For the first time the IAEA is to help United Nations nutrition experts reevaluate human energy requirements: a key input for assessing global hunger that was last evaluated in 2001.
The IAEA will provide expertise and data based on nuclear science, to address knowledge gaps in how calorie and nutrition requirements are understood and calculated, in partnership with the Food and Agriculture Organization of the United Nations (FAO), the World Health Organization (WHO) and others.
"Energy requirements are an important input into calculations used for SDG2 (Zero Hunger) reporting, specifically undernourishment. It is very important that we periodically review the basis for these calculations and reflect on whether updates are needed," said Lynnette Neufeld, Director of FAO's Food and Nutrition Division.
With more than 700 million men, women and children going hungry last year, ending hunger, food insecurity and malnutrition in time to achieve the 2030 Agenda will remain out of reach without more and better targeted efforts. Undernutrition in particular - a form of malnutrition which includes wasting, stunting, underweight and vitamin and mineral deficiencies - continues to be a pressing challenge outlined in the United Nations' recently launched report on The State of Food Security and Nutrition in the World (SOFI 2024). If current trends continue, a projected 528 million people will be chronically undernourished by the decade's end. Yet, to ensure effective action, policies and interventions must be informed by accurate data. To that end, the IAEA, FAO and WHO and other global experts reviewed current scientific understandings of human energy requirements at a consultancy meeting held at the IAEA's Vienna headquarters in June.
These children in Mauritius are taking part in nutrition research using nuclear science. (Photo: J. Weilguny/IAEA)
Energy requirements reflect what an individual needs to maintain all bodily functions, including growth and development, depending on life stage as well as activity for long-term health, and are essential for evaluating how well food supplies can meet the nutritional demands of a population. These requirements vary in relation to a person's age, gender, physiological status (e.g., pregnancy), level of physical activity, basal metabolic rate (BMR) (the amount of energy needed for basic life functions such as breathing and keeping the body temperature) and environment, to name a few factors. For certain groups, they encompass additional energy costs such as optimal growth in the case of children; tissue development in pregnant women; and milk production in lactating mothers. Estimating accurate energy requirements can consequently entail complex calculations and challenges - especially when attempting to do so for specific sub-populations around the globe.
As early as the 1950s, the FAO and WHO collaborated with global nutrition specialists to assess energy requirements and, in turn, derive these estimates. Their most recent exercise in October 2001 notably developed key recommendations for specific groups. It also maintained the use of international calculations first developed in 1985 (Schofield's equations) to estimate BMR based on a person's gender, age, weight and physical activity level. However, in the decades that have since elapsed, the field has seen a growing body of scientific evidence which challenges the adequacy and accuracy of some aspects of those equations for universal use.
Discussing FAO's seminal 2004 report on the topic, the meeting's 15 nutrition and energy metabolism experts noted a number of developments affecting BMR: the dramatic increase in global obesity; documented variations in metabolically active tissues across different populations; and trends - specifically declines - in the amount of energy needed for essential bodily functions. They also identified several key data gaps, especially those concerning energy requirements of underrepresented populations in low- and middle-income countries (LMICs); people over 90; and pregnant and lactating women. Experts formulated a roadmap which outlined next steps to update estimates of energy requirement while suggesting areas for future research.
"A correct estimate of energy needs at different ages is needed to plan for actions to prevent and manage different forms of malnutrition. The update may help us reconsider the design of population programmes in LMICs," said Francesco Branca, Director of WHO's Department of Nutrition and Food Safety.
The IAEA's Doubly Labelled Water (DLW) Database has been used by scientists to redefine understandings of human energy metabolism. (Photo: IAEA)
The IAEA can help revise energy requirements by providing data. Its Doubly Labelled Water (DLW) Database - a collection of almost 12 000 measurements of daily energy expenditure from pre-term infants to nonagenarians spanning 40 countries - has already been utilised by researchers and scientists around the world to generate scientific publications redefining understandings of human energy metabolism. The IAEA can also help address additional knowledge gaps on specific population groups and regions. A 2022 coordinated research project, for example, is gathering additional data on energy expenditure for pre-adolescents and adolescents in LMICs.
"Going forward, all three United Nations agencies will continue their global consultations by including dietitians, clinicians and other public health related end users. As an immediate next step, the meeting's participants will collaborate on a series of papers highlighting the need for a paradigm shift within human energy requirements," said Cornelia Loechl, Head of the Nutritional and Health-Related Environmental Studies Section in the IAEA's Division of Human Health.
