Objective: Human brown adipose tissue (BAT) has gained considerable attention as a potential therapeutic target for obesity and its related cardiometabolic diseases; however, whether the gut... Show moreObjective: Human brown adipose tissue (BAT) has gained considerable attention as a potential therapeutic target for obesity and its related cardiometabolic diseases; however, whether the gut microbiota might be an efficient stimulus to activate BAT metabolism remains to be ascertained. We aimed to investigate the association of fecal microbiota composition with BAT volume and activity and mean radiodensity in young adults. Methods: 82 young adults (58 women, 21.8 +/- 2.2 years old) participated in this cross-sectional study. DNA was extracted from fecal samples and 16S rRNA sequencing was performed to analyse the fecal microbiota composition. BAT was determined via a static F-18-fluorodeoxyglucose (F-18-FDG) positron emission tomography-computed tomography scan (PET/CT) after a 2 h personalized cooling protocol. F-18-FDG uptake was also quantified in white adipose tissue (WAT) and skeletal muscles. Results: The relative abundance of Akkermansia, Lachnospiraceae sp. and Ruminococcus genera was negatively correlated with BAT volume, BAT SUVmean and BAT SUVpeak (all rho <= - 0.232, P <= 0.027), whereas the relative abundance of Bifidobacterium genus was positively correlated with BAT SUVmean and BAT SUVpeak (all rho >= 0.262, P <= 0.012). On the other hand, the relative abundance of Sutterellaceae and Bifidobacteriaceae families was positively correlated with F-18-FDG uptake by WAT and skeletal muscles (all rho >= 0.213, P <= 0.042). All the analyses were adjusted for the PET/CT scan date as a proxy of seasonality. Conclusion: Our results suggest that fecal microbiota composition is involved in the regulation of BAT and glucose uptake by other tissues in young adults. Further studies are needed to confirm these findings. Show less
Exercise modulates both brown adipose tissue (BAT) metabolism and white adipose tissue (WAT) browning in murine models. Whether this is true in humans, however, has remained unknown. An unblinded... Show moreExercise modulates both brown adipose tissue (BAT) metabolism and white adipose tissue (WAT) browning in murine models. Whether this is true in humans, however, has remained unknown. An unblinded randomized controlled trial (ClinicalTrials.gov ID: NCT02365129) was therefore conducted to study the effects of a 24-week supervised exercise intervention, combining endurance and resistance training, on BAT volume and activity (primary outcome). The study was carried out in the Sport and Health University Research Institute and the Virgen de las Nieves University Hospital of the University of Granada (Spain). One hundred and forty-five young sedentary adults were assigned to either (i) a control group (no exercise, n = 54), (ii) a moderate intensity exercise group (MOD-EX, n = 48), or (iii) a vigorous intensity exercise group (VIG-EX n = 43) by unrestricted randomization. No relevant adverse events were recorded. 97 participants (34 men, 63 women) were included in the final analysis (Control; n = 35, MOD-EX; n = 31, and VIG-EX; n = 31). We observed no changes in BAT volume (Delta Control: -22.2 +/- 52.6 ml; Delta MOD-EX: -15.5 +/- 62.1 ml, Delta VIG-EX: -6.8 +/- 66.4 ml; P = 0.771) or F-18-fluorodeoxyglucose uptake (SUVpeak Delta Control: -2.6 +/- 3.1 ml; Delta MOD-EX: -1.2 +/- 4.8, Delta VIG-EX: -2.2 +/- 5.1; p = 0.476) in either the control or the exercise groups. Thus, we did not find any evidence of an exercise-induced change on BAT volume or activity in young sedentary adults.Exercise modulates brown adipose tissue (BAT) metabolism in murine models. Here the authors report that there is no evidence that 24 weeks of supervised exercise training modulates BAT volume or function in young sedentary adults in the ACTIBATE randomized controlled trial. Show less
Objective: To study the association between usual dietary factors (dietary energy density, nutrient intake, food group consumption, and dietary pattern) and brown adipose tissue (BAT) volume/F-18... Show moreObjective: To study the association between usual dietary factors (dietary energy density, nutrient intake, food group consumption, and dietary pattern) and brown adipose tissue (BAT) volume/F-18-fluorodeoxyglucose (F-18-FDG) uptake after personalized cold exposure in young healthy adults.Methods: A total of 122 young adults (n = 82 women; 22.0 +/- 2.1 years old; 24.8 +/- 4.8 kg/m(2)) took part in this cross-sectional study. Dietary factors were measured via a food frequency questionnaire and three non-consecutive 24 h recalls. Dietary energy density (foods and caloric beverages included) and macronutrient intakes were subsequently estimated using EvaIFINUT (R) software, food group consumption was estimated from the food frequency questionnaire, and different dietary patterns and quality indices were determined according to the reference methods. BAT volume, BAT F-18-FDG uptake, and skeletal muscle F-18-FDG uptake were assessed by static F-18-FDG positron-emission tomography and computed tomography (PET-CT) scans after a 2 h personalized exposure to cold.Results: A direct association was detected between