Relationship between anthropometric indices of body fat distribution and basal energy metabolism in healthy Maltese women.

A sample taken from a population (Maltese) with a high incidence of the metabolic complications of central obesity was studied to determine: (1) whether the standard Schofield equations adequately predict the basal metabolic rate (BMR) in this population; (2) whether the Maltese have a greater tendency for central obesity compared with other populations; (3) whether the distribution of body fat influences energy expenditure and fuel selection. Healthy women responding to a public advertisement were sampled randomly from the Maltese population. Correlation analysis and analysis of variance were used to study relationships between BMR and body composition. Anthropometric parameters (including body fat distribution indices, bioimpedance) and BMR were measured after an overnight fast. Six percent of the respondent were excluded because of recent illness, instability of diet or of body weight. Fifty subjects attended a clinic at the Medical School. The distribution of excess fat between central and peripheral areas in the Maltese population was similar to that reported for the British population. The Waist-hip ratio (WHR) reflected neither basal heat production (BMR) nor the contribution of fat oxidation to BMR. The Schofield equations systematically underestimated BMR by 5.4% +/- 0.86% (P < 0.05). The study suggests a limitation in using the Schofield equations for predicting BMR in the female Maltese population studied. It also suggests that the fat distribution between central and peripheral areas in this population has no effect on BMR.

Total energy expenditure in intravenously fed patients measured by the doubly labeled water technique.

The potential clinical use of the doubly labeled water (DLW) technique to measure total energy expenditure (TEE) in intravenously fed patients was assessed by applying the technique to 13 stable patients receiving total parenteral nutrition (TPN). TEE was compared with resting energy expenditure (REE), which was measured using a ventilated hood (n = 13), and with 24-hour energy expenditure (24h EE) measured in a whole-body calorimeter (n = 6). Daily measurements of urinary enrichment in 2H and 18O showed predominantly small and covariant fluctuations in elimination rates of these two tracers. The standard error of the estimate (SEFCO2) for the CO2 production rate (FCO2), which includes additional errors due to variability in isotopic fractionation, was calculated to be 2.65% +/- 0.70% of FCO2. TPN-related changes in background isotopic enrichment in subjects who were not dosed with isotope virtually ceased 10 days after starting intravenous feeding. TEE (4.99 +/- 1.10 kJ/min), TEE/REE (1.21 +/- 0.16 kJ/min), TEE/basal metabolic rate (]BMR] 1.31 +/- 0.16 kJ/min), and TEE (isotopic)/24h EE (calorimetric; 1.07 +/- 0.18 kJ/min) showed wide variability. This study provides some evidence for the validity of the DLW method in selected patients receiving TPN, since significant deviations from the assumptions of the method were not found in the subjects studied. The error associated with 2H sequestration during fatty acid synthesis is likely to be small, but could not be accurately measured. The contributions of activity and thermogenesis to TEE varied greatly, but overlapped with those reported in normal subjects.

The potential use of dual frequency bioimpedance in predicting the distribution of total body water in health and disease.

The distribution of water between extracellular fluid (ECF; measured by the inulin dilution technique) and intracellular fluid (ICF; calculated as the difference between total body water, which was measured by the deuterium dilution technique, and ECF) was measured in 12 healthy subjects. The results were compared with predictions made by anthropometry and whole body impedance obtained at 1kHz (Z(1)) and 50 kHz (Z(50)). Z(1) and Z(50) were also measured in 82 health subjects and 27 patients without clinically detectable oedema, and in 10 patients with oedema. Anthropometry and height(2)/Z(1) showed similar correlations with inulin space (r = 0.64, SEE = 1.74 L and r = 0.65, SEE = 1.75 L respectively). The ratios of Z (1)Z (50) in oedematous patients (1.03 +/- 0.02), which were universally lower than those obtained in normal subjects (1.18 +/- 0.04), overlapped with those obtained in patients without oedema (1.11 +/- 0.05). The study suggests that in this group of normal subjects low frequency bioimpedance measurements are not superior to anthropometric estimates of ECF. They also suggest a limitation in the use of the dual frequency bioimpedance meter to distiguish between patients with and without oedema.

Intravenous carbohydrate over-feeding: a method for rapid nutritional repletion.

