Physical and Behavioral Traits of Overweight and Obese Adults

Although complex metabolic, hormonal, and neural networks operate to control body weight, obesity is in most cases, the result of over-feeding and inactivity. In most obese patients, patterns of fundamental behavior determine the success or failure of weight loss interventions. Behavior is controlled to some degree by conscious decision making and is influenced by signals from the integrated networks involved in body weight regulation. The contributions of behavior, environment, socioeconomic status, physiology and genetics assure that no single therapeutic regimen will be successful in all obese individuals. In order to explore the factors that impede weight loss and result in weight regain, the obese phenotype and its variants must be defined. The purpose of this study is to detail hormonal, metabolic, cognitive and behavioral traits across the spectrum of weight categories utilizing the state-of the-art facilities of the Metabolic Units at the Mark O. Hatfield Clinical Research Center, NIH. Genetic material will be banked for analysis of phenotypic subgroups as they emerge.

Patients over the age of 18 are eligible for this study. While childhood obesity is an important public health issue, the variables of growth and hormonal controls will be delineated in separate studies. Over-weight and obese patients are encouraged to participate in as full an evaluation as feasible. Lean individuals will be recruited to create a normative database for body composition (dual energy x-ray absortiometry, air displacement plethysmography), energy expenditure (resting energy expenditure, 24h respiratory chamber and doubly labeled water) and other techniques used to study traits of importance. The study will be conducted in both the inpatient and outpatient setting and can include evaluation of hormones, diurnal variation, sleep, eating behavior and taste perception, physical fitness, psychological and neurocognitive functioning. Importantly, this protocol is the