title: Is Obesity Associated with Altered Energy Expenditure?
abstract: Historically, obese individuals were believed to have lower energy expenditure (EE) rates than nonobese individuals (normal and overweight), which, in the long term, would contribute to a positive energy balance and subsequent weight gain. The aim of this review was to critically appraise studies that compared measures of EE and its components, resting EE (REE), activity EE (AEE), and diet-induced thermogenesis (DIT), in obese and nonobese adults to elucidate whether obesity is associated with altered EE. Contrary to popular belief, research has shown that obese individuals have higher absolute REE and total EE. When body composition (namely the metabolically active component, fat-free mass) is taken into account, these differences between obese and nonobese individuals disappear, suggesting that EE in obese individuals is not altered. However, an important question is whether AEE is lower in obese individuals because of a decrease in overall physical activity or because of less energy expended while performing physical activity. AEE and DIT could be reduced in obese individuals, mostly because of unhealthy behavior (low physical activity, higher intake of fat). However, the current evidence does not support the hypothesis that obesity is sustained by lower daily EE or REE. Future studies, comparing EE between obese and nonobese and assessing potential physiologic abnormalities in obese individuals, should be able to better answer the question of whether these individuals have altered energy metabolism.
authors.affiliation: Department of Agricultural, Food and Nutritional Science, Li Ka Shing Centre.
authors.forename: Isabella P
authors.initials: IP
authors.lastname: Carneiro
authors.affiliation: Department of Agricultural, Food and Nutritional Science, Li Ka Shing Centre.
authors.forename: Sarah A
authors.initials: SA
authors.lastname: Elliott
authors.affiliation: Human Nutrition Research Centre, Institute of Cellular Medicine, Newcastle University, Campus for Ageing and Vitality, Newcastle on Tyne, United Kingdom; and.
authors.forename: Mario
authors.initials: M
authors.lastname: Siervo
authors.affiliation: Department of Medicine, University of Alberta, Edmonton, Alberta, Canada;
authors.forename: Raj
authors.initials: R
authors.lastname: Padwal
authors.affiliation: International Center for the Assessment of Nutritional Status (ICANS), Department of Food, Environmental and Nutritional Sciences, University of Milan, Milano, Italy.
authors.forename: Simona
authors.initials: S
authors.lastname: Bertoli
authors.affiliation: International Center for the Assessment of Nutritional Status (ICANS), Department of Food, Environmental and Nutritional Sciences, University of Milan, Milano, Italy.
authors.forename: Alberto
authors.initials: A
authors.lastname: Battezzati
authors.affiliation: Department of Agricultural, Food and Nutritional Science, Li Ka Shing Centre, cprado@ualberta.ca.
authors.forename: Carla M
authors.initials: CM
authors.lastname: Prado
mesh_terms: D001481:Basal Metabolism; D001823:Body Composition; D015992:Body Mass Index; D004041:Dietary Fats / Q000378:metabolism; D004734:Energy Metabolism / Q000502:physiology*; D015444:Exercise / Q000502:physiology*; D006801:Humans; D009765:Obesity / Q000378:metabolism*; D012146:Rest / Q000502:physiology*; D057185:Sedentary Behavior; D015430:Weight Gain / Q000502:physiology*
chemical_list: D004041:Dietary Fats
keywords: activity energy expenditure; diet-induced thermogenesis; energy expenditure; energy metabolism; obesity; resting energy expenditure