Energy metabolism during the menstrual cycle, pregnancy and lactation in well nourished Indian women

The measured basal metabolic rates (BMR) of present day Indian women were found to be comparable to published BMRs, measured in Indian women over 50 years ago, but 7 percent lower than present European/American women. This can possibly be due to differences in body composition or climate. Schofield's equation, used to predict the BMR of women in the 18-30 age group from body weight, was found to over-estimate the BMR of young Indian women by approximately 9 percent. This commonly used equation also overestimates the BMR of young American women by almost 7 percent (Chapter 2). The BMR and the thermic effect of a meal (TEM) was measured in the pre- and post-ovulatory phases of a single menstrual cycle. BMR was not significantly different, however, the TEM was 18.5 percent higher (p&lt; 0.05) during the post-ovulatory phase, as compared to the pre-ovulatory phase of the same menstrual cycle. This increment in the TEM is small in absolute terms and is unlikely to affect the energy requirements of these individuals (Chapter 3). Both pregnancy and lactation are energetically expensive and would appear to require substantial increments in energy intake. However, the measured increment in energy intake rarely appears to be adequate to meet all the costs of pregnancy and lactation. Therefore, saving of energy by an enhancement of the efficiency of maternal energy metabolism was postulated as a possible mechanism by which the costs of pregnancy and lactation are met. Therefore, the BMR and TEM were measured at 12, 24, and 34 weeks of gestation (Chapter 4), as well as, 12 and 24 weeks of lactation (Chapter 5), in a group of well nourished Indian women and compared to a group of non-pregnant, non-lactating controls. No energy saving was associated with either the BMR or TEM during pregnancy or lactation. However, the dietary energy intake, estimated at the same time as the metabolic measurements, appeared to be substantially increased during the last two trimesters of pregnancy and during the initial 24 weeks of lactation; and was apparently adequate to meet the extra energy expenditure associated with pregnancy and lactation.</p

Consistency of metabolic responses and appetite sensations under postabsorptive and postprandial conditions

The present study aimed to investigate the reliability of metabolic and subjective appetite responses under fasted conditions and following consumption of a cereal-based breakfast. Twelve healthy, physically active males completed two postabsorption (PA) and two postprandial (PP) trials in a randomised order. In PP trials a cereal based breakfast providing 1859 kJ of energy was consumed. Expired gas samples were used to estimate energy expenditure and fat oxidation and 100 mm visual analogue scales were used to determine appetite sensations at baseline and every 30 min for 120 min. Reliability was assessed using limits of agreement, coefficient of variation (CV), intraclass coefficient of correlation and 95% confidence limits of typical error. The limits of agreement and typical error were 292.0 and 105.5 kJ for total energy expenditure, 9.3 and 3.4 g for total fat oxidation and 22.9 and 8.3 mm for time-averaged AUC for hunger sensations, respectively over the 120 min period in the PP trial. The reliability of energy expenditure and appetite in the 2 h response to a cereal-based breakfast would suggest that an intervention requires a 211 kJ and 16.6 mm difference in total postprandial energy expenditure and time-averaged hunger AUC to be meaningful, fat oxidation would require a 6.7 g difference which may not be sensitive to most meal manipulations

Increased bone mineral density in Aboriginal and Torres Strait Islander Australians: Impact of body composition differences

Bone mineral density (BMD) has been reported to be both higher and lower in Indigenous women from different populations. Body composition data have been reported for Indigenous Australians, but there are few published BMD data in this population. We assessed BMD in 161 Indigenous Australians, identified as Aboriginal (n = 70), Torres Strait Islander (n = 68) or both (n = 23). BMD measurements were made on Norland-XR46 (n = 107) and Hologic (n = 90) dual-energy X-ray absorptiometry (DXA) machines. Norland BMD and body composition measurements in these individuals, and also in 36 Caucasian Australians, were converted to equivalent Hologic BMD (BMDH) and body composition measurements for comparison