Total energy expenditure (H218O), physical activity level and milk output of lactating rural Bangladeshi tea workers and nontea workers.

OBJECTIVE: To assess the total daily energy expenditure (TDEE), milk output and physical activity level (PAL) of chronically malnourished lactating women using the doubly labelled water method (DLW). DESIGN: Prospective, longitudinal study designed to assess the extent of malnutrition and energetics of lactating tea workers and nontea workers. SETTING: North-east Bangladesh on women working and living in the same tea estates. SUBJECTS: Of an original cohort of 150 lactating women, 30 were selected to participate in this study when they were at about 12 months postpartum. One mother subsequently dropped out. INTERVENTIONS: On day 1 each women provided a urine sample, was administered a dose of DLW and 6 h later provided another sample. Further urine samples were collected for 21 subsequent days. In addition, every 5 days the mother provided a milk sample and at the same time her baby provided a urine sample. RESULTS: Mean (s.d.) BMI was 17.4 (1.63). Mean TDEE and PAL were significantly higher in workers than nonworkers (8.42 (1.38) and 6.83 (2.09) MJ/day, P = 0.02 and 1.92 (0.34) and 1.59 (0.44), P = 0.03, respectively). Mean milk output was similar in the two groups (672 (180) ml and 749 (189) ml in workers and nonworkers, respectively). CONCLUSIONS: Based on international BMI cutoffs, 79% of mothers were suffering from some degree of chronic energy deficiency. A total of 35% of workers and 17% of nonworkers were engaged in strenuous physical activity. The mean milk output of both workers and nonworkers was not different and was high especially as most of the mothers were about 12 months postpartum. No relationship was found between menses return and any of the variables studied. SPONSORSHIP: World Health Organization, Nestle Foundation, UNICEF.

Increasing starch intake in the human diet increases fecal bulking.

Fecal bulking occurs through water holding by dietary residue as well as by enhanced bacterial mass as a result of bacterial utilization of dietary fiber. In this study, increasing the energy intake of human subjects by supplementing the carbohydrate content of the diet with corn starch increased fecal weights and fecal nitrogen content. This indicates that the carbohydrate content, more specifically the starch content, of the diet influences fecal bulking by possibly increasing available substrates for colonic bacterial proliferation which are dependent largely on undigested fiber in the colon. This may explain why high fecal weights occur in the tropics on comparable intakes of dietary fiber but on high starch intakes.

The influence of different methods on basal metabolic rate measurements in human subjects.

While collating basal metabolic rate (BMR) measurements made worldwide it becomes important to know how different instruments compare with each other and whether errors in methodology could account for the differences in BMRs measured. BMRs of 34 healthy individuals were measured by using five different instruments in various combinations. Results show that energy outputs were comparable between the oxylog. Hartmann and Braun Metabolator, ventilated tent and hood, and whole-body indirect calorimeter: small differences, if any, were not statistically significant. However, significant interactions existed between subjects with the ventilated tent and hood and calorimeter when measurements were taken in subjects who were unaccustomed to the apparatus. When converting O2-consumption measurements to energy output, some instruments make assumptions that introduce a variable error in the final result, which may lead to systematic errors during the compilation of large databases of human BMRs.

Alterations in fuel selection and voluntary food intake in response to isoenergetic manipulation of glycogen stores in humans.

This study investigated the relative importance of alterations in carbohydrate intake or oxidation as mechanisms for rectifying extreme perturbations of glycogen stores. Six lean men were studied on three occasions in which a stabilization period (days 1 and 2) was immediately followed by whole-body indirect calorimetry (days 3-5). Glycogen stores were manipulated on days 3 and 4 by using isoenergetic diets providing carbohydrate at 79% (HC), 48% (MC), or 9% (LC) of energy. Free access to MC meals and snacks was allowed on days 5 and 6 outside the calorimeter. The manipulations caused large alterations in glycogen stores (HC, +206 g; MC, +132 g; LC, -121 g; HC vs LC, 327 g), but subsequent voluntary food intake was very similar across treatments (HC, 18.2 MJ/36 h; MC, 17.7 MJ/36 h; LC, 18.1 MJ/36 h, NS). Over days 3-5 the average difference in carbohydrate intake (HC vs LC) was 16.1 MJ (1010 g), but balances differed by only 1.7 MJ (110 g) because of autoregulatory changes in carbohydrate oxidation. These were the only significant mechanisms for reestablishing carbohydrate balance.

