Influence of Ambient Temperature on Food Intake Through a Randomized Control Trial in an Office Setting
Condition: Food Intake in 2 Thermal Environments
Study type: Interventional

Summary: 
      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.
    

Detailed description: 
      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.
    

Intervention name(s): Thermal Environment
Intervention type(s): Other
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Single (Participant)
Primary purpose: Health Services Research
Keywords: food intake; indoor thermal environment