dietary energy density and BAT Standardized Uptake Value (SUV)mean (beta = 0.215; R-2 = 0.044; P = 0.022), and between ethanol consumption and BAT volume (beta = 0.215; R-2 = 0.044; P = 0.022). The a priori Mediterranean dietary pattern was inversely associated with BAT SUVmean and SUVpeak (beta = -0.273; R-2 = 0.075; P = 0.003 and beta = -0.255; R-2 = 0.066; P = 0.005 respectively). In addition, the diet quality index for a Mediterranean diet and a pro-inflammatory dietary pattern (as determined via the dietary inflammatory index) were directly associated with BAT SUVmean and SUVpeak (SUVmean: beta = 0.238; R-2 = 0.053; P = 0.013 and beta = 0.256; R-2 = 0.052; P = 0.012 respectively; SUVpeak: beta = 0.278; R-2 = 0.073; P = 0.003 and beta = 0.248; R-2 = 0.049; P = 0.016 respectively). After controlling for multiplicity and possible confounders (sex, the evaluation wave and BMI), all the detected associations persisted.Conclusion: Dietary factors are slightly associated with BAT volume and/or F-18-FDG uptake after a personalized cold exposure in young adults. Our results provide an overall picture of the potential relationships between dietary factors and BAT-related variables in humans. (C) 2020 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved. Show less
Objective This study aimed to describe the energy expenditure (EE) and macronutrient oxidation response to an individualized nonshivering cold exposure in young healthy adults. Methods Two... Show moreObjective This study aimed to describe the energy expenditure (EE) and macronutrient oxidation response to an individualized nonshivering cold exposure in young healthy adults. Methods Two different groups of 44 (study 1: 22.1 [SD 2.1] years old, 25.6 [SD 5.2] kg/m(2), 34% men) and 13 young healthy adults (study 2: 25.6 [SD 3.0] years old, 23.6 [SD 2.4] kg/m(2), 54% men) participated in this study. Resting metabolic rate (RMR) and macronutrient oxidation rates were measured by indirect calorimetry under fasting conditions in a warm environment (for 30 minutes) and in mild cold conditions (for 65 minutes, with the individual wearing a water-perfused cooling vest set at an individualized temperature adjusted to the individual's shivering threshold). Results In study 1, EE increased in the initial stage of cold exposure and remained stable for the whole cold exposure (P < 0.001). Mean cold-induced thermogenesis (9.56 +/- 7.9 kcal/h) was 13.9% +/- 11.6% of the RMR (range: -14.8% to 39.9% of the RMR). Carbohydrate oxidation decreased during the first 30 minutes of the cold exposure and later recovered up to the baseline values (P < 0.01) in parallel to opposite changes in fat oxidation (P < 0.01). Results were replicated in study 2. Conclusions A 1-hour mild cold exposure individually adjusted to elicit maximum nonshivering thermogenesis induces a very modest increase in EE and a shift of macronutrient oxidation that may underlie a shift in thermogenic tissue activity. Show less
Background: Several studies have explored the role of human brown adipose tissue (BAT) in energy expenditure. However, the link between BAT and appetite regulation needs to be more rigorously... Show moreBackground: Several studies have explored the role of human brown adipose tissue (BAT) in energy expenditure. However, the link between BAT and appetite regulation needs to be more rigorously examined.Objective: We aimed to investigate the associations of BAT volume and F-18-fluordeoxyglucose (F-18-FDG) uptake after a personalized cold exposure with energy intake and appetite-related sensations in young healthy humans.Methods: A total of 102 young adults (65 women; age: 22.08 +/- 2.17 y; BMI: 25.05 +/- 4.93 kg/m(2)) took part in this cross-sectional study. BAT volume, BAT F-18-FDG uptake, and skeletal muscle F-18-FDG uptake were assessed by means of static F-18-FDG positron-emission tomography and computed tomography scans after a 2-h personalized exposure to cold. Energy intake was estimated via an objectively measured ad libitum meal and three nonconsecutive 24-h dietary recalls. Appetite-related sensations (i.e., hunger and fullness) were recorded by visual analog scales before and after a standardized breakfast (energy content = 50% of basal metabolic rate) and the ad libitum meal. Body composition was assessed by a whole-body DXA scan.Results: BAT volume and F-18-FDG uptake were not associated with quantified ad libitum energy intake (all P > 0.088), nor with habitual energy intake estimated from the 24-h dietary recalls (all P > 0.683). Lean mass was positively associated with both the energy intake from the ad libitum meal (beta: 17.612, R-2 = 0.213; P < 0.001) and the habitual energy intake (beta: 16.052, R-2 = 0.123; P = 0.001). Neither the interaction BAT volume x time elapsed after meal consumption nor that of BAT F-18-FDG uptake x time elapsed after meal consumption had any significant influence on appetite-related sensations after breakfast or after meal consumption (all P > 0.3).Conclusions: Neither BAT volume, nor BAT F-18-FDG uptake after cold stimulation, are related to appetite regulation in young adults. These results suggest BAT plays no important role in the regulation of energy intake in humans. This trial was registered at clinicaltrials.gov as NCT02365129. Show less
