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Energy expenditure

20. Dietary energy intake and energy expenditure of women in rural Guatemala
21. Energy expenditure, dietary intake, and patterns of daily activity among various occupation groups in the Philippines
22. The energy expenditure of three categories of labourers in Southern China

20. Dietary energy intake and energy expenditure of women in rural Guatemala

Judith Snavely McGuire

Institute of Nutrition of Central America and Panama, Guatemala City, Guatemala, and Massachusetts Institute of Technology. Cambridge, Massachusetts, United States of America

Benjamín Torún

Institute of Nutrition of Central America and Panama. Guatemala City, Guatemala

Objectives

1. To determine the energy costs of the household and agricultural activities most frequently performed by adult women in a rural region of Guatemala.

2. To assess longitudinally the energy intake and total energy expenditure of such women throughout the agricultural cycle in that region.

Experimental Details

Subjects for Objective 1

Fifty-eight women, 16 to 49 years old (mean SD: 27 ± 6). of mixed Mayan and Caucasian descent (Lading). Weight. 49.1 ± 80 kg (range: 36.2-75.6). Height. 150 ± 6 cm (range: 144-163). Physiologic state. 12 in second or third trimester of pregnancy; 30 lactating; 16 neither pregnant nor lactating (NPNL).

Usual occupations: Mainly rural household-related activities, child-care and minor agricultural tasks, such as gleaning, winnowing, picking fruits, and tending domestic animals. Participated with other family members in picking cofee during the harvest season.

Subjects for Objective 2

Eighteen women selected from the preceding group, 18 to 31 years old 126 ± 3), who lived with a spouse, had at least one pre-school-age child, and who did not share household duties with another woman or an older child. Weight: 47.8 ± 4.7 kg. Height: 152 ± 6 cm. Physiologic state: Throughout the longitudinal 18month study, eight became pregnant, delivered an infant, and breast-fed it.

Study Environment

The study took place in Cacahuito, a small village of 1,043 inhabitants, located 1 13 km south-east of Guatemala City. It is at an altitude of 616 m above sea-level. The mean temperature during the day ranged from 21 to 33° C at various times of the year. The study lasted 18 months and included both the rainy (March-September) and dry seasons.

Diets

The women ate the foods traditional in the rural areas of Guatemala. They followed their customary meal pattern and no food supplements were provided. The staples were black beans (Phaseolus vulgaris) and corn, which provided about 65 per cent of the dietary protein. Animal foods provided about 15 per cent of the protein. The diets had a low energy density, mainly because of their low fat content (usually about 15 per cent, including inherent "invisible fat"). Nutrient intakes were calculated from 24-hour dietary recall surveys and Central American food composition tables.

Physical Activity

The women lived in their home environment and engaged in their normal day-to-day activities. They were asked to repeat or perform some of those activites for 10 to 15 minutes in order to measure the energy cost of the work. The time-motion observations were done by one of the investigators who lived in the village throughout the study, and who was well known and socially accepted by the experimental subjects. It is felt that the investigator's presence did not influence the subjects' pattern of physical activity.

Duration of the Study

Observations were done over a period of 16 months, during the planting season. the coffee harvest season, and between the harvest and the following planting season.

Indicators and Measurements

Anthropometry: Body weight and other anthropometric measurements were done after the energy cost of the various activities had been determined. In the longitudinal study, women were measured at monthly intervals, in the morning, before breakfast.

Energy cost of work: After observing the chores performed by each woman for 1 to 2 months, the most common tasks were identified (table 1). The energy cost of 21 such activities was measured by indirect calorimetry using a respiratory face-mask with a low-resistance valve, and either a portable respirometer of the Kofranyi-Michaelis type or a modification of the Douglas bag technique. For the latter, latex rubber balloons were used and exhaled air was measured with a dry-gas meter calibrated with a 600-litre Tissot gasometer. All volumes were adjusted to standard pressure, temperature, and humidity conditions (STPD). Oxygen concentrations were measured with a "microfuel cell" analyser (Teledyne, Inc., San Gabriel, California) calibrated with certified gases. Respiratory quotients of 0.88-0.90 were assumed for mild and moderate physical activity. and an energy equivalent of 4.92 kcal/litre oxygen, STPD, was used to calculate energy expenditure. The energy costs of eleven tasks were estimated from direct observations of their activity components and from calculations of the energy cost of those components (table 2).

TABLE 1. Energy Cost of Tasks Performed by Rural Women in Guatemala

TABLE 2. Energy Cost of Tasks Estimated from their Component Activities

a. The tasks are described in detail in the Appendix.

Time-motion observations: The 18 women in the longitudinal study were under direct observation by the same investigator twice in each of the three agricultural seasons. Observations were done on two different weekdays, within 10 days of each other, for 12 hours each day between 5 a.m. and 5 p.m. Each activity was described in a written record and timed with a stop-watch to the closest second.

Total energy expenditure: This was calculated from the time-motion and energy cost of work during 10 hours of the day and from questioning the women about their activities during the remaining 14 hours. The energy expended during the wakeful hours of that period was calculated as the average cost of cooking, caring for children, and resting (0.0313 kcal/kg/min.), or as the average cost of those three tasks plus that of washing clothes (0.0357 kcal/kg/min). The energy cost of the sleeping hours was estimated from the FAO/WHO 1973 recommendations (0.0164 kcal/kg/min).

