Article

Association of Ambient Indoor Temperature with Body Mass Index in England

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Abstract

Objective: Raised ambient temperatures may result in a negative energy balance characterized by decreased food intake and raised energy expenditure. This study tested whether indoor temperatures above the thermoneutral zone for clothed humans (∼23 °C) were associated with a reduced body mass index (BMI). Methods: Participants were 100,152 adults (≥16 years) drawn from 13 consecutive annual waves of the nationally representative Health Survey for England (1995-2007). Results: BMI levels of those residing in air temperatures above 23 °C were lower than those living in an ambient temperature of under 19 °C (b = -0.233, SE = 0.053, P < 0.001), in analyses that adjusted for participant age, gender, social class, health and the month/year of assessment. Robustness tests showed that high indoor temperatures were associated with reduced BMI levels in winter and non-winter months and early (1995-2000) and later (2001-2007) survey waves. Including additional demographic, environmental, and health behavior variables did not diminish the link between high indoor temperatures and reduced BMI. Conclusions: Elevated ambient indoor temperatures are associated with low BMI levels. Further research is needed to establish the potential causal nature of this relationship.

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... One factor that is generally considered of negligible importance in the energy budgets of humans is the cost of thermoregulation. This is because it is assumed that humans spend most of their lives at thermoneutral temperatures 4 where there are no thermoregulatory demands. Yet there is some indirect evidence suggesting that humans do expend energy on thermoregulation. ...
... If these changes have physiological consequences that are not compensated by elevated food intake, then we would predict that the prevalence of obesity, and type 2 diabetes, should be reduced in areas where it is colder. Several previous studies have noted correlations between obesity prevalence and ambient temperatures, or a role Scientific RepoRts | 6:30409 | DOI: 10.1038/srep30409 for ambient temperature in individual susceptibility to obesity 4,21,22 , but the results are confused. Some studies have suggested obesity (BMI) is increased at higher temperatures 4 , others have suggested it is decreased 21 , while yet others find no significant effect 22 . ...
... This could for example be because any elevation in energy expenditure is offset by a compensatory increase in appetite and food intake 3 . These data are consistent with a previous study of impacts of ambient temperature on obesity prevalence 22 but contrast other studies where effects have been observed 4,21 . These latter observations may be because of inadequate control for confounding factors or using different measures of temperature. ...
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Cold exposure stimulates energy expenditure and glucose disposal. If these factors play a significant role in whole body energy balance, and glucose homeostasis, it is predicted that both obesity and type 2 diabetes prevalence would be lower where it is colder. Previous studies have noted connections between ambient temperature and obesity, but the direction of the effect is confused. No previous studies have explored the link of type 2 diabetes to ambient temperature. We used county level data for obesity and diabetes prevalence across the mainland USA and matched this to county level ambient temperature data. Average ambient temperature explained 5.7% of the spatial variation in obesity and 29.6% of the spatial variation in type 2 diabetes prevalence. Correcting the type 2 diabetes data for the effect of obesity reduced the explained variation to 26.8%. Even when correcting for obesity, poverty and race, ambient temperature explained 12.4% of the variation in the prevalence of type 2 diabetes, and this significant effect remained when latitude was entered into the model as a predictor. When obesity prevalence was corrected for poverty and race the significant effect of temperature disappeared. Enhancing energy expenditure by cold exposure will likely not impact obesity significantly, but may be useful to combat type 2 diabetes.
... However, with a decrease in ambient temperature below the thermoneutral zone, an extra energy expenditure of 105 to 156 kJ/day/1°C is needed to maintain thermal homeostasis [11]. Previously, only a few studies have suggested a possible association between outdoor or indoor temperature and obesity [12][13][14][15][16], and most of the studies are from Western populations. ...
... In this study, a maximum prevalence for obesity was observed in counties with average temperatures near 18°C, while the extremes of temperature category tended to the lowest odds for obesity. In another study, BMI levels of those residing in indoor temperatures above 23°C were lower than those living in temperatures below 19°C, suggesting an inverse correlation between BMI and ambient temperature using data from a nationally representative health survey administered in England [15]. In addition to these cross-sectional studies, one longitudinal observation study was conducted among Dutch children. ...