Background & aims: 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.... Show moreBackground & aims: 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.Methods: Forty-four young healthy adults (22.1 +/- 2.1 years old, 25.6 +/- 5.2 kg/m(2), 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 degrees C) and a water perfused cooling vest set at a temperature of 4 degrees 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).Results: 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 < 0.014), but not comparable for estimating over-all CIT and cold-induced nutrient oxidation rates (P < 0.01). Regarding methods for data analysis, the AUC seemed to be less affected for data artefacts and to be more representative in participants with a non-stable energy expenditure during cold exposure.Conclusions: The methods for data selection and analysis can have a profound impact on CIT and cold-induced nutrient oxidation rates estimations, and therefore, it is mandatory to unify it across scientific community to allow inter-study comparisons. Based on our findings, 5min-TI should be considered the method of choice to study dynamics (i.e. changes across time) of CIT and cold-induced nutrient oxidation rates, while 5min-SS-4P and AUC should be the method of choice when computing CIT and cold-induced nutrient oxidation rates as a single value. (C) 2018 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved. Show less
The time spent in sedentary behaviour represents an important public health burden. To reduce sedentary time in the general population, the simplest, most effective, and most accessible method is... Show moreThe time spent in sedentary behaviour represents an important public health burden. To reduce sedentary time in the general population, the simplest, most effective, and most accessible method is to decrease lying and sitting time. We aimed to compare differences on energy expenditure (EE) across lying, sitting, and standing positions; and to analyse the associations between the change on EE of changing from one position to another and anthropometric and body composition parameters in young healthy adults. A total of 55 (69% women) young healthy adults aged 21.7 +/- 2.2 participated in the study. We measured EE by indirect calorimetry across lying, sitting, and standing positions following the standard procedures. The EE was significantly higher in standing than in both lying and sitting positions (mean difference: 0.121 +/- 0.292 and 0.125 +/- 0.241 kcal/min, respectively; all P<0.001), and no differences were observed between lying and sitting positions (P = 1.000). There was a negative association between the EE differences in sitting vs. standing position and lean body mass (P = 0.048), yet no associations between EE differences with the rest of the anthropometric and body composition parameters were observed in each position pair studied (all P>0.321). Our findings support the fact that increasing the time spent standing could be a simple strategy to slightly increase EE. Therefore, our results have important clinical implications including a better monitoring, characterizing, and promoting countermeasures to sedentariness through low-level physical activities. Show less
AimsTo examine the association between UCP1, UCP2, and UCP3 gene polymorphisms with adiposity markers in European adolescents and to test if there were gene interactions with objectively measured... Show moreAimsTo examine the association between UCP1, UCP2, and UCP3 gene polymorphisms with adiposity markers in European adolescents and to test if there were gene interactions with objectively measured physical activity and adiposity.MethodsA cross-sectional study that involves 1.057 European adolescents (12-18years old) from the Healthy Lifestyle in Europe by Nutrition in Adolescence Cross-Sectional Study. A total of 18 polymorphisms in UCP1, UCP2, and UCP3 genes were genotyped. We measured weight, height, waist, and hip circumferences and triceps and subscapular skinfold thickness. Physical activity was objectively measured by accelerometry during 7days.ResultsThe C allele of the UCP1 rs6536991 polymorphism was associated with a lower risk of overweight (odds ratio [OR]: T/C+C/C vs T/T)=0.72; 95% confidence interval [CI]: 0.53-0.98; P=0.034; false discovery rate [FDR]=0.048). There was a significant interaction between UCP1 rs2071415 polymorphism and physical activity with waist-to-hip ratio (P=0.006; FDR=0.026). Adolescents who did not meet the physical activity recommendations (less than 60min/day of moderate to vigorous physical activity) and carrying the C/C genotype had higher waist-to-hip ratio (+ 0.067; 95% CI, 0.028-0.106; P=0.003), while no differences across genotypes were observed in adolescents meeting the recommendations.ConclusionsTwo UCP1 polymorphisms were associated with adiposity in European adolescents. Meeting the daily physical activity recommendations may overcome the effect of the UCP1 rs2071415 polymorphism on obesity-related traits. Show less