Changes in energy expenditure, anthropometry, and energy intake during the course of pregnancy and lactation in well-nourished Indian women.

Basal metabolic rate (BMR), thermic effect of a meal (TEM), anthropometry, and dietary intakes were measured in 18 control subjects; 18 pregnant women at 12, 24, and 34 wk gestation; and in 17 of these women at 12 and 24 wk postpartum, to uncover any metabolic economy associated with either pregnancy or lactation. Results indicated that the BMR and TEM were not associated with any energy saving either during pregnancy or lactation. Mean weight gain from 12 wk gestation to term was 11.4 +/- 3.7 kg; mean birth weight of the infants was 3.06 +/- 0.41 kg. Estimated gain in adipose tissue and fat mass were 3.1 +/- 3.6 and 2.5 +/- 2.9 kg, respectively. Energy cost of pregnancy was estimated to be 303 +/- 171 MJ. The cumulative increase in energy intake over the last two trimesters of pregnancy was 290 +/- 280 MJ, meeting a large part of the total estimated cost of pregnancy. Weight gained by infants who were exclusively breast-fed from birth to 12 wk of age was used as a proxy indicator of adequate lactational performance. The extra energy required during lactation appeared to have been met largely by increases in energy intake, rather than by any metabolic economy or increase in fat mobilization.

PIP: Researchers compared data on 18 nonpregnant, nonlactating staff and students (controls) with data on 18 pregnant women at 12, 24, and 34 weeks gestation and on 17 of these women at 12 and 24 weeks postpartum to determine any changes in maternal energy metabolism during pregnancy and lactation. All controls and cases were healthy and recruited at St. John's Medical College and Hospital in Bangalore, India. They had unlimited access to food. Mean birth weight stood at 3.06 kg. Pregnant women gained, on average, 11.4 kg between 12 weeks gestation and term. They also gained 3.1 kg of adipose tissue and 2.5 kg in fat mass during the same period. The total energy cost of pregnancy was 303 MJ. Pregnant women experienced a cumulative increase in energy intake over the last trimesters of pregnancy of 290 MJ, satisfying a considerable part of the total estimated cost of pregnancy. Neither the basal metabolic rate nor the thermic effect of a meal were related to any energy saving during pregnancy or lactation. Energy intake was significantly higher than that of controls at 24 and 34 weeks gestation (9.01 and 9.33 vs 7.58 MJ/d) and at 12 and 24 weeks postpartum (9.6 and 9.09 vs. 7.58 MJ/d) (p 0.05). The proxy indicator of adequate lactational performance was weight gain of infant between birth and 12 weeks. At 12 weeks, the body weights were similar to the 50th percentile of the NCHS weight-for-age. These findings suggest that increases in energy intake met the need for extra energy needed during lactation and that metabolic economy and increase in fat mobilization did not occur.

Resting metabolic rate and thermic effect of a meal in the follicular and luteal phases of the menstrual cycle in well-nourished Indian women.

The resting metabolic rate (RMR) and thermic effect of a standard test meal (TEM) were measured twice each during the follicular and luteal phases (confirmed by plasma concentrations of progesterone and estradiol) of a single menstrual cycle, and once during the follicular phase of the following menstrual cycle, by using indirect calorimetry, in 13 well-nourished Indian women. There was a significant increase in the TEM (P < 0.05) (6.72 +/- 1.57% vs 7.96 +/- 1.48% of the energy content of the test meal for follicular and luteal phases, respectively) of 18.5% during the luteal phase of the menstrual cycle but no significant difference in the RMR or postmeal total energy output (PMTEO). Dietary energy and macronutrient intakes in all subjects in both phases of the menstrual cycle were also similar. The RMR and the PMTEO were also similar when measured in the follicular phase of consecutive menstrual cycles.

Reduced postexercise recovery oxygen consumptions: an adaptive response in chronic energy deficiency?

Maximal aerobic capacity (VO2max) and oxygen consumption during recovery were measured in well-nourished control subjects (C) and compared with results from chronically energy-deficient (CED) subjects in the same age range. The absolute VO2max was lower in undernourished subjects (2.5 +/- 0.1 L/min [C] v 1.8 +/- 0.1 L/min [CED]; mean +/- SEM, P < .001); however, when expressed per kilogram fat-free mass (FFM), the values were comparable. The total O2 debt was higher in the well-nourished group even when corrected for FFM differences (249.1 +/- 17.1 v 147.3 +/- 9.2 mL/kg FFM; P < .001). O2 consumption in the recovery period returned to baseline values rapidly and in a single phase in undernourished subjects. In contrast, a slow biphasic decline was observed in well-nourished control subjects. The postexercise recovery phase may be an important period during which energy-saving may occur in chronically undernourished human subjects.