... The discrepancy surrounding ambient temperature and obesity might be a consequence of the different ranges in mean temperatures, different altitudes of observed areas, different ethnic groups, and the heterogeneous adjustment for confounding variables in previous studies. However, although some reports do not include a significant number of locations with extreme ambient temperatures [13,15], they generally support the concept of parabolic association between ambient temperature and obesity [14], with the highest prevalence of obesity around 18-20°C. In our study, the range of mean annual ambient temperatures was between 6.6°C and 16.6°C, and therefore, extremely high or low temperatures were not included. ...
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... Obese people are under higher heat strain than lean people, and are under increased risk of heat-related disorders (e.g., heatstroke, heat cramps, and heat exhaus on) (Bar-Or et al., 1969;Buskirk E. R. et al., 2006;Chung and Pin, 1996). Some surveys have suggested that people with higher BMI tend to prefer lower temperatures (Daly, 2014;Rupp et al., 2018). In the tropics, this would imply higher cooling energy needs for people with higher BMI, we may speculate that this may also a ect the issue of building overcooling. ...
... However, assuming neutral thermal sensa on as preferred temperature could be misleading. Results of our study, in laboratory condi ons, con rmed conclusions of eld surveys that occupants with higher BMI values tend to prefer lower temperature set-points (Daly, 2014;Rupp et al., 2018). Taking into account the increasing prevalence of overweight and obesity in the popula on, it could limit energy-saving strategies for tropical climates (Duarte et al., 2017;Lipczynska et al., 2018), while in temperate and cold climates support energy-e cient controls. ...
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Globally 39% of adults are overweight, 13% are obese, and 9% are underweight. Current thermal comfort standards, catering to the normal weight occupant, may hence be ignoring nearly 60% of the population. This could have significant comfort, productivity and energy implications. We performed a climate chamber study of the thermal response of 76 subjects in all the body mass index (BMI) categories, from 17 and 37 kg/m2. Every participant underwent the same four sessions at average operative temperatures of 19.9, 22.4, 25.3, and 28.2 °C. We obtained subjective feedback from participants on their thermal sensation and preference, humidity sensation and preference, thermal comfort rating, and air quality perception. We also measured skin temperature, blood pressure, pulse rate, blood glucose level, weight, height, waist and hip circumferences and body composition. Overall, we did not find significant impact of BMI on the thermal sensation. However, the overweight and obese participants preferred lower temperature compared to normal weight and underweight participants which may indicate practical implication for control strategies.
... Evidence in humans is limited by extreme temperatures or physical activity, limited ambient temperature ranges, or lack of randomization (7,8); thus, our ability to draw conclusions is limited. While there has been some exploration of the effects of cold exposures (9)(10)(11)(12) and exploration into adaptive thermal comfort and building standards (13)(14)(15)(16)(17), to what extent small increases above the thermoneutral zone may influence caloric consumption is largely unexplored. ...
... This temperature range is the "thermoneutral zone" for clothed humans [105]. Individuals living at thermoneutral circumstances are more prone to obesity, whereas higher ambient temperatures (> 23°C) are associated with lower body mass index [45]. A study in mice [205] showed that animals living in a chronic thermoneutral environment (30°C) developed atherosclerosis based on metabolic inflammation of adipose tissue whereas the control group exposed to mild temperature stress (22°C) did not. ...
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Chronic non-communicable diseases (CNCD) are the leading cause of mortality in developed countries. They ensue from the sum of modern anthropogenic risk factors, including high calorie nutrition, malnutrition, sedentary lifestyle, social stress, environmental toxins, politics and economic factors. Many of these factors are beyond the span of control of individuals, suggesting that CNCD are inevitable. However, various studies, ours included, show that the use of intermittent challenges with hormetic effects improve subjective and objective wellbeing of individuals with CNCD, while having favourable effects on immunological, metabolic and behavioural indices. Intermittent cold, heat, fasting and hypoxia, together with phytochemicals in multiple food products, have widespread influence on many pathways related with overall health. Until recently, most of the employed challenges with hormetic effects belonged to the usual transient live experiences of our ancestors. Our hypothesis; we conclude that, whereas the total inflammatory load of multi-metabolic and psychological risk factors causes low grade inflammation and aging, the use of intermittent challenges, united in a 7–10 days lasting hormetic intervention, might serve as a vaccine against the deleterious effects of chronic low grade inflammation and it's metabolic and (premature) aging consequences.
