R.G. Whitehead

High levels of energy expenditure in obese women

Total free living energy expenditure was compared in lean and obese women by the new doubly labelled water method and partitioned into basal metabolism and thermogenesis plus activity by whole body calorimetry. Average energy expenditure was significantly higher in the obese group (10.22 versus 7.99 MJ/day (2445 versus 1911 kcal/day); p less than 0.001) resulting from an increase in the energy cost of both basal metabolism and physical activity. Self recorded energy intakes were accurate in the lean subjects but underestimated expenditure by 3.5 MJ/day (837 kcal/day) in the obese group. Basal metabolic rate and energy expenditure on thermogenesis plus activity were identical in the two groups when corrected for differences in fat free mass and total body mass. In the obese women in this series there was no evidence that their obesity was caused by a metabolic or behavioural defect resulting in reduced energy expenditure.

Effects on birth weight and perinatal mortality of maternal dietary supplements in rural Gambia: 5 year randomised controlled trial .

Abstract Objective: To test the efficacy in terms of birth weight and infant survival of a diet supplement programme in pregnant African women through a primary healthcare system. Design: 5 year controlled trial of all pregnant women in 28 villages randomised to daily supplementation with high energy groundnut biscuits (4.3MJ/day) for about 20 weeks before delivery (intervention) or after delivery (control). Setting: Rural Gambia. Subjects: Chronically undernourished women (twin bearers excluded), yielding 2047 singleton live births and 35 stillbirths. Main outcome measures: Birth weight; prevalence of low birth weight (<2500 g); head circumference; birth length; gestational age; prevalence of stillbirths; neonatal and postneonatal mortality. Results: Supplementation increased weight gain in pregnancy and significantly increased birth weight, particularly during the nutritionally debilitating hungry season (June to October). Weight gain increased by 201 g (P<0.001) in the hungry season, by 94 g (P<0.01) in the harvest season (November to May), and by 136 g (P<0.001) over the whole year. The odds ratio for low birthweight babies in supplemented women was 0.61 (95% confidence interval 0.47 to 0.79, P<0.001). Head circumference was significantly increased (P<0.01), but by only 3.1 mm. Birth length and duration of gestation were not affected. Supplementation significantly reduced perinatal mortality: the odds ratio was 0.47 (0.23 to 0.99, P<0.05) for stillbirths and 0.54 (0.35 to 0.85, P<0.01) for all deaths in first week of life. Mortality after 7 days was unaffected. Conclusion: Prenatal dietary supplementation reduced retardation in intrauterine growth when effectively targeted at genuinely at-risk mothers. This was associated with a substantial reduction in the prevalence of stillbirths and in early neonatal mortality. The intervention can be successfully delivered through a primary healthcare system. Key messages In developing countries chronic maternal undernutrition is a prime contributor to the birth of over 25 million low birthweight babies annually and to high rates of neonatal mortality. An absence of well designed field trials has created uncertainty about the potential efficacy of maternal feeding programmes This large scale randomised controlled trial shows that dietary supplementation in pregnancy can be highly effective in reducing the proportion of low birthweight babies and perinatal mortality Incorporating supplementary feeding into a rural primary healthcare system is feasible Late pregnancy is the period most amenable to intervention

Season of birth predicts mortality in rural Gambia

We present evidence that events in early life strongly influence the adult survival prospects of rural Africans. Our analysis of births and deaths in three Gambian villages dating back to 1949 shows that people born during the annual ‘hungry season’ are up to 10 times more likely to die prematurely in young adulthood. A permanent effect of malnutrition on the development of the immune system during fetal growth seems a likely explanation.

Energy expenditure of Gambian women during peak agricultural activity measured by the doubly-labelled water method.

