ETIOLOGY OF OBESITY (T GILL, SECTION EDITOR) Issues in Measuring and Interpreting Energy Balance and Its Contribution to Obesity Rodrigo Fernández-Verdejo 1 & Carolina Aguirre 1 & Jose E. Galgani 1,2 # Springer Science+Business Media, LLC, part of Springer Nature 2019 Abstract Purpose of Review Obesogenic environment challenges individuals’ ability to preserve energy homeostasis, leading to weight gain. To understand how this energy imbalance proceeds, several methods and analytical procedures to determine energy intake and expenditure are currently available. However, these methods and procedures are not exempt from issues that may lead to equivocal conclusions. Our purpose herein is to discuss major issues involved in energy balance assessment. Recent Findings Measurement of energy intake mostly relies on self-report methods that provide inaccurate data. In contrast, determination of energy expenditure is more accurate as long as methodological and analytical issues are correctly addressed. Summary Accurate measurements of energy expenditure can be obtained with the current methods once issues in measuring and interpreting data are correctly addressed. However, development of new technologies to measure energy intake is imperative to further understand the small and chronic energy imbalance leading to obesity. Keywords Energy expenditure . Carbohydrate balance . Body composition . Indirect calorimetry . Metabolic rate Introduction A mismatch between energy intake and energy expendi- ture results in changes in body weight and composition. Due to the worldwide obesity pandemic, efforts have been made to determine which factors increase energy intake relative to expenditure. Special interest exists in identify- ing inter-individual factors that explain differential sus- ceptibility to weight gain. For this purpose, reliable as- sessment of energy intake and energy expenditure is es- sential. Several methods for the assessment of these com- ponents are available. Each method carries issues that, if not considered, may lead to equivocal results and inter- pretations. Our aim is to discuss the main issues in measuring and interpreting energy intake and expenditure in the context of human obesity. Energy Intake Recall of Food Eaten This approach quantitatively assesses recent food intake. The method usually comprises the collection of foods consumed during the last day [1]. Although easy to administer, the main issue is that a single 24-h recall may not reflect habitual intake. Thus, Ma et al. [2] recommended that three 24-h recalls should be applied to estimate energy intake. Because reported intake tends to be higher on weekends, a combination of weekdays and weekend is advised [2]. Food Records By weighing the food and drinks consumed over a time frame, usually 3–7 days, food records are considered the most accu- rate method of dietary assessment [3]. However, the trouble of weighing and recording intake over several days makes sub- jects to alter their dietary pattern as well as under-report their intake [4, 5]. This article is part of the Topical Collection on Etiology of Obesity * Jose E. Galgani jgalgani@uc.cl 1 Carrera de Nutrición y Dietética, Departamento de Ciencias de la Salud, Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile 2 Departamento de Nutrición, Diabetes y Metabolismo, Facultad de Medicina, Pontificia Universidad Católica de Chile, Avda. Libertador Bernardo O’Higgins 340, Santiago, Chile Current Obesity Reports https://doi.org/10.1007/s13679-019-00339-z