The Nestlé Lecture. Chronic undernutrition and metabolic adaptation

Influence of nutritional status on basal metabolic rates among rural agriculturalists of Ngilo-Ilo, East Java

OBJECTIVES

Previous research has shown that tropical island populations have reduced basal metabolic rates (BMR) associated with the joint influences of heat stress and undernutrition. This study examines variation in BMR among an indigenous population of Indonesia, and compares these data with those collected from earlier studies in Indonesia.

METHODS

Anthropometric dimensions and BMR were measured on a sample of 35 Indonesian adults (28 men, 7 women) from the rural village of Ngilo-Ilo, East Java.

RESULTS

Mean measured BMRs (±SD) were 1433 ± 344 kcal/d in men and 1256 ±257 kcal/d in women, and were not significantly different from estimates using the FAO/WHO/UNU predictive questions. Underweight individuals (BMIs <18.5 kg/m² ) had BMRs that were 7.6% below predicted levels, while those with BMIs ≥18.5 kg/m² had BMRs that were 8.0% above predicted levels (P < .01). Underweight individuals also had significantly higher respiratory quotients (RQ = .94 vs. .89; P < .05), suggesting lower levels of fat oxidation. Compared to data from previous studies (1929-1979), men of the Ngilo-Ilo sample had similar BMIs (19.8 vs. 19.2 kg/m² ), but higher BMRs, after adjusting for age and body weight (+2.1% vs. -5.6%; P < .05).

CONCLUSIONS

Among the agriculturalists of Ngilo-Ilo, measured BMRs were low, but not significantly different from those predicted by the FAO/WHO/UNU equations. Among subjects of this sample and from earlier studies, poorer physical nutritional status was associated with reduced BMRs. These results suggest that chronic energy stress has consistently shaped metabolic function among Indonesian rural populations.

Metabolic vs. hedonic obesity: a conceptual distinction and its clinical implications

Body weight is determined via both metabolic and hedonic mechanisms. Metabolic regulation of body weight centres around the 'body weight set point', which is programmed by energy balance circuitry in the hypothalamus and other specific brain regions. The metabolic body weight set point has a genetic basis, but exposure to an obesogenic environment may elicit allostatic responses and upward drift of the set point, leading to a higher maintained body weight. However, an elevated steady-state body weight may also be achieved without an alteration of the metabolic set point, via sustained hedonic over-eating, which is governed by the reward system of the brain and can override homeostatic metabolic signals. While hedonic signals are potent influences in determining food intake, metabolic regulation involves the active control of both food intake and energy expenditure. When overweight is due to elevation of the metabolic set point ('metabolic obesity'), energy expenditure theoretically falls onto the standard energy-mass regression line. In contrast, when a steady-state weight is above the metabolic set point due to hedonic over-eating ('hedonic obesity'), a persistent compensatory increase in energy expenditure per unit metabolic mass may be demonstrable. Recognition of the two types of obesity may lead to more effective treatment and prevention of obesity.

Energy requirements of adults

Objectives

To describe issues related to energy requirements of free living adults and discuss the importance of basal metabolic rate (BMR) and their relationships to total energy expenditure (TEE ) and physical activity level (PAL, derived as TEE/BMR) and to determine the influence of body weight, height, age and sex.

Design

Based on a review of the literature, this paper examines the variability in BMR due to methodology, ethnicity, migration and adaptation (both metabolic and behavioural) due to changes in nutritional status. Collates and compiles data on measurements of TEE in free living healthy adults, to arrive at limits and to compare TEE of populations with different life-styles.

Results and Conclusions

The constancy of BMR and its validity as a reliable predictor of TEE in adults as well as the validity of PAL as an index of TEE adjusted for BMR and thus its use to categorise the physical activity pattern and lifestyle of an individual was confirmed. The limits of human daily energy expenditure at around 1.2×BMR and 4.5×BMR based on measurements made in free living adults have been reported in the literature. A large and robust database now exists of energy expenditure measurements obtained by the doubly labelled water method in the scientific literature and the data shows that, in general, levels of energy expenditure are similar to the recommendations for energy requirements adopted by FAO/WHO/UNU (1985). The review also confirms that metabolic adaptation to energy restriction is not an important factor that needs to be considered when recommending energy requirements for adults in developing countries.

