Dieting and over-eating - two potent issues at the heart of today's health driven society. One slice of the population - women - is particularly bombarded by images of the ideal weight. But exactly how much energy do they actually need to see them through an average day? Scientists in the US claim that current recommended daily caloric intakes need to be revised.
Led by Nancy F. Butte at the Agricultural Research Service's Children's Nutrition Research Center in Texas, researchers set out to determine the actual energy requirements of healthy underweight, normal-weight and overweight women of reproductive age. Their primary objective was to define the precise energy requirements of pregnant and lactating women, to best ensure good health for mothers and infants.
Researchers used the doubly labelled water method to measure total energy expenditure (TEE) in 116 women living in urban areas. The method measures energy expenditure and energy requirements of free-living individuals. Doubly labelled water, or heavy water, is a safe, non-radioactive form of water enriched with heavier forms of hydrogen and oxygen that are used to track end products of metabolism, water and carbon dioxide.
Volunteers followed their usual diet and activities. Thirteen possessed a low body mass index (BMI) - used to gauge body fat in adults - with 70 a normal BMI and 33 had high BMIs. A multi-component model was used to measure body fat.
The researchers measured the volunteers' 24-hour basal metabolic rate (BMR) and energy expenditure via a respiration calorimeter. In addition, they calculated physical activity levels by dividing volunteers' total energy expenditure, or TEE value, by their BMR values.
The researchers found that low-, normal- and high-BMI groups used varying amounts of energy, ranging from about 2,100 to 2,700 calories - 8.9 to 11.5 megajoules - per day. Their findings, questioning today's current recommendations, suggest that further research should be undertaken in order to establish a more appropriate figure. As millions of women struggle to obtain the 'right' image, more studies - government and privately-funded - must occur in order to establish a clearer idea of the precise energy needs of the female body.
Full findings are published in the March issue of the American Journal of Clinical Nutrition.