Estimation of non-shivering thermogenesis and cold-induced nutrient oxidation rates: Impact of method for data selection and analysis

• Published in: Clinical nutrition (Edinburgh, Scotland) Scotland), 2019-10, Vol.38 (5), p.2168-2174
• Main Authors: Sanchez-Delgado, Guillermo, Alcantara, Juan M.A., Acosta, Francisco M., Martinez-Tellez, Borja, Amaro-Gahete, Francisco J., Ortiz-Alvarez, Lourdes, Löf, Marie, Labayen, Idoia, Ruiz, Jonatan R.
• Format: Article
• Language: English
• Subjects: Adaptive thermogenesis; Cold-induced thermogenesis; Energy balance; Indirect calorimetry; Medicin och hälsovetenskap; Metabolic rate; Obesity
• ISSN: 0261-5614; 1532-1983; 1532-1983
• DOI: 10.1016/j.clnu.2018.09.009

Since the discovery of active brown adipose tissue in human adults, non-shivering cold-induced thermogenesis (CIT) has been regarded as a promising tool to combat obesity. However, there is a lack of consensus regarding the method of choice to analyze indirect calorimetry data from a CIT study. We analyzed the impact of methods for data selection and methods for data analysis on measures of cold-induced energy expenditure (EE) and nutrient oxidation rates. Forty-four young healthy adults (22.1 ± 2.1 years old, 25.6 ± 5.2 kg/m2, 29 women) participated in the study. Resting metabolic rate (RMR), cold-induced thermogenesis (CIT), and cold-induced nutrient oxidation rates were estimated by indirect calorimetry under fasting conditions during 1 h of cold exposure combining air conditioning (19.5–20 °C) and a water perfused cooling vest set at a temperature of 4 °C above the individual shivering threshold. We applied three methods for data selection: (i) time intervals every 5 min (5min-TI), (ii) the most stable 5-min period of every forth part of the cold exposure (5min-SS-4P), and (iii) the most stable 5-min period of every half part of the cold exposure (5min-SS-2P). Lately we applied two methods for data analysis: (i) area under the curve as a percentage of the baseline RMR (AUC) and; (ii) the difference between EE at the end of the cold exposure and baseline RMR (Last-RMR). Mean overall CIT estimation ranged from 11.6 ± 10.0 to 20.1 ± 17.2 %RMR depending on the methods for data selection and analysis used. Regarding methods for data selection, 5min-SS-2P did not allow to observe physiologically relevant phenomena (e.g. metabolic shift in fuel oxidation; P = 0.547) due to a lack of resolution. The 5min-TI and 5min-SS-4P methods for data selection seemed to be accurate enough to observe physiologically relevant phenomena (all P