The conceptual framework for estimating food energy requirement

Objective

In anticipation of the revision of the 1985 Food and Agricultural Organization/World Health Organization/United Nations University (FAO/ WHO/UNU) Expert Consultation Report on ‘Energy and Protein Requirements’, recent scientific knowledge on the principles underlying the estimation of energy requirement is reviewed.

Design

This paper carries out a historical review of the scientific rationale adopted by previous FAO/WHO technical reports on energy requirement, discusses the concepts used in assessing basal metabolic rate (BMR), energy expenditure, physical activity level (PAL), and examines current controversial areas. Recommendations and areas of future research are presented.

Conclusions

The database of the BMR predictive equations developed by the 1985 FAO/WHO/UNU Expert Consultation Report on Energy and Protein Requirements needs updating and expansion, applying strict and transparent selection criteria. The existence of an ethnic/tropical factor capable of affecting BMR is not supported by the available evidence. The factorial approach for the calculation of energy requirement, as set out in the 1985 report, should be retained. The estimate should have a normative rather than a prescriptive nature, except for the allowance provided for extra physical activity for sedentary populations, and for the prevention of non-communicable chronic diseases. The estimate of energy requirement of children below the age of 10 years should be made on the basis of energy expenditure rather than energy intake. The evidence of the existence of an ethnic/tropical factor is conflicting and no plausible mechanism has as yet been put forward.

The effect of long term combined yoga practice on the basal metabolic rate of healthy adults

Background

Different procedures practiced in yoga have stimulatory or inhibitory effects on the basal metabolic rate when studied acutely. In daily life however, these procedures are usually practiced in combination. The purpose of the present study was to investigate the net change in the basal metabolic rate (BMR) of individuals actively engaging in a combination of yoga practices (asana or yogic postures, meditation and pranayama or breathing exercises) for a minimum period of six months, at a residential yoga education and research center at Bangalore.

Methods

The measured BMR of individuals practicing yoga through a combination of practices was compared with that of control subjects who did not practice yoga but led similar lifestyles.

Results

The BMR of the yoga practitioners was significantly lower than that of the non-yoga group, and was lower by about 13 % when adjusted for body weight (P < 0.001). This difference persisted when the groups were stratified by gender; however, the difference in BMR adjusted for body weight was greater in women than men (about 8 and 18% respectively). In addition, the mean BMR of the yoga group was significantly lower than their predicted values, while the mean BMR of non-yoga group was comparable with their predicted values derived from 1985 WHO/FAO/UNU predictive equations.

Conclusion

This study shows that there is a significantly reduced BMR, probably linked to reduced arousal, with the long term practice of yoga using a combination of stimulatory and inhibitory yogic practices.

Factors influencing variation in basal metabolic rate include fat-free mass, fat mass, age, and circulating thyroxine but not sex, circulating leptin, or triiodothyronine

BACKGROUND

Basal metabolic rate (BMR) is the largest component of daily energy demand in Western societies. Previous studies indicated that BMR is highly variable, but the cause of this variation is disputed. All studies agree that variation in fat-free mass (FFM) plays a major role, but effects of fat mass (FM), age, sex, and the hormones leptin, triiodothyrionine (T3), and thyroxine (T4) remain uncertain.

OBJECTIVE

We partitioned the variance in BMR into within- and between-subject effects and explored the roles of FFM, FM, bone mineral content, sex, age, and circulating concentrations of plasma leptin, T3, and T4.

DESIGN

This was a cross-sectional study of 150 white adults from northeast Scotland, United Kingdom.

RESULTS

Only 2% of the observed variability in BMR was attributable to within-subject effects, of which 0.5% was analytic error. Of the remaining variance, which reflected between-subject effects, 63% was explained by FFM, 6% by FM, and 2% by age. The effects of sex and bone mineral content were not significant (P > 0.05). Twenty-six percent of the variance remained unexplained. This variation was not associated with concentrations of circulating leptin or T3. T4 was not significant in women but explained 25% of the residual variance in men.

CONCLUSIONS

Our data confirm that both FFM and FM are significant contributors to BMR. When the effect of FM on BMR is removed, any association with leptin concentrations disappears, which suggests that previous links between circulating leptin concentrations and BMR occurred only because of inadequate control for the effects of FM.

Effect of feeding malnourished patients for 1 mo on mitochondrial complex I activity and nutritional assessment measurements

BACKGROUND

We showed previously that the activity of complex I (the first enzyme of the electron transport chain) in peripheral blood mononuclear cells decreases with malnutrition and increases to a subnormal value after 1 wk of refeeding, but the traditional markers of nutritional status do not do so.

