that biologically women were fatter than men at equivalent weights-for-height. We had already been responsible for proposing to FAD/WHO/UNU that in relation to energy requirements one could take standardizing figures for BMI of 18.7-23.8 for women and 20-25.0 for men, based on retrospective actuarial analyses of the post-war Metropolitan Life Insurance Tables. This difference had, however, been ignored by Garrow in simplifying the BMI classification for obesity by specifying a 20-25 range as normal for both women and men. We presumed that were we to adjust women's weights so that their body energy content was the same as men, then there might be serious physiological consequences and we surmised that the reproductive ability of women would certainly be impaired. Table 1 summarizes our initial proposals. At the time we were concerned about how best to link the BMI values with the measures of energy turnover. It seemed reasonable, however, to conform to the long-standing nutritional principles of having three grades of malnutrition, of increasing severity. This system was used by Gomez in his first assessment of childhood malnutrition (Gomez et al., 1956), and three grades were also proposed by Garrow (1981) for classifying obesity. It seemed reasonable to have a balance between a low BMI and a low energy turnover since we were unsure of their relative importance, so a BMI of 17-18.4 with a low energy intake might be as deleterious as a BMI of 17-17.9 but where energy was sufficient to provide more than the minimum of 1.4 times the basal metabolic rate (BMR).

Table 1. The original classification of chronic energy deficiency (CED) in adults

^aPAL (physical activity level) referred in the publication (James, Ferro-Luzzi & Waterlow, 1988) not only to the PAL expressed as a ratio of the basal metabolic rate but also as a general index of energy turnover. Thus it was envisaged (incorrectly - see text) that food intake could be used as an index of adequacy.