The doubly-labelled water (2H218O) method was used to measure total energy expenditure (TEE) in ten non-pregnant, non-lactating (NPNL), six pregnant (P) and fourteen lactating (L) women in a rural Gambian community. Measurements were made on free-living subjects at a period of peak energetic stress when high agricultural work loads coincided with a hungary season to induce moderately severe negative energy balance. TEE averaged 10.42 (SD 2.08) MJ/d, equivalent to 1.95 (SD 0.38) times resting metabolic rate (RMR). The energy cost of physical activity plus thermogenesis, derived as TEE-RMR, averaged 4.94 (SD 1.96) MJ/d. Expressed per kg body-weight (103 kJ/kg per d) this component of expenditure was 2.5 times greater than comparative values from inactive, affluent women studied previously (39 kJ/kg per d). Estimated energy intake (EI) in a subset of the women (n 13) was only 4.80 (SD 1.58) MJ/d, yielding an apparent deficit of 6.08 MJ/d between EI and TEE. Weight changes suggested that endogenous fat oxidation accounted for only about 0.85 MJ/d, leaving an unexplained difference of over 5 MJ/d. Critical analysis of possible errors suggests that the new doubly-labelled water method has provided the most reliable estimates and that the estimates of EI were substantially in error. This finding has important consequences for other food intake studies.

BACTERIAL CONTAMINATION IN TRADITIONAL GAMBIAN WEANING FOODS

Although emphasis on infant feeding is rightly being placed on breast-feeding, the need for safe weaning foods for the developing world must also receive its due attention. Traditional weaning foods used for young infants in a typical West African village can be as hazardous, bacteriologically, as commercial milk products, and providing a breast-fed child with supplements under the conditions which prevail in much of the developing world is potentially dangerous, whatever the source of the food.

UNEXPECTEDLY LOW LEVELS OF ENERGY EXPENDITURE IN HEALTHY WOMEN

A new method for measuring total energy expenditure (TEE) with stable isotopically labelled water (2H218O) was used to measure average daily energy expenditure over 14-21 day periods in 12 healthy women following their normal activity patterns. TEE expressed as a multiple of basal metabolic rate (TEE/BMR) averaged only 1 X 38 +/- 0 X 04. This result is at variance with the widely held assumption that minimum maintenance requirements are 1 X 5 times BMR.

PRENATAL DIETARY SUPPLEMENTATION OF AFRICAN WOMEN AND BIRTH-WEIGHT

Gambian women, who show marked seasonal fluctuations in energy balance, were offered a dietary supplement during pregnancy. This resulted in a net energy increment of 431 kcal/day. In the wet season, when the women were normally in marked negative energy balance due to food shortages and a high agricultural work load, the supplementation improved birth-weight by a mean of 224 g and reduced the incidence of low-birth-weight babies (less than 2.5 kg) from 28.2% to 4.7%. In the dry season, when the women were previously in positive energy balance despite an energy intake of only 60% of the recommended dietary allowance, the supplement had no beneficial effect on birth outcome. This threshold effect indicates the need to identify truly at-risk groups for prenatal supplementation programmes in developing countries.

INFLUENCE OF MATERNAL DIET ON PLASMA-PROLACTIN LEVELS DURING LACTATION

An improvement in maternal diet produced significant reductions in plasma-prolactin concentration at all stages of lactation. The prolonged high prolactin concentrations found in undernourished mothers may ensure milk synthesis when food intake is limited, by preferentially channelling nutrients towards the breast. The lower hormonal levels associated with improved maternal nutrition may shorten the period of post-partum infertility despite prolonged breast-feeding.

New method for measuring milk intakes in breast-fed babies.

A method for the measurement of milk intake in young breast-fed babies is described in which heavy water (2H2O) enrichment in saliva is measured on only two occasions after a single oral dose of 2H2O. Values obtained by this method are compared with those obtained by test-weighing. This new method is ideal for routine surveys since it does not interfere with feeding habits and maternal life style, and no technical expertise is required of the mother.

ARE CURRENT DIETARY GUIDELINES FOR YOUNG CHILDREN A PRESCRIPTION FOR OVERFEEDING

New estimates for the energy requirements of young children have been derived by combining the energy deposited during growth with measurements of total energy expenditure obtained by use of the new doubly-labelled water (2H2(18)O) method in 355 healthy infants aged 0-3 years. The resultant values of 110, 95, 85, 83, 83, 84, and 85 kcal/kg/day at 1, 3, 6, 9, 12, 24, and 36 months, respectively, are substantially lower than current Department of Health and Social Security and FAO/WHO/UNU recommended dietary allowances. Evidence from diet surveys suggests that changes in infant feeding practices are largely responsible for the apparent reduction in energy requirements. Dietary guidelines may need to be reappraised, to avoid overfeeding of infants.