Dietary surveys: During each of the three agricultural seasons, the dietary intake of each individual woman was calculated from 24-hour recall surveys and weighing of sample portions of food with a diet scale. The nutrient contents of foods were calculated from the Central American food-composition tables. Food samples were subjected to proximal analysis to confirm the adequacy of the use of the food-composition tables.

Summary of Main Results

Energy Cost of Tasks

Tables 1 and 2 show the energy cost of the 32 tasks that were used to calculate energy expenditure. Several activities were measured in pregnant, lactating, and NPNL women. There were no differences related to the physiological status in terms of units of body weight (i.e. kcal/kg). Pregnant women, however, expended more energy per unit of time in those activities that involved body displacement because they weighed more than NPNL or lactating women.

Longitudinal Study

Complete data were obtained from eleven women. Seven participated for only 6 to 10 months, mainly because of migration.

Anthropometry

Table 3 shows the anthropometric characteristics of the 11 women who participated throughout the study. Seven women who became pregnant and delivered a baby during the study did not gain weight during the first trimester of pregnancy. Mean weight gain during pregnancy was 6.9 + 3.1 kg (CV = 46 per cent). Weight gains during the second and third trimester of pregnancy were similar for the group of seven women, averaging 40 g/day. There were no significant seasonal changes in body weight or other anthropometric measurements, such as subcutaneous skinfold thicknesses or limb circumferences.

Pattern of Activities

The coffee harvest during the year of the study was the poorest for several years because of climatic conditions. This resulted in lower participation of women in agricultural tasks than customary in good harvest seasons. Consequently, most of the coffee was picked by the men in the village and the women devoted less time to agricultural chores than in previous years during the harvest season. This factor did not allow comparison of the activity pattern in harvest season with that in other seasons that would be typical of the agricultural cycle in other years.

TABLE 3. Anthropometric Characteristics of 11 Women (Average of Observations Made Over a Period of 16 Months)

TABLE 4. Daily Intake of Dietary Energy and Protein

a. Number of surveys
b. Unusually poor coffee harvest.

Dietary Intake

There were no differences between the family dietary surveys of the 18 women's families and the remainder of the village families, all of whom were also surveyed. The protein and energy intakes of the women, based on individual dietary surveys, are shown in table 4. No seasonal variations were detected, and there were no changes related to the women's physiological status.

Total Energy Expenditure

Table 5 shows the daily energy expenditure of the women. Each value used for each woman was the average of two-day observations carried out within a 10-day interval. No seasonal differences were detected.

TABLE 5. Daily Energy Expenditure Estimated by Time-Motion Studies in 18 Women (Mean ± SD)

Women who were pregnant expended more energy than when they were lactating, mainly because of greater weight during pregnancy, which implied more energy expenditure when they moved. These calculations did not take into account energy losses in milk secretion. Other studies at INCAP have shown that lactating women of similar socio-cultural and nutritional backgrounds produce 400 to 800 ml of breast milk per day during the first six months of lactation, with an average energy content of about 400 kcal/day.

Conclusions and Comments

The daily energy expenditure of the women studied was about 2,000 kcal/day, or 41 kcal/kg/day, without including the energy in milk secreted by lactating women. No differences were detected among the main agricultural seasons, but this may have been because of the poor coffee harvest during the year of the study.

When expressed per kg body weight, there were no differences between pregnant, lactating, or NPNL women in the energy cost of various activities or in their daily energy expenditure.

Dietary intake was estimated at about 200 kcal/day lower than the total energy expenditure (about 600 kcal lower for lactating women, assuming 400 kcal secreted in milk). This apparently "negative" energy balance was not accompanied by consistent weight reductions, except for lactating women, who usually reached their pre-pregnancy weights after two to three months of lactation. These discrepancies could be due to underestimations of intake, which are known to occur in many dietary surveys, to overestimations of expenditure, which could be errors in the time-motion studies and/or the energy equivalent of oxygen used to convert oxygen consumption into energy expenditure, or to a combination of both.

Weight gain during pregnancy was low (about 7 kg), which is consistent with other observations done at INCAP on women from rural Guatemala. Weight gain began in the second trimester of pregnancy and it seemed to proceed in a linear fashion in the last 160-180 days before delivery.

Acknowledgments

The authors express their gratitude to the people of Cacahuito, to Mr. Ruben D. Mendoza, Drs. Fernando Viteri, Alfonso Mata, Lic. Rafael Flores, Mr. Victor Manuel Luna, and the rest of the staff of INCAP's programme on nutrition and productivity, and to Dr. Peter Russell from INCAP's computer centre. This study was done with partial support from M.l.T.'s Department of Nutrition and Food Science, the Government of Guatemala, and the Kellogg Foundation.

Appendix

Energy expenditure was measured or estimated for the following activities and tasks, listed in alphabetical order:

Buying and selling: carrying out negotiations while standing; this often included walking a few steps.

