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

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

• Inclusion Criteria:

• Ages 19-35
• Men and women

Exclusion criteria

• 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 tuberculosis.
• 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 months.
• 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 randomization
• 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.