OBJECTIVE

The aim of this study was to ascertain whether a period of nutritional intervention longer than 1 wk would normalize complex I activity and traditional markers of nutritional status.

DESIGN

Fifteen malnourished patients (7 women and 8 men) with > or =10% body weight loss over the previous 6 mo were studied on the day of their admission to hospital and 7, 14 and 30 d after the beginning of nutritional support. Complex I activity in peripheral blood mononuclear cells, weight, height, body composition, body water compartments, dietary intake, and serum albumin concentrations were measured on each occasion. The results before and during nutritional intervention were compared with values obtained in 30 healthy volunteers (17 women and 13 men).

RESULTS

Complex I activity increased significantly after the first week of refeeding (P < 0.001) and reached a normal value after 1 mo of nutritional supplementation. Among the classic markers of nutritional status, only the ratio of extracellular water to intracellular water tended to decrease over the refeeding period.

CONCLUSION

Complex I activity increases rapidly and is normalized by refeeding at a time when other markers of nutritional status do not change significantly.

Dietary, evolutionary, and modernizing influences on the prevalence of type 2 diabetes

An evolutionary perspective is used to elucidate the etiology of the current epidemic of type 2 diabetes estimated at 151 million people. Our primate legacy, fossil hominid, and hunting-gathering lifestyles selected for adaptive metabolically thrifty genotypes and phenotypes are rendered deleterious through modern lifestyles that increase energy input and reduce output. The processes of modernization or globalization include the availability and abundance of calorically dense/low-fiber/high-glycemic foods and the adoption of sedentary Western lifestyles, leading to obesity among both children and adults in developed and developing countries. These trends are projected to continue for a number of decades.

Human eating behaviour in an evolutionary ecological context

Present-day human eating behaviour in industrialised society is characterised by the consumption of high-energy-density diets and often unstructured feeding patterns, largely uncoupled from seasonal cycles of food availability. Broadly similar patterns of feeding are found among advantaged groups in economically-emerging and developing nations. Such patterns of feeding are consistent with the evolutionary ecological understanding of feeding behaviour of hominids ancestral to humans, in that human feeding adaptations are likely to have arisen in the context of resource seasonality in which diet choice for energy-dense and palatable foods would have been selected by way of foraging strategies for the maximisation of energy intake. One hallmark trait of human feeding behaviour, complex control of food availability, emerged with Homo erectus (1.9 x 10(6)-200000 years ago), who carried out this process by either increased meat eating or by cooking, or both. Another key trait of human eating behaviour is the symbolic use of food, which emerged with modern Homo sapiens (100000 years ago to the present) between 25000 and 12000 years ago. From this and subsequent social and economic transformations, including the origins of agriculture, humans have come to use food in increasingly elaborate symbolic ways, such that human eating has become increasingly structured socially and culturally in many different ways.

Obesity and its potential mechanistic basis

Obesity plays a central role in the development of the thrifty phenotype. The metabolic disturbances of the cardiovascular metabolic syndrome, frequently ascribed to the thrifty phenotype, are rare in the absence of obesity and their expression is generally proportional to the size of the excess fat mass. Thus obesity interacts with early-life programming in the establishment of disease. Surprisingly, the evidence that fetal or infant diet leads to programming of obesity itself is rather weak, though this may be explained by the fact that life-style influences obscure the linkage between metabolic predisposition and maturity-onset obesity. This paper summarises the possible metabolic basis of obesity with special reference to those processes for which there are plausible mechanisms by which long-term programming may operate. It is concluded that the newly-emerging molecular discoveries in body weight regulatory systems point to the need for detailed studies of gene-environment interactions and life-course influences before we will fully understand the aetiology of complex phenotypes such as the metabolic syndrome.

Body composition in children with celiac disease and the effects of a gluten-free diet: a prospective case-control study

BACKGROUND

Celiac disease is the most common cause of malnutrition in children of Western countries.

OBJECTIVE

The objective was to measure body composition in children at the time celiac disease was diagnosed and after consumption of a gluten-free diet (GFD).

DESIGN

We assessed body composition by dual-energy X-ray absorptiometry in 29 children and adolescents with a mean (+/-SD) age of 9.5 +/- 3.4 y at the time celiac disease was diagnosed and in a subset of 20 patients after 1.2 +/- 0.2 y of a GFD. We also studied 23 patients aged 21.2 +/- 4.6 y who consumed a GFD for 10.6 +/- 4.5 y. Each patient was matched with a healthy control subject of the same age and sex.