... Cross-sectional, population-based surveys in Spain and England have shown discordant results regarding an association between ambient temperature and body mass index. Whereas British people residing in air temperatures above 23°C had a lower body mass index (BMI) than those living in an ambient indoor temperature of under 19°C, Spanish residents of various geographical locations were found to have increasing BMIs with increasing mean annual temperatures between 10.4 and 21.3°C [36,37]. ...
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Global warming, primarily caused by emissions of too much carbon dioxide, and climate change is a reality. This will lead to more extreme weather events with heatwaves and flooding. Some studies propose an association between thermal exposures and the prevalence of obesity with an increasing trend towards time spent in the thermal comfort zone. Longterm exposure to the thermal comfort zone can lead to a reduction of brown adipose tissue activity with an impact on energy expenditure and thermogenesis. Reduced seasonal cold exposure in combination with reduced diet-induced thermogenesis by a highly palatable high-fat and high-sugar diet and reduced physical activity contribute to the prevalence of obesity and the metabolic syndrome.
... Previous studies suggest increased time spent outdoors is associated with lower body mass index (BMI) (1,2). Increased usage of central heating and air conditioning systems coupled with increased time spent indoors has created an environment where humans are presumably expending less energy to regulate their body temperature (3). ...
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We wanted to examine if spontaneous physical activity contributes to non-shivering thermogenesis. Ten lean, healthy male subjects wore a physical activity, micro-measurement system whilst the room temperature was randomly altered at two hourly intervals between thermoneutral (72°F), cool (62°F) and warm (82°F) temperatures. Physical activity measured during the thermoneutral, cooling and warming periods was not significantly different. Cooling, increased EE above basal and thermoneutral values 2061 ± 344 kcal/day (p <0.01). Thus, the increase in energy expenditure associated with short-term environmental cooling in lean, healthy males does not appear to be due to increased spontaneous physical activity or fidgeting.
Article
The incidence of the metabolic syndrome has reached epidemic levels in the Western world. With respect to the energy balance, most attention has been given to reducing energy (food) intake. Increasing energy expenditure is an important alternative strategy. Facultative thermogenesis, which is the increase in energy expenditure in response to cold or diet, may be an effective way to affect the energy balance. The recent identification of functional brown adipose tissue (BAT) in adult humans promoted a renewed interest in nonshivering thermogenesis (NST). The purpose of this review is to highlight the recent insight in NST, general aspects of its regulation, the major tissues involved, and its metabolic consequences. Sustainable NST in adult humans amounts to 15% of the average daily energy expenditure. Calculations based on the limited available literature show that BAT thermogenesis can amount to 5% of the basal metabolic rate. It is likely that at least a substantial part of NST can be attributed to BAT, but it is possible that other tissues contribute to NST. Several studies on mitochondrial uncoupling indicate that skeletal muscle is another potential contributor to facultative thermogenesis in humans. The general and synergistic role of the sympathetic nervous system and the thyroid axis in relation to NST is discussed. Finally, perspectives on BAT and skeletal muscle NST are given.
Article
Domestic winter indoor temperatures in the USA, UK and other developed countries appear to be following an upwards trend. This review examines evidence of a causal link between thermal exposures and increases in obesity prevalence, focusing on acute and longer-term biological effects of time spent in thermal comfort compared with mild cold. Reduced exposure to seasonal cold may have a dual effect on energy expenditure, both minimizing the need for physiological thermogenesis and reducing thermogenic capacity. Experimental studies show a graded association between acute mild cold and human energy expenditure over the range of temperatures relevant to indoor heating trends. Meanwhile, recent studies of the role of brown adipose tissue (BAT) in human thermogenesis suggest that increased time spent in conditions of thermal comfort can lead to a loss of BAT and reduced thermogenic capacity. Pathways linking cold exposure and adiposity have not been directly tested in humans. Research in naturalistic and experimental settings is needed to establish effects of changes in thermal exposures on weight, which may raise possibilities for novel public health strategies to address obesity.
