Are therapeutic energy requirements overestimated?

In December 2023, the World Health Organization (WHO) published an updated guideline on the prevention and management of wasting and nutritional oedema (acute malnutrition) in infants and children under five years. This article delves into the use of ready-to-use therapeutic food (RUTF) for treatment of severe wasting and/or nutritional oedema (recommendation B10), debating the optimal dosage. The authors propose that instead of the recommended energy intake of 150-185 kcal/kg/day, an alternative calculation providing 105-120 kcal/kg/day should be considered. 

Firstly, the authors present the previous guidelines on caloric requirements and their evidence base. The 2013 WHO guideline recommended 100-135 kcal/kg/day in the rehabilitation phase (inpatient care) when transitioning from F75 (therapeutic milk) to therapeutic food and subsequently to outpatient care. However, the updated WHO guidance refers to the previously recommended standard quantity of RUTF of 150-220 kcal/kg/day. The authors flag that this caloric range probably stems from the 1999 and 2003 guidelines that pertained to therapeutic milks rather than more energy-dense solid RUTF. 

The 2023 recommendation is based on measured resting energy expenditure (REE), along with assumed values for factors related to physical activity, clinical stress, growth, and absorption. Despite the rationale outlined by the guideline development group, the authors highlight some concerns about this calculation. These include the likely double counting of clinical stress, which is already assumed to a degree in REE, depending on disease state, prior wasting, and the presence of fever and then applied as a constant factor. Simultaneously adding physical activity, catch-up growth, and/or clinical stress factors is also likely to result in overestimations. For example, if the child is sick and lying in bed, no – or only a minimal – physical activity factor should be applied to the REE. 

Finally, the target weight gain of 5-10 g/kg/day is largely informed by inpatient clinical trials and calculations. There is strong evidence from community-based settings in support of a targeted weight gain of 4-5g/kg/day but none that supports 10g/kg/day. The recommended caloric range outlined in this article is based on three scenarios and is compared against several studies where lower kcal/kg/day were used with no adverse effects on recovery or mortality. 

The authors suggest that there could be adverse consequences because of caloric overfeeding. Notably they point out the association of faster weight gain with increased liver fat, waist circumference, and adiposity in later life, and increased energy intake with dyslipidaemia. They also argue that there are gaps in practical guidance in the 2023 guideline such as when and how to transition to home-based diets, and what the maximal duration of therapeutic feeding should be. With reviews of national guidelines ongoing, it is important that the questions posed in this article are answered. Read more about this debate in this issue in the views piece by Lelijveld et al.