RESULTS

Untreated patients weighed less than control subjects (P = 0.04). Fat mass and bone mineral content were lower in the patients than in the control subjects (P < 0.01), as was lean mass of the limbs (P = 0.0013). After approximately 1 y of the GFD, there were no significant differences in body-composition values between patients and control subjects. Similarly, body-composition values of celiac disease patients who consumed the GFD long term were comparable with those of healthy subjects.

CONCLUSIONS

Remarkable abnormalities in body composition were found in children at the time of diagnosis of celiac disease. Appropriate dietary treatment reverses body-composition abnormalities quickly and the beneficial effects of gluten withdrawal are persistent. Because these results are harder to achieve if celiac disease is first diagnosed in adulthood, efforts to encourage early diagnosis of celiac disease should be made.

Long-term physiological and economic consequences of growth retardation in children and adolescents

The application of a lifespan perspective in human biology in recent years has shown that a number of early environmental factors influencing human growth and development have long-term biological or psycho-social consequences. Human growth is characterized by prolonged infancy, an extended childhood phase and high rates of growth during the adolescent growth spurt. It is unlikely that these characteristics would have evolved without having advantages, and curtailments have the potential for disadvantage. The present paper examines the evidence for long-term physiological and economic consequences of growth retardation in children and adolescents. The emphasis is the biological and economic imperatives of survival, subsistence, reproduction and production rather than aspects of metabolic competence. Many of the consequences of growth retardation are determined by the direct effect on body size, but many other consequences arise from the conditions that cause the growth retardation. Catch up of retarded growth can occur, but does not usually do so because of the continued presence of the retarding agents. Basal metabolism and physical work capacity are usually commensurate with the size of the individual; mechanical efficiency of physical work is unchanged, but falls in activity levels may occur along with a reduction in the pace of activity. Growth retardation in childhood is associated with a higher disease and mortality risk in adulthood, with decreased productivity and employment and promotion prospects. Studies are showing that relative deprivation and the accumulation of socially patterned exposures are important in some societies. Height and growth retardation have proved invaluable in reflecting these factors, but the next generation of studies may require more discriminating indices.

No evidence for an ethnic influence on basal metabolism: an examination of data from India and Australia

A lower BMR of Indians, when compared with Westerners matched for age, sex and either surface area or body weight, has often been reported in the literature and has been interpreted to reflect an ethnic influence on BMR. To determine the contribution of body composition to these observed differences in BMR, we analysed the data on ninety-six Indians and eighty-one Caucasian Australians of both sexes, aged 18-30 years, studied in Bangalore, India and Melbourne, Australia. Absolute BMR and BMR adjusted for body weight were significantly lower in Indians when compared with Australians of the corresponding sex. However, BMR adjusted for fat-free mass (FFM) in men, and BMR adjusted for FFM and fat mass (FM) in women, were not significantly different between the two groups. Stepwise regression of FFM, FM, sex (0 = women; 1 = men) and ethnicity (0 = Indian; 1 = Australian) on BMR, resulted in the following relationship for the combined data on all subjects: BMR = 88.7 x FFM (kg) + 1713 (n 177; r 0.92; r2 0.85; SEE 425 kJ). The Indian equations of Hayter & Henry (1994), based on body weight, resulted in a significant bias (measured-predicted BMR) of 318 (SE 54) kJ/d in Indian men and -409 (SE 70) kJ/d in Indian women. The equation of Cunningham (1991), based on FFM, accurately predicted the BMR of Indian men, Indian women and Australian men. The small but significant bias of 185 (SE 61) kJ/d in Australian women, may be explained by the significant contribution of FM to BMR in this group. The present study does not provide any evidence for an ethnic influence on basal metabolism. The results strongly support the use of FFM, rather than body weight, for the prediction of BMR in population groups of varying body size and composition. This would allow an accurate estimation of BMR and hence energy requirements in population groups worldwide.

Differences in metabolic variables between adult coeliac patients at diagnosis and patients on a gluten-free diet

BACKGROUND

Coeliac patients often have nutrient malabsorption with nutritional status impairment, but no report on their energy requirements is available. In this study body composition, dietary habits, basal energy expenditure, and substrate oxidation were investigated in patients with the classic form of coeliac disease.