Background & aim: The thermic effect of food (TEF) refers to the increase of the metabolic rate and body temperature in response to a single meal. To date, most of the studies have focused to... Show moreBackground & aim: The thermic effect of food (TEF) refers to the increase of the metabolic rate and body temperature in response to a single meal. To date, most of the studies have focused to determine the TEF in terms of energy expenditure, but little is known about which is the response in terms of skin temperature. The aim of this study was to analyze whether the thermic effect of food (TEF) on the skin temperature with a standardized and individualized liquid meal test is different in young adult men than in young adult women.Methods: A total of 104 young adults (36 men and 68 women, age: 18-25 years old) consumed a standardized and individualized liquid meal (energy intake: 50% of measured basal metabolic rate, 50% carbohydrates, 35% fat, 15% protein). The skin temperature was measured by means of 17 iButtons during 3 h and 20 min. The mean, proximal, distal, and supraclavicular skin temperature, as well as the peripheral gradient, were determined as a proxy of a peripheral vasoconstriction. The participants reported the thermal sensation of the whole body, clavicular, feet, and hands zones. The body composition was measured by dual X-ray absorptiometry.Results: The overall, mean, proximal, and supraclavicular skin temperature significantly increased after the meal intake (all P < 0.05 vs. the baseline temperature). There was a postprandial peripheral vasoconstriction right after the meal intake and over the first hour and a peripheral vasodilatation during the second and third hour. Women had a higher increase in all skin temperature parameters in comparison to men (all, P < 0.05), whereas there were no sex differences in the proximal skin temperature (P = 0.279). The pattern of thermal sensation was similar between sexes, but women always felt colder than men. All of the results persisted after adjusting the analyses for body composition or menstrual cycle.Conclusion: A standardized and individualized liquid meal test increases the skin temperature in young adults, being the thermic effect higher in women than in men. (C) 2018 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved. Show less
Dairy products are thought to improve recovery after both resistance and endurance exercises due to their nutritional proprieties. We systematically reviewed the effects of dairy product intake on... Show moreDairy products are thought to improve recovery after both resistance and endurance exercises due to their nutritional proprieties. We systematically reviewed the effects of dairy product intake on exercise performance and recovery of muscle function in humans. A literature search was conducted in the MEDLINE (via PubMed) and Web of Science databases from their inception to 15th April 2018. The initial search retrieved 7708 articles, and a total of 11 studies were finally included after applying inclusion and exclusion criteria. All the selected studies were conducted with cow's milk. Whereas some studies found significant positive effect of cow's milk on exercise performance and recovery of muscle function, others did not find any effect. These controversies could be due to the heterogeneity of cow's milk ingestion (e.g., amount of cow's milk, timing of consuming the cow's milk), to the type of intervention, and to the large heterogeneity of outcomes measured. Limited studies exist examining the effects of cow's milk consumption and its influence on exercise performance and recovery of muscle function, therefore further studies are needed to draw more definitive conclusions. Show less
Having valid and reliable resting energy expenditure (REE) estimations is crucial to establish reachable goals for dietary and exercise interventions. However, most of the REE predictive equations... Show moreHaving valid and reliable resting energy expenditure (REE) estimations is crucial to establish reachable goals for dietary and exercise interventions. However, most of the REE predictive equations were developed some time ago and, as the body composition of the current population has changed, it is highly relevant to assess the validity of REE predictive equations in contemporary young adults. In addition, little is known about the role of sex and weight status on the validity of these predictive equations. Therefore, this study aimed to investigate the role of sex and weight status in congruent validity of REE predictive equations in young adults. A total of 132 young healthy adults (67.4% women, 18-26 years old) participated in the study. We measured REE by indirect calorimetry strictly following the standard procedures, and we compared it to 45 predictive equations. The most accurate equations were the following: (i) the Schofield and the Food and Agriculture Organization of the United Nations/World Health Organization/United Nations (FAO/WHO/UNU) equations in normal weight men; (ii) the Mifflin and FAO/WHO/UNU equations in normal weight women; (iii) the Livingston and Korth equations in overweight men; (iv) the Johnstone and Frankenfield equations in overweight women; (v) the Owen and Bernstein equations in obese men; and (vi) the Owen equation in obese women. In conclusion, the results of this study show that the best equation to estimate REE depends on sex and weight status in young healthy adults. Show less
