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.
- Inclusion Criteria:
- Ages 19-35
- Men and women
- Exclusion Criteria:
- Any food allergy, including, but not limited to lactose or gluten intolerance.
- Religious affiliations that include specific food guidelines.
- Personal dietary restrictions, including but not limited to veganism.
- Participation in any weight-reduction program, weight-loss diet, or other
special diet within the previous 3 months.
- Weight loss or gain of >5% of body weight in the past 6 months for any reason
except post-partum weight loss.
- Currently taking medication that suppresses or stimulates appetite or that
affects body weight, including oral anti-diabetic medications.
- History of prior surgical procedure for weight control or liposuction.
- Anyone currently taking statins.
- Self report of high blood pressure (above 140 systolic, 90 diastolic)
- Current smoker or quit smoking less than 6 months prior.
- Any major disease, including:
- Active cancer or cancer requiring treatment in the past 2 years (except
nonmelanoma skin cancer).
- Active or chronic infections, including self-reported HIV positivity and
- Active cardiovascular disease or event including hospitalization or
therapeutic procedures for treatment of heart disease (e.g., coronary
artery bypass, percutaneous transluminal coronary angioplasty) in the past
6 months; New York Heart Association Functional Class >2 with respect to
congestive heart failure; stroke or transient ischemic attack in the past 6
- Gastrointestinal disease, including self-reported chronic hepatitis or
cirrhosis, any episode of alcoholic hepatitis or alcoholic pancreatitis
within past year, inflammatory bowel disease requiring treatment in the
past year, recent or significant abdominal surgery (e.g., gastrectomy).
- Active renal disease.
- Lung disease: chronic obstructive airway disease requiring use of oxygen.
- Diagnosed diabetes (type 1 or 2).
- Uncompensated or uncontrolled psychiatric disease (such as schizophrenia
and bipolar disorder) that, in opinion of the investigators, would impede
conduct of the trial or completion of procedures.
- Self reported history of or current eating disorders
- Conditions or behaviors likely to effect the conduct of the trial: unable or
unwilling to give informed consent; unable to communicate with the pertinent
staff; another household member is a participant or staff member in the trial;
current or anticipated participation in another research project that would
interfere with the offered session; unwilling to accept condition assignment by
- Currently taking antidepressant, steroid, or thyroid medication, unless dosage
has been stable for at least 6 months.
- Self-report of a recent or ongoing problem with drug abuse or addiction.
- Self report of excessive alcohol intake, either acute or chronic, defined as any
one of the following: 1) average consumption of 3 or more alcohol containing
beverages daily; 2) consumption of 7 or more alcoholic beverages within a 24-hr
period in the past 12 months
- Pregnancy and childbearing: currently pregnant or less than 3 months post
partum; currently nursing or within 6 weeks of having completed nursing;
pregnancy anticipated during between time of screening and session date;
unwilling to report possible or confirmed pregnancies promptly during the course
of the trial;
- Students in the Environmental Health Science Department, Nutrition Sciences
School, Any student, trainee, or post-doctoral fellow who is directly or
indirectly receiving funding from the Nutrition Obesity Research Center.
- Any other conditions which, in opinion of the investigators, would adversely
affect the conduct of the trial.