Year-round high physical activity levels in agropastoralists of Bolivian Andes: results from repeated measurements of DLW method in peak and slack seasons of agricultural activities.

By the repeated use of the doubly labeled water method (DLW), this study aimed to investigate (1) the extent of changes in energy expenditure and physical activity level (PAL) in response to increased agricultural work demands, and (2) whether the seasonal work demands induce the changes in the fairly equitable division of work and similarity of energy needs between men and women observed in our previous study (Phase 1 study; Kashiwazaki et al., 1995: Am J Clin Nutr 62: 901-910). In a rural small agropastoral community of the Bolivian Andes, we made the follow-up study (Phase 2, 14 adults; a time of high agricultural activity) of the Phase 1 study (12 adults; a time of low agricultural activity). In the Phase 2 study, both men and women showed very high PAL (mean+/-SD), but there was no significant difference by sex (men; 2.18 +/- 0.23 (age; 64 +/- 11 years, n = 7), women; 2.26 +/- 0.25 (63 +/- 10 years, n = 7)). The increase of PAL by 11% (P = 0.023) in the Phase 2 was equally occurred in both men and women. The factorial approach underestimated PAL significantly by approximately 15% (P < 0.05). High PAL throughout the year ranging on average 2.0 and 2.2 was attributable to everyday tasks for subsistence and domestic works undertaking over 9-11 h (men spent 2.7 h on agricultural work and 4.7 h on animal herding, whereas women spent 7.3 h almost exclusively on animal herding). The seasonal increase in PAL was statistically significant, but it was smaller than those anticipated from published reports. A flexible division of labor played an important role in the equitable energetic increase in both men and women.

Complementary feeding with cow's milk alters sleeping metabolic rate in breast-fed infants.

Although it is widely accepted that energy expenditure in infants is a function of feeding pattern, the mechanism behind this is not well understood. The objectives of this observational study were as follows: 1) to compare minimal observable energy expenditure (MOEE) between 2 subgroups of breast-fed infants, a BM group in which breast milk was the only source of milk and a BCM group given cow's milk in addition to breast milk; and 2) to identify potential mediators of a feeding pattern effect. For this purpose, infants were classified by feeding group on the basis of a mother's recall. Respiration calorimetry was used to measure MOEE in 62 infants (n = 35 BM, n = 27 BCM) aged 8.7 mo in Pelotas, southern Brazil. Breast-milk intake was measured using deuterium oxide, complementary food intake by 1-d food weighing, total energy expenditure and total body water using doubly labeled water; anthropometric indices were calculated. MOEE was 1672 +/- 175 kJ/d in BM compared with 1858 +/- 210 kJ/d in BCM infants (P < 0.001). Mass-specific MOEE was 201 +/- 24.6 and 216 +/- 31.9 kJ/(kg . d) in BM and BCM infants, respectively (P = 0.041). MOEE (kJ/d) was mediated by protein intake and fat-free mass (R(2) = 41.4%). We conclude that complementary feeding with cow's milk alters the sleeping metabolic rate in breast-fed infants. These findings deserve attention in relation to "metabolic programming" and the development of obesity later in life.

Lactation counseling increases breast-feeding duration but not breast milk intake as measured by isotopic methods.

The importance of exclusive breast-feeding in the first 6 mo of life is widely recognized, but most mothers still do not reach this goal. Several studies have shown that face-to-face lactation counseling is effective in increasing not only exclusive breast-feeding rates but also the total duration of breast-feeding. However, it is unclear whether counseling could increase breast milk intake. The purpose of this study was to evaluate the effect of lactation counseling on breast milk intake, assessed through the deuterium dilution method. This was a blind, randomized intervention trial of lactation counseling in a sample of 188 babies born in Pelotas, selected with the same criteria used for the WHO Multicentre Growth Reference Study (MGRS). The main outcomes were breast-feeding pattern and duration for all infants as well as breast milk intake for a subsample of 68 infants at the age of 4 mo. Mothers in the control group were almost twice as likely to stop breast-feeding by 4 mo as those in the intervention group (prevalence ratio 1.85; P = 0.04). Cox regression confirmed that the velocity of weaning was twice as high in the control group. Breast milk and total water intakes did not differ between the groups. The deuterium dilution technique proved to be a practical means of assessing breast milk intake. Lactation counseling reduced early weaning, but breast milk intake at 4 mo was not affected.