Forty-four measurements of resting energy expenditure (REE) and respiratory quotient (RQ), and sequential measurements of body composition and nitrogen excretion were made in a cachectic male patient with inactive Crohn's disease, who was repleted with intravenous nutrition alone, over a period of 62 days. The initial energy intake (EI) of 10 MJ/day was increased to 21 MJ/day by three stepwise increments ( approximately 4MJ) in the glucose content of the feed. REE increased from 4.2 to 6.8 kJ/min, and body weight from 53 to 76kg. REE rose by a progressively greater amount with each increment in energy intake (DeltaREE DeltaEl = 0.12 to 0.26 ). The RQ increased progressively to a value up to 1.19 and persisted above 1.0 even 9h after the feed was stopped. The results suggest that the increase in REE a) was due to a combination of increasing lean body mass and increasing diet-induced thermogenesis, b) dissipated only a small proportion of the total energy infused, and c) was associated with net lipid synthesis from carbohydrate whilst on and off the feed. The results are discussed in relation to the energy equivalent of ATP and the circulating concentrations of insulin and the flux of substrates across forearm tissue.

Energy expenditure and substrate metabolism measured by 24 h whole-body calorimetry in patients receiving cyclic and continuous total parenteral nutrition.

1. Twenty-four hour energy expenditure and its components, i.e. 'basal metabolic rate', activity energy expenditure and diet-induced thermogenesis were measured, using continuous whole-body indirect calorimetry, in patients receiving total parenteral nutrition while in remission from Crohn's disease (weight 51.9 +/- 9.9 kg, body mass index 19.2 +/- 2.0 kg/m2). 2. Total parenteral nutrition was infused continuously over 24 h in four subjects and cyclically, between 22.00 and 10.00 hours, in eight subjects. Twenty-four hour energy expenditure (6.83 +/- 1.10 MJ/24 h) was lower than total energy intake (10.09 +/- 1.63 MJ/24 h), resulting in a positive energy balance (3.26 +/- 1.42 MJ) in all subjects. Repeated measurements of resting energy expenditure in the continuously fed subjects (5.82 +/- 1.11 MJ/24 h) did not change significantly at different times of day (coefficient of variation 2.2-6.6%). In contrast, in cyclically fed subjects, resting energy expenditure was 24.2 +/- 9.0% higher towards the end of the 12 h feeding period than the 'basal metabolic rate', which was measured just before the start of the feeding period. 3. Diet-induced thermogenesis, calculated as the increment in resting energy expenditure above 'basal metabolic rate' over the 24 h period (adjusted for the reduction in energy expenditure during sleep), was found to be 0.60 +/- 0.29 MJ or 6.1 +/- 3.1% of the energy intake. 4. The energy cost of activity (activity energy expenditure) in the continuously fed patients, calculated as the difference between 24 h energy expenditure and the integrated 24 h measurements of resting energy expenditure, was 0.88 +/- 0.53 MJ, i.e. 12.9 +/- 5.9% of the 24 h energy expenditure. 5. The non-protein non-glycerol respiratory quotient exceeded 1.0 for varying periods of time (0.5-17 h) in 11 subjects, indicating net lipogenesis from carbohydrate. 6. The results demonstrate favourable rates of deposition, during intravenous feeding, of both energy and nitrogen over a 24 h period in patients recovering from an episode of Crohn's disease. The efficacy of these commonly used total parenteral nutrition regimens in these patients is related to three features that are absent in normal healthy individuals, namely a low basal metabolic rate, a low activity-related energy expenditure and prolonged periods of lipogenesis from carbohydrate.

Inter-observer variability in the measurement of body composition.

The inter-observer variation in simple bedside assessments of body composition has been evaluated in 12 healthy adult subjects (6 male and 6 female) by 6 observers. Systematic bias between observers was found to be evident in each of the basic measurements (except height) and in each of the estimates of body composition (except those derived from weight and height alone). The largest residual coefficients of variation (rCV) for the basic measurements were found for skinfold thickness (11-18 per cent for individual skinfold thicknesses, and 9 per cent for the sum of four skinfold thicknesses), and the lowest for weight (0.01 per cent for digital scales, and 0.05 per cent for beam balance) and height (0.4 per cent). The rCV for whole-body resistance (1.2 per cent), forearm resistance (5.4 per cent) and near infra-red interactance (optical density 1: 5.6 per cent and optical density 2: 6.2 per cent) measurements were found to have intermediate values. The variability in the estimate of body fat obtained by skinfold thickness (rCV = 4.6 per cent) and near infra-red interactance methods (rCV = 4.2 per cent) was found to be greater than that from the resistance method (rCV = 2.6 per cent) and by methods based on weight and height alone (rCV = 1.1 per cent). The variability in the estimate of fat-free mass showed the same trend as that for body fat, but the rCVs were less due to the greater mass of the fat-free body compared to body fat.(ABSTRACT TRUNCATED AT 250 WORDS)

Bedside and field methods for assessing body composition: comparison with the deuterium dilution technique.