Repeated infusions of identical doses of norepinephrine show potentiation of metabolic responses in human subjects.

Thermogenic responses to similar doses of norepinephrine appear to be different when repeatedly administered. This hypothesis was tested by three consecutive 30-minute infusions of a fixed dose of norepinephrine separated by a rest period of one hour between infusions. There was a significant increase or potentiation of the metabolic response as measured by oxygen consumption to the third dose of norepinephrine, while the cardiovascular responses showed no change. It is therefore important to make allowances for this phenomenon when assessing intergroup differences in regulatory thermogenesis using dose-response protocols for norepinephrine administration.

Prediction of steady-state oxygen consumption during norepinephrine infusions in humans.

A method for predicting maximal oxygen consumption during norepinephrine infusion is described. Using the initial response and enzyme kinetics, predicted values of maximal oxygen consumption were compared with observed values and a coefficient of variation of 1.4% was obtained. This method is of use in situations where it may not be possible to achieve steady-state conditions, especially with high doses of norepinephrine, and it permits comparison of maximal oxygen consumption between groups.

Malnutrition and the immune response. 1. Malnutrition in the community: recent concepts.

Anthropometric indicators have long been used to define the nutritional status of children although anthropometric studies of adult nutritional status have been accorded low priority. As a result, the nutritional status of a community is largely based on estimates of childhood undernutrition alone. The prevalence of adult undernutrition is also variably estimated since objective measures of adult undernutrition are not applied. Body mass index may provide an ideal method for filling this gap since this simple anthropometric index well reflects the physiological, social and economic consequences of adult undernutrition in a community. It also enables assessment of the impact of intervention strategies aimed at developmental or public health outcomes in population groups world-wide.

Adaptation to low energy intakes: the responses and limits to low intakes in infants, children and adults.

Reduction in energy intake below the acceptable level of requirement for an individual results in a series of physiological and behavioural responses, which are considered as an adaptation to the low energy intake. This ability of the human body to adapt to a lowering of the energy intake is without doubt beneficial to the survival of the individual. However, what is more controversial is the view held by some that the body can metabolically adapt in a beneficial manner to a lowered intake and consequently that the requirements for energy are variable given the same body size and composition and physical activity levels. Much of this confusion is the result of considerable evidence from studies conducted in well-nourished adults who, for experimental or other reasons, have lowered their intakes and consequently demonstrated an apparently enhanced metabolic efficiency resulting from changes in metabolic rates which are disproportionate to the changes in body weight. Similar increases in metabolic efficiency are not readily seen in individuals who on long-term marginal intakes, probably from childhood, have developed into short-statured, low-body-weight adults with a different body composition. It would thus appear that the generally used indicator of metabolic efficiency in humans, that is a reduced oxygen consumption per unit fat free mass, is fraught with problems since it does not account for variations in contributions from sub-compartments of the fat free mass which include those with high metabolism at rest such as brain and viscera and those with low metabolism at rest such as muscle mass. Metabolic rate per unit fat free mass thus, does not reflect true variations in metabolic efficiency and is due largely to variations in body composition. This finding combined with the evidence that behavioural adaptation in habitual physical activity patterns which occurs on energy restriction is not necessarily beneficial to the individual raises doubts about the role of adaptation to low intakes in determining one's requirement for energy. The evidence is overwhelming that both in children and adults, changes in body size and composition as well as in levels of habitual physical activity may be the most important consequences of a lowered energy intake and cannot be assumed to be a part of a beneficial adaptation that influences energy requirements.

Role of the sympathetic nervous system in adaptation to seasonal energy deficiency.