Carrying loads. on the head, with the arms, or both; differences in the manner of carrying the load were minimal and values were therefore combined. The weight carried was added to the woman's weight to calculate energy expenditure per kg of body weight.

Child care: bathing, changing, and dressing children and helping them to move about.

Chopping wood: wood 2 to 4 inches in diameter and dried tree branches were chopped with a machete (long-blade knife weighing 2-3 lb); only the actual cost of chopping was measured.

Cooking: over wood fires using virtually no labour-saving devices. Typical activities included cutting of vegetables or meat; preparing and cooking rice, beans, or corn (which entailed walking within the house to get the grain, walking to an outside water-tap to draw water, apportioning grain or water, carrying the pot to the fire, stoking and poking the fire), and cleaning counters or a table. Environmental temperature in the kitchen was usually 27°C or higher.

Cutting fruit with a pole: a long pole was lifted and swung at fruit hanging from high branches. The woman then picked the fallen fruit from the ground and placed them in a basket which was carried to the next tree.

Eating: seated at a table the majority of the time, occasionally getting up to serve food to family members.

Gleaning. encompassed several activities - gathering wild fruit in the woods, scavenging fallen coffee berries for the household and gleaning grains after thrashing rice, sorghum, or beans. This activity also included the picking of low plants or chili peppers and involved frequent crouching.

Hanging clothes: draping wet clothes over a line, bushes. or on rooftops and removing them when dry.

House-cleaning: this is a general category for household duties that accounts for a large portion of the women's work-day. It included dusting, folding clothes, shaking out straw sleeping mats, collecting clothes for washing, and "putting things in order." It can be considered as "random standing," as more standing than walking was involved.

Ironing clothes: was performed while standing, using a coal-filled or coal-heated iron.

Lifting and moving: activities such as stacking firewood, placing beans to dry under the sun, and moving furniture and other household objects.

Light work with a machete: cutting low brush, usually to clear a trail while walking through fields.

Lying down: energy expenditure was measured after 15 minutes in this position.

Making tortillas: included kneading of corn-dough and adding water until smooth; rolling the dough on a grinding stone; patting a small amount of dough with both hands into a round, thin pancake; tending the tortillas while they cooked on a griddle, and poking and stoking the fire. The grinding stones and fire were often located on opposite sides of the room and the process included frequent walking across the kitchen.

Nursing: usually while seated. When performing simultaneously other activities such as cooking or housecleaning, the energy cost of the most demanding activity was used to calculate energy expenditure.

Personal necessities: dressing and undressing, hair-combing, bathing, and walking to an "out-house" to urinate or defecate.

Picking coffee: coffee berries were picked from branches within arm's reach of women standing beside the trees. Berries were placed in a basket tied to the women's waists and carried from tree to tree until the basket was full. The contents of full baskets (about 35 lb) were dumped into a gunny-sack. Generally, coffee plantations were located on fairly flat terrain. The measurements made in this study coincided with a poor coffee harvest; during good seasons coffee is picked faster and in larger amounts per working hour.

Picking fruit: fruit, nuts, and leaves from bushes and trees within reach were picked while standing.

Raking and burning: raking leaves, grass, litter, and trash into a heap for burning.

Sitting and sewing: these activities were combined, as women sewed while seated and energy expenditure was similar to that of non-activity.

Standing: either unsupported or while leaning against a wall.

Staking a fence: cutting saplings with a machete, digging holes with a stick, securing poles into the ground, and tying fence wires round the poles.

Sweeping: with a broom. Earth floors of the houses were sprinkled with water prior to sweeping.

Tending animals: herding pigs and cows short distances; preparing a slop of corn dough, water, and salt and pouring it into a trough, and scattering grain for fowl.

Walking: was measured on local terrain, while ascending and descending mild slopes or on a flat surface. Generally, the women walked at a pace of about 4 km per hour.

Washing dishes: included lifting full buckets of water and vigorous scrubbing with coarse sand to remove grease and particles from pans and dishes.

Washing clothes. by hand, either in a concrete sink with a textured scrubbing surface or at a river. The rinsing of clothes was performed at the sink by scooping water and pouring it over the soaped clothes, whereas at the river clothing was dunked several times into the current. The women worked less continuously at the sink to allow for re-filling of the water-tank. Nevertheless, there was no difference in the amounts of energy expended using either method. Dirt was removed from the clothes by the women's physical force and weight against the roughness of the sink's surface or the rocks in the river; virtually no detergent and only mild vegetable soaps were used. The procedure consisted of wetting the clothes, soaping, scrubbing (anchoring the cloth with one hand and scrubbing with a back-and-forth motion using the others, rinsing and wringing; with heavy or exceptionally dirty clothing, both hands were used to scrub and the procedure was akin to kneading a tough piece of dough.

Weeding: stooping to cut weeds with a small curved knife, between bean plants or rows of corn.

Winnowing and other grain preparation performed while seated. This included shucking corn and removing dried kernels, cleaning undesirable particles from the grain, shaking or blowing grains to remove extraneous matter, shelling beans, separating grains for planting from those for eating, and winnowing by pouring the grain into the wind for cleaning.

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