Article
During the last four decades the world has experienced an epidemic of overweight individuals in affluent as well as developing countries. The WHO has predicted a "globesity epidemic" with more than 1 billion adults being overweight and at least 300 million of these being clinically obese. Obesity among children and adolescents is of great significance. From a global population perspective, this epidemic in weight gain and its sequelae are the largest public health problems identified to date and have very significant adverse implications for population health, and have by now almost reached the proportion of a pandemic. While genetic changes have been discussed as a cause of the epidemic, there has been too little time since its start to enable enough genetic adaptation to take place for this to provide a valid explanation. Traditionally positive energy balance and sedentary life style have been regarded as the primary causal factors; however, these factors have so far failed to provide explanations for the entire problem. For these reasons it seems warranted to investigate other possible co-factors contributing to the "globesity epidemic" and to find efficient strategies to counteract further increases in the size and nature of the epidemic. The purpose of this paper is to discuss a potential preventive co-factor, thermogenesis. Special attention has been paid to the influence of ambient temperature as a grossly neglected factor in the debate. As most people today live and work at ambient temperatures close to their body temperature (the thermal neutral point), we hypothesise that this is an important causal co-factor in the "globesity" epidemic. The hypothesis: The null hypothesis that adaptive thermogenesis in brown adipose tissue in adult humans is not significant for weight loss is rejected. We propose the hypothesis that homoeothermic living conditions close to the thermogenic neutral level is an important causal co-factor in the "Globesity" Epidemic.
Article
Summary When exposed for 18 hours to temperatures between 65 and 76°F., adult male rats increased their food intake, gained weight normally, and avoided hypothermia. At temperatures above 92°F., food intake was low, water intake was somewhat increased, and the rats lost weight rapidly and experienced fever. These data indicate that food intake is not necessarily determined by total energy expenditure, nor by the animal's body temperature. Rather, food intake appears to be controlled as if it is a mechanism of temperature regulation. The amount of food eaten appears to be determined, at least partly, by the organism's ability to dissipate the heat of food metabolism (Rubner's "Specific dynamic action").
Article
Ambient temperature has been shown to affect energy metabolism in field situations. Therefore, we assessed the effect of a short exposure to the thermoneutral zone, i.e., 27 degrees C (81 degrees F), in comparison to the usual ambient temperature of 22 degrees C (72 degrees F), on energy expenditure (EE), substrate oxidation, and energy intake (EI) in a controlled situation. Subjects, i.e., women (ages 22+/-2 years, BMI 22+/-3, 28+/-4% body fat), stayed in a respiration chamber three times for 48 h each: once at 22 degrees C, and twice at 27 degrees C in random order, wearing standardized clothing, executing a standardized daily-activities protocol, and being fed in energy balance (EB). During the last 24 h at 22 degrees C, and once during the last 24 h at 27 degrees C, they were fed ad libitum. At 27 degrees C, compared to at 22 degrees C, EE was 8.9+/-1.3 MJ/day vs. 9.9+/-1.5 MJ/day (P<.001) due to decreases in diet-induced thermogenesis (DIT) and activity-induced energy expenditure (AEE) (P<.01); respiratory quotient (RQ) had increased (P<.05); core (P<.05) and skin (P<.001) temperatures had increased. During ad lib feeding, EI was 90-91% of EE (P=.9), due to changes in energy density (ED) of the food choice (P<.01), and related to changes in body temperature and EE (P<.001). Thus, at 27 degrees C, compared to 22 degrees C, energy metabolism was reduced by reductions in DIT and in AEE, while RQ was increased. Reduction in EI was primarily related to body temperature changes and secondarily to changes in EE.
Article
We studied interindividual variation in body temperature and energy expenditure, the relation between these two, and the effect of mild decrease in environmental temperature (16 vs. 22 degrees C) on both body temperature and energy expenditure. Nine males stayed three times for 60 h (2000-0800) in a respiration chamber, once at 22 degrees C and twice at 16 degrees C, in random order. Twenty-four-hour energy expenditure, thermic effect of food, sleeping metabolic rate, activity-induced energy expenditure, and rectal and skin temperatures were measured. A rank correlation test with data of 6 test days showed significant interindividual variation in both rectal and skin temperatures and energy expenditures adjusted for body composition. Short-term exposure of the subjects to 16 degrees C caused a significant decrease in body temperature (both skin and core), an increase in temperature gradients, and an increase in energy expenditure. The change in body temperature gradients was negatively related to changes in energy expenditure. This shows that interindividual differences exist with respect to the relative contribution of metabolic and insulative adaptations to cold.