METHODS

Sixteen untreated and 18 adult coeliac patients on a gluten-free diet participated in the study. Body composition was assessed by anthropometry and bioimpedance. Energy expenditure was measured by indirect calorimetry. A food diary over 7 days was collected.

RESULTS

Coeliac patients showed reduced body weight components but not a different fat-free mass percentage compared with age- and sex-matched healthy volunteers. Basal metabolic rate normalized by fat-free mass (BMR/FFM) was higher in coeliac patients than in controls. Untreated patients showed a significantly higher non-protein respiratory quotient with regard to both treated patients (P < 0.01) and controls (P < 0.05), an increased percentage of carbohydrate intake, and a good correlation between lipid faecal loss and carbohydrate oxidation (Spearman R = 0.74; P < 0.01).

CONCLUSIONS

Both groups of patients had lower fat mass and FFM content than controls. The preferential carbohydrate oxidation in untreated patients might be a result of both lipid malabsorption and high carbohydrate intake.

Adult malnutrition: simple assessment techniques for use in emergencies

The recent recognition of the problem of adult malnutrition requires methods for specifying the severity of undernutrition. The measurement of mid upper arm circumference (MUAC) can now be used as a screening method for underweight (normally assessed from the BMI) or as an additional criterion with the BMI to identify the preferential loss of peripheral tissue stores of fat and protein. By analysing and extrapolating anthropometric data from nine detailed adult surveys from Asia, Africa and the Pacific a series of MUAC cut-off points have now been identified to allow the screening of individual adults under extreme conditions, e.g. during famine. Grade 4 malnutrition is now specified for those with a MUAC < 200 mm for men and < 190 mm for women since these MUAC values correspond to the loss of fat stores at BMI of < 13. Food supplementation is clearly needed in these individuals. Extreme wasting (grade 5 malnutrition) corresponds to MUAC values of < 170 and < 160 mm for men and women respectively. These adults have extremely low BMI, i.e. about 10, have lost most, if not all, of their protein stores and are at a high risk of imminent death. These individuals will need immediate special feeding regimens to ensure their survival. The sex-specific MUAC values corresponding to BMI of 16, 13 and 10 can now therefore be used for rapid screening and the choice of remedial action.

Relation of fetal growth to adult muscle mass and glucose tolerance

Recent studies show reduced fetal growth is associated with insulin resistance and a raised prevalence of glucose intolerance in adult life. Because early growth retardation in animal models leads to permanent changes in body composition and a reduction in the mass of muscle, a major insulin sensitive tissue, reduced adult muscle mass could explain the link between impaired fetal growth and glucose intolerance. To investigate this hypothesis, muscle mass has been determined in a group of men and women aged around 50 who were born in Preston, Lancashire and compared with their birthweight or body size at birth and their current insulin resistance and glucose tolerance. Subjects who had lower birthweights were shorter and lighter but their weight adjusted for height (BMI) was similar to that of other subjects. Much of the difference in weight was accounted for by a reduction in muscle mass. Muscle mass as estimated by the urinary creatinine excretion rose from 18.8% of body weight in women who had birthweights of 2.5 kg or less to 24.7% of bodyweight in those with birthweights of 3.4 kg or more. Trends in men were similar. Regression analysis showed that adult muscle mass was predicted by low birthweight (p = 0.004), low placental weight (p = 0.02), and small head circumference (p = 0.02) but not, however, by thinness at birth, the birth measurement most predictive of insulin resistance. In addition there were no significant relationships between muscle mass and insulin resistance or glucose tolerance in either men or women.(ABSTRACT TRUNCATED AT 250 WORDS)

The role of energy expenditure in energy regulation: findings from a decade of research

The role of energy expenditure in energy regulation remains a subject of continuing controversy. New data have emerged from studies conducted over the last decade demonstrating that energy expenditure is a critical factor contributing to successful energy regulation in normal individuals, as well as to the disregulation of energy balance that characterizes obesity. Reduced energy expenditure appears to facilitate weight gain in individuals susceptible to obesity and also appears to reduce the extent of body energy loss during undereating in both lean and obese individuals. The magnitude of the reduction in energy expenditure during, and perhaps after, weight loss is greater than expected on the basis of the reduction in body weight and appears to occur in response to undefined underlying determinants of energy regulation. In addition, exercise intervention studies and cross-sectional investigations of the relationship between energy expenditure for physical activity and body composition demonstrate an apparent equilibration between physical activity and body fat content. This equilibration is suggestive of a direct influence of physical activity on the underlying metabolic determinants of energy balance.