Influence of Ambient Temperature on Food Intake Through a Randomized Control Trial in an Office Setting

Food Intake in 2 Thermal Environments

food intake, indoor thermal environment

Based on preliminary data and previous studies, the investigators hypothesize that the ambient temperature experienced by an individual influences his or her food intake in males and females aged 19 to 30. Specifically, exposure to temperatures above the thermoneutral zone (TNZ) will decrease consumption in young adults in a sedentary situation. Researchers will execute a randomized control trial specifically testing thermal exposure and its effect on an individual's food consumption. Participants will receive and wear a t-shirt. They will have a thermal image taken of the inner canthus of their eye and middle finger nail bed, representing a baseline of core and peripheral temperatures, respectively. They will be randomized to either a colder environment (65°F) or a warmer environment (75°F) under the artifice of monitoring routine office work with abnormal temperature conditions. Their knowledge of the experiment will be limited until the end. They will experience this temperature while filling out paperwork and performing basic office tasks. After one hour, another thermal image will be taken. Each participant will be presented with a large, Mellow Mushroom cheese pizza and directed to eat at their leisure and subsequently finish the office tasks over the next hour. The participants will then be debriefed on the parameters of the experiment and body measurements will be taken at the end so as to prevent bias of the subject by limiting their food intake. The investigators will quantify energy intake by weighing remaining food and comparing to known caloric content by weight from bomb calorimetry tests. The infrared thermal images will determine whether the temperatures experienced were extreme enough to initiate a change in thermoregulation.

Previous studies suggest increased time spent outdoors is associated with lower body mass index (BMI).1,2 . In addition, energy expenditure and hunger have been associated with exposure to heat or cold. Increased usage of central heating and air conditioning systems coupled with increased time spent indoors has created an environment where humans are expending less energy to regulate their body temperature.3 The human thermoneutral zone (TNZ) is the range of ambient temperatures in which a healthy adult can maintain body temperature without expending energy beyond the normal basal metabolic rate. Energy intake and expenditure are adjusted at temperatures above and below the TNZ.4 The temperature of the food, smell, time of consumption, and number of people present are established factors that influence food consumption in humans.5 In addition, evidence supports the role of the environment upon an individual's food intake. Wall color, lighting, and ambient noise, influence consumption preferences and quantities.6 Based on research in animal models, particularly mice and livestock,food intake and subsequently, weight gain is reduced in high ambient temperatures.7-10 In addition in young, physically active, healthy males, food intake is inversely proportional to TNZ.11 However, energy expenditure increases above and below the TNZ. These studies are based on extreme conditions, therefore there is a lack of information on how small changes in ambient temperature may affect food intake in the general human public. Recent research shows the effectiveness of small changes over time to lead to changes in consumption practices.12 Thus, altering the thermal environment subtly may lead to a greater understanding of long term effects in weight management. The investigators have previously examined the thermal environment of persons going about their daily lives in both urban and rural settings (X120217008). Preliminary analysis of the results suggest increased % body fat is associated with lower heat exposure.

United States