Article
Objective: Assessment of the effect of a lowered ambient temperature, ie 16 degrees C (61 degrees F), compared to 22 degrees C (72 degrees F), on energy intake (EI), energy expenditure (EE) and respiratory quotient (RQ) in men. Design: Randomized within-subject design in which subjects stayed in a respiration chamber three times for 60 h each, once at 22 degrees C, and twice at 16 degrees C, wearing standardized clothing, executing a standardized daily activities protocol, and were fed in energy balance (EBI): no significant difference between EE and EI over 24 h). During the last 24 h at 22 degrees C, and once during the last 24 h at 16 degrees C, they were fed ad libitum. Subjects: Nine dietary unrestrained male subjects (ages 24+/-5 y, body mass index (BMI) 22.7+/-2.1 kg/m(2), body weight 76.2+/-9.4 kg, height 1.83+/-0.06 m, 18+/-5% body fat). Results: At 16 degrees C (EB), EE (total 24 h EE) was increased to 12.9+/-2.0 MJ/day as compared to 12.2+/-2.2 MJ/day at 22 degrees C (P<0.01). The increase was due to increases in sleeping metabolic rate (SMR; the lowest EE during three consecutive hours with hardly any movements as indicated by radar): 7.6+/-0.7 vs 7.2+/-0.7 MJ/day (P<0.05) and diet-induced thermogenesis (DIT; EE-SMR, when activity induced energy expenditure as indicated by radar=0): 1.7+/-0.4 vs 1.0+/-0.4 MJ/day (P<0.01). Physical activity level (PAL; EE/SMR) was 1.63-1.68. At 16 degrees C compared to at 22 degrees C, rectal, proximal and distal skin temperatures had decreased (P<0.01). RQ was not different between the two ambient temperature situations. During ad libitum feeding, subjects overate by 32+/-12% (at 22 degrees C) and by 34+/-14% (at 16 degrees C). Under these circumstances, the decrease of rectal temperature at 16 degrees C was attenuated, and inversely related to percentage overeating (r(2)=0.7; P<0.01). Conclusion: We conclude that at 16 degrees C, compared to 22 degrees C, energy metabolism was increased, due to increases in SMR and DIT. Overeating under ad libitum circumstances at 16 degrees C attenuated the decrease in rectal core body temperature.
Article
To compare overweight and lean subjects with respect to thermogenesis and physiological insulation in response to mild cold and rewarming. Ten overweight men (mean BMI, 29.2 +/- 2.8 kg/m(2)) and 10 lean men (mean BMI, 21.1 +/- 2.0 kg/m(2)) were exposed to cold air for 1 hour, followed by 1 hour of rewarming. Body composition was determined by hydrodensitometry and deuterium dilution. Heat production and body temperatures were measured continuously by indirect calorimetry and thermistors, respectively. Muscle activity was recorded using electromyography. In both groups, heat production increased significantly during cooling (lean, p = 0.004; overweight, p = 0.006). The increase was larger in the lean group compared with the overweight group (p = 0.04). During rewarming, heat production returned to baseline in the overweight group and stayed higher compared with baseline in the lean group (p = 0.003). The difference in heat production between rewarming and baseline was larger in the lean (p = 0.01) than in the overweight subjects. Weighted body temperature of both groups decreased during cold exposure (lean, p = 0.002; overweight, p < 0.001) and did not return to baseline during rewarming. Overweight subjects showed a blunted mild cold-induced thermogenesis. The insulative cold response was not different among the groups. The energy-efficient response of the overweight subjects can have consequences for energy balance in the long term. The results support the concept of a dynamic heat regulation model instead of temperature regulation around a fixed set point.
Methodology and documentation UK: Stationary Office
  • K Sproston
  • Primatesta
Sproston K, Primatesta P, eds. Health Survey for England 2003. Volume 3: Methodology and documentation. London, UK: Stationary Office; 2004.
Effects of heat on appetite
  • C P Herman
Herman CP. Effects of heat on appetite. In: Marriott BM, editor. Nutritional Needs in Hot Environments: Applications for Military Personnel in Field Operations. Washington DC: National Academy Press; 1993. p. 187-214.
Nutritional Needs in Hot Environments: Applications for Military Personnel in Field Operations
  • Herman CP