Even though sub-Saharan African women spend millions of person-hours per day fetching water and pounding grain, to date, few studies have rigorously assessed the energy expenditure costs of such domestic activities. As a result, most analyses that consider head-hauling water or hand pounding of grain with a mortar and pestle (pilão use) employ energy expenditure values derived from limited research. The current paper compares estimated energy expenditure values from heart rate monitors v. indirect calorimetry in order to understand some of the limitations with using such monitors to measure domestic activities.

This confirmation study estimates the metabolic equivalent of task (MET) value for head-hauling water and hand-pounding grain using both indirect calorimetry and heart rate monitors under laboratory conditions.

The study was conducted in Nampula, Mozambique.

Forty university students in Nampula city who recurrently engaged in water-fetching activities.

Including all participants, the mean MET value for head hauling 20 litres (20·5 kg, including container) of water (2·7 km/h, 0 % slope) was 4·3 (sd 0·9) and 3·7 (sd 1·2) for pilão use. Estimated energy expenditure predictions from a mixed model were found to correlate with observed energy expenditure (r2 0·68, r 0·82). Re-estimating the model with pilão use data excluded improved the fit substantially (r2 0·83, r 0·91).

The current study finds that heart rate monitors are suitable instruments for providing accurate quantification of energy expenditure for some domestic activities, such as head-hauling water, but are not appropriate for quantifying expenditures of other activities, such as hand-pounding grain.

To examine the association between energy density and energy costs in single food items and composed diets, and to explore differences in energy density and energy cost between income levels.

A cross-sectional study using data from two Dutch cohort studies and recent national food prices. Food prices were retrieved from two market leader supermarkets. Data on dietary intake were measured using a computerized face-to-face interview (cohort 1) and 24 h recalls (cohort 2).

The Netherlands.

A sample of 373 young adults from the Amsterdam Growth and Health Longitudinal Study (AGHLS, measured in 2000) and a sample of 200 community-dwelling elderly from the Longitudinal Ageing Study Amsterdam (LASA, measured in 2007).

We found significant inverse associations between energy density and energy costs in single food items (r = −0·436, P < 0·01) and composed diets (AGHLS men r = −0·505, women r = −0·413, P < 0·001; LASA men r = −0·559, women r = −0·562, P < 0·001). Furthermore, we found that people stratified into higher energy density quartiles consumed significantly more energy per day, less fruits and vegetables, and had significantly lower diet costs. Explorative analyses on income did not reveal significant differences regarding energy density, costs, or fruit and vegetable intake.

In the Netherlands also, energy density was inversely related with energy costs, implying that healthier diets cost more. However, we could not find differences in energy density or costs between income levels. Future research, using precise food expenditures, is of main importance in studying the economics of obesity and in the aim of making the healthier choice easier.

In view of the paucity of data on energy costs, the present study aimed to estimate these for typical daily activities performed by women in rural India.

A cross-sectional study covering 26 different activities was done by indirect calorimetry using the Oxylog™ instrument (Morgan).

Villages about 30–40 km from Pune city, Maharashtra, India.

Energy costs were measured on 22 rural Indian women aged 18–45 years.

Irrespective of whether an activity was domestic or farming, energy cost was lower when performed in sitting position (cleaning grains 5.24 kJ min−1, plucking leafy vegetables 5.76 kJ min−1) and increased considerably with the extent of muscular movement (carrying two water containers 14.77 kJ min−1, chopping firewood 14.5 kJ min−1), indicating the importance of the postural details of the activity. Physical activity ratio computed using the Food and Agriculture Organization/World Health Organization/United Nations University equation (PARw) was lower for all activities compared with that (PARm) based on measured basal metabolic rate, indicating the need for a population-specific equation. Furthermore, PARw identified more activities as belonging to the ‘very light’ category (nine out of 26 activities), in contrast to the perception of rural women which was supported with empirical evidence. Estimated daily energy expenditure of the women was 7.69 ± 0.63 MJ (1837 ± 150 kcal) and identified their daily activity pattern as ‘moderate’ based on PALw (1.65 ± 0.16) while PALm (2.04 ± 0.18) identified it as ‘heavy’.

Our results highlight the importance of qualitative descriptions of the various activities. The energy costs for several daily activities reported in this study could potentially be used for estimating daily energy expenditure of women from similar rural settings.