The sympatho-adrenal system is involved in the regulation of energy metabolism and responds to changes in energy intake. Energy restriction diminishes the sympathetic drive while overfeeding increases it. Chronically energy deficient subjects show an enhanced alpha and beta receptor responsiveness, which may be of a denervation type, associated with the reduced sympathetic activity that results from the decrease in dietary energy intake. The reduced basal metabolism of energy restricted subjects is partly attributable to the decrease in sympathetic activity. Chronically energy deficient individuals also show a suppressed thermogenic response to infusions of adrenergic agonists such as noradrenaline. Although sympathetic activity plays a modulating role in the energy homeostasis of the chronically energy deficient, it is not possible to explain seasonal fluctuations in energy balance.

Basal metabolic rates of Indian women.

Basal metabolic rates (BMRs) in 60 Indian women resident in Bangalore and aged 18-30 years were measured during the mid-follicular phase of the menstrual cycle. The data were used to obtain a predictive equation for BMR from body weight. The BMR measurements were comparable to BMRs of 52 Indian women reported more than 50 years ago, while they were 9.2% lower than Schofield's equation and 4.2% lower than that predicted by the equation of C.K.J. Henry & D.G. Rees (1991) Eur. J. Clin. Nutr. 45, 177-185. The equation obtained in this study predicts closely the BMRs of American women but underestimates BMRs of European women compared with figures recently reported in the literature.

Basal metabolic rates and metabolic economy in chronic undernutrition.

Basal metabolic rates (BMR) and body composition were measured in 130 adult Indian males, selected from three socio-economic groups. Results show a significantly lower BMR in the chronically undernourished, with a greater dependence on carbohydrate as fuel in the fasted state. When expressed as per kg body weight or kg fat-free mass (FFM), the BMRs are significantly higher in these individuals. The latter observations suggest variations in the contribution of viscera and skeletal muscle to the FFM, with a relatively greater visceral to muscle mass ratio. However, on adjustment for differences in weight and FFM by means of an analysis of covariance, the chronically undernourished (both urban and rural) have significantly lower BMRs. This indicates a 'metabolic economy' in these individuals, which could be attributable in part to their significantly lower serum T3 levels. When the subjects are classified on the basis of grades of chronic energy deficiency (CED), individuals with low body mass index (BMI) (less than 17 and below) are not similar in their basal metabolism. Those individuals from good socio-economic backgrounds with access to ad libitum energy and protein intake but with low BMI have comparable BMRs to the well nourished. It may therefore be unwise to classify all individuals with low BMI 'across the board' as suffering from CED. Socio-economic scaling may be a useful addition to the present classification of CED.

Plasma norepinephrine kinetics are unaltered in chronically undernourished adult subjects.

Twelve healthy adults divided into a well-nourished (WN; n = 6) and a chronically energy deficient (CED; n = 6) groups underwent a single 30 min infusion of norepinephrine (NE) administered at the rate of 0.15 micrograms/kg fat-free mass/min. Measured parameters in the basal state and during the infusion included heart rate (by electrocardiograph), stroke volume, cardiac output and other cardiac indices (by impedance cardiography) and blood pressure recordings. The data are suggestive of fairly similar cardiovascular responses in the CED and WN subjects, with the exception of cardiac inotropy (i.e. strength of cardiac muscle contractility) and changes in total peripheral resistance, both of which were enhanced in the CED. Peak NE levels of both groups during the infusion were similar and so was the clearance rate for NE corrected for fat-free mass differences. Although plasma half-life of NE tended to be higher in the CED group, plasma appearance rates of NE were comparable between the groups, suggesting that plasma NE kinetics were not altered in CED adults.

Reduced thermoregulatory thermogenesis in undernutrition.

Adaptive responses to chronic energy deficiency could occur in one of the important components of energy expenditure ie, regulatory thermogenesis. We assessed the thermogenic responses to standardized noradrenaline (NA) infusions in undernourished labourers, as well as in normally nourished control subjects. There was a significant suppression (greater than 60 per cent) of NA-stimulated oxygen consumption in the undernourished, which remained statistically significant even when the responses were corrected for fat-free mass differences. This first report of a suppression in regulatory thermogenesis indicates its important role in the adaptive response to lower than required energy intakes in human subjects.

Predictive equations for basal metabolic rates of Indian males.

