RESUMO
BACKGROUND: Mild cold exposure increases energy expenditure and can influence energy balance, but at the same time it does not increase appetite and energy intake. OBJECTIVE: To quantify dermal insulative cold response, we assessed thermal comfort and skin temperatures changes by infrared thermography. METHODS: We exposed healthy volunteers to either a single episode of environmental mild cold or thermoneutrality. We measured hunger sensation and actual free food intake. After a thermoneutral overnight stay, five males and five females were exposed to either 18°C (mild cold) or 24°C (thermoneutrality) for 2.5 h. Metabolic rate, vital signs, skin temperature, blood biochemistry, cold and hunger scores were measured at baseline and for every 30 min during the temperature intervention. This was followed by an ad libitum meal to obtain the actual desired energy intake after cold exposure. RESULTS: We could replicate the cold-induced increase in REE. But no differences were detected in hunger, food intake, or satiety after mild cold exposure compared with thermoneutrality. After long-term cold exposure, high cold sensation scores were reported, which were negatively correlated with thermogenesis. Skin temperature in the sternal area was tightly correlated with the increase in energy expenditure. CONCLUSIONS: It is concluded that short-term mild cold exposure increases energy expenditure without changes in food intake. Mild cold exposure resulted in significant thermal discomfort, which was negatively correlated with the increase in energy expenditure. Moreover, there is a great between-subject variability in cold response. These data provide further insights on cold exposure as an anti-obesity measure.
RESUMO
BACKGROUND/OBJECTIVES: The objective of this study was to develop approaches to expressing resting energy expenditure (REE) and lean body mass (LM) phenotypes of metabolic disorders in terms of Z-scores relative to their predicted healthy values. SUBJECTS/METHODS: Body composition and REE were measured in 135 healthy participants. Prediction equations for LM and REE were obtained from linear regression and the range of normality by the standard deviation of residuals. Application is demonstrated in patients from three metabolic disorder groups (lipodystrophy, n=7; thyrotoxicosis, n=16; and resistance to thyroid hormone (RTH), n=46) in which altered REE and/or LM were characterised by departure from the predicted healthy values, expressed as a Z-score. RESULTS: REE (kJ/min) = -0.010 × age (years)+0.016 × FM (kg)+0.054 × fat-free mass (kg)+1.736 (R2 = 0.732, RSD = 0.36 kJ/min). LM (kg)=5.30 × bone mineral content (kg)+10.66 × height2 (m)+6.40 (male). LM (kg)=0.20 × fat (kg)+14.08 × height2 (m)-2.93 (female).(male R2=0.55, RSD = 3.90 kg; female R2 = 0.59, RSD=3.85 kg).We found average Z-scores for REE and LM of 1.77 kJ/min and -0.17 kg in the RTH group, 5.82 kJ/min and -1.23 kg in the thyrotoxic group and 2.97 kJ/min and 4.20 kg in the LD group. CONCLUSION: This approach enables comparison of data from individuals with metabolic disorders with those of healthy individuals, describing their departure from the healthy mean by a Z-score.