Estimates of body composition by the deuterium dilution technique were made in 55 healthy subjects (38 men and 17 women) with a mean age of 28.4 years, weight 65.5 kg and height 173.7 cm (body mass index 16.9-29.4 kg/m2). The results were compared with estimates obtained in the same subjects by 5 bedside techniques (skinfold thickness, impedance, resistance and 2 equations predicting body composition from weight and height). The results of all the bedside predictive methods were found to differ significantly from those of the deuterium dilution method (P less than 0.001). The Holtain impedance method underestimated the fat-free mass (FFM) obtained by deuterium dilution (50.8 +/- 7.9 kg) by a mean difference (mean bias) of 4.1 kg while the other methods overestimated FFM (mean bias or mean difference of -1.3 to -2.4 kg). The resistance (Valhalla equations) and skinfold methods showed the narrowest 95 per cent limits of agreement, when compared with the deuterium dilution technique, while the weight and height equations showed the widest limits of agreement. It is concluded that in this population, the resistance (Valhalla equations) and the skinfold thickness methods were the best predictors of body composition as measured by deuterium dilution. Discrepancies between the bedside methods and deuterium dilution method may be due to (a) methodological or biological differences between the test population used in this study and the original population used to validate the method, (b) differences in the structure of the equations used to interpret the measured biological variables, such as impedance and resistance, and (c) the use of predictive equations that are based on different 'reference' methods, such as deuterium dilution or densitometry, and on different assumptions. Predictive equations based on a combination of these reference methods are preferable to those based on single methods.

Ketone body metabolism in lean male adults during short-term starvation, with particular reference to forearm muscle metabolism.

1. Thirty-three arteriovenous forearm catheterization studies were carried out in 19 lean subjects starving for 12-14 h (n = 13), 30-36 h (n = 7) and 60-66 h (n = 13). Forearm blood flow was measured in order to calculate the flux of various substrates. At the same time, whole-body oxidation of fat, carbohydrate and protein was calculated using indirect calorimetry and urinary nitrogen excretion. 2. After an overnight fast (12-14 h), whole-body resting energy expenditure was accounted for by the oxidation of protein (15%), carbohydrate (17%) and fat (68%). At 30-36 h and 60-66 h of starvation, essentially all the non-protein energy was derived from the oxidation of fat (directly plus indirectly via ketone bodies). 3. After an overnight fast, acetoacetate and 3-hydroxybutyrate were taken up by forearm muscle at a rate which could account for 5% of the resting O2 consumption of this tissue. As starvation progressed, forearm muscle took up more acetoacetate and released 3-hydroxybutyrate so that the net uptake of ketone bodies was sufficient to account for about 10% of the resting O2 consumption at 30-36 h of starvation and about 20% at 60-66 h of starvation.(ABSTRACT TRUNCATED AT 250 WORDS)

The relationship between the circulating concentrations of interleukin 6 (IL-6), tumor necrosis factor (TNF) and the acute phase response to elective surgery and accidental injury.

The possible role of Interleukin 6 (IL-6) and tumour necrosis factor (TNF) in the regulation of the acute phase response to injury was studied in thirteen subjects undergoing elective surgery or suffering from multiple accidental injuries. The temporal changes in the circulating concentrations of these cytokines were related to the circulating acute phase protein concentrations (C-reactive protein and alpha 1 antichymotrypsin), white cell count, blood loss and duration of surgery. Circulating acute phase protein concentrations rose in all subjects during a thirty hour period following injury but none of the subjects showed a detectable rise in circulating concentrations of TNF. Peak circulating concentrations of IL-6 were detected between 4-6 hours after surgery/trauma but these showed a poor correlation with blood loss, fever, white cell count or duration of surgery. The peak concentrations of IL-6 typically occurred before the rise in circulating acute phase protein concentration. The data do not suggest a role for circulating TNF in the regulation of the acute phase response to injury. In contrast, IL-6 appears to be variably involved in the acute phase response but its precise role in mediating fever, leucocytosis and synthesis of acute phase proteins is as yet uncertain.