The article deals with the generation of a prediction equation for basal metabolic rate (BMR) of well-nourished Indian males, from prospective measurements on 121 males, using a single validated technique. The equation related BMR to simple measures such as weight (WT) and age, and was given by: BMR (kJ/d) = 48.7 * WT-14.1 * AGE + 3599. The equation was internally as well as externally validated against other Indian databases and the net differences of < 2% (100 kJ/d), were non-significant. Interestingly, American BMRs were predicted to within 0.5% (28 kJ/d) by this equation, while European BMRs were significantly higher than predicted by 6.3% (433 kJ/d). Similar results were obtained on validating the American and European data against the equations of C. K. J. Henry & D. G. Rees (1991) Eur J. Clin. Nutr. 45, 177-185. Such results suggest that there are no differences in the BMR of age- and weight-matched Asian Indian males, other tropical populations and Americans. This has implications in the estimation of energy expenditure and hence energy requirements for these populations.

Day-to-day variations in basal metabolic rates and energy intakes of human subjects.

Variations in BMR, body weight and energy intake were measured for 14 consecutive days in 6 young adults on ad libitum energy intakes, whose physical activity was uncontrolled. Energy intakes showed significant differences between days (P less than 0.025, CV = 6.7 per cent), between weeks (P less than 0.005, CV = 8.9 per cent) and between subjects (P less than 0.005, CV = 7.9 per cent). Energy intakes were 14 per cent higher (P less than 0.01) at weekends. Intra-individual variance contributed up to 86 per cent of the total variance in the energy intake. Replicate BMR measurements showed non-significant differences from day to day (CV less than 1.5 per cent), a training effect from week to week (P less than 0.05, CV = 1.5 per cent), and significant differences between subjects (P less than 0.001, CV = 12.4 per cent). Intra-individual variance contributed only 14 per cent to the total variance in BMR. There were no significant changes in body weight (CV = 0.7 per cent) or fat-free mass during the study. Auto-correlations of BMR, body weight and energy intake were non-significant at the different lag times studied. Cross-correlations between the above parameters were also non-significant for each subject. It is concluded that despite wide fluctuations in energy intake from day to day within an individual, the variations in BMR are small with a true CV of less than 1.5 per cent. Hence these variations are unlikely to be important while assessing energy requirements on the basis of the FAO/WHO/UNU (1985) BMR factorial method.

The value of arm circumference measurements in assessing chronic energy deficiency in Third World adults.

OBJECTIVE: To assess the usefulness of mid-upper arm circumference (MUAC) as a substitute for body mass index (BMI: kg/m2) or an additional measure of adult nutritional state. DESIGN: Variously sampled adults aged 18-60 years from selected regions of five African countries, India, China and Papua New Guinea were measured. SUBJECTS: 2421 men and 3248 women were measured for their heights, weights and MUAC. Of these, 1569 men and 1905 women also had their triceps skinfold thickness measured, thus allowing additional estimates of muscle area circumferences and fat areas in the arm. RESULTS: MUAC and BMI were highly correlated in each national group; each group's MUAC differed from the overall mean MUAC at any BMI value by < 10%. Women's MUACs were smaller than men's at equivalent BMIs. Increases in MUAC with age were statistically significant but trivial. Muscle and fat measurements showed similar increases with BMI; a larger muscle mass in men explained their greater MUACs but muscle differences alone did not explain national variations in MUAC. The -1 SD MUAC value, taken as an independent measure of peripheral tissue wasting, readily distinguished those with a BMI < 16.0 from those with a BMI > 18.5; intermediate grades of BMI were poorly specified by MUAC values. CONCLUSION: MUAC values of 23.0 cm in men and 22.0 cm in women are useful cut-off points for simple screening of nutritional state. In combination with BMI it may provide a more refined classification of CED. This new combined classification scheme may be a better means of discriminating the at-risk underweight adults from those who are thin but not at risk.

Metabolic responses to episodes of partial dietary restriction in undernourished Wistar rats.

Wistar rat pups raised in large litters (LL) and small litters (SL) prior to weaning had access to ad libitum dietary intakes up to the age of 90 days. At 90 and again at 180 days they were partially diet restricted for a period of 15 days. Body weights, resting metabolic rates (RMR) and capacity for nonshivering thermogenesis (NST) was evaluated prior to, during and after the period of energy restriction. Responses were compared with 180 day rats from both groups who had been diet restricted for the first time at 180 days. Body weight losses were greater in the latter group. Groups of rats exposed to dietary restriction once, had higher body weights than rats of identical ages who had not been restricted. RMR decreased in all groups during restriction. However, reductions in NST were seen only in nutritionally deprived animals and in well-nourished controls who were partially restricted once. Changes in NST contribute to metabolic efficiency seen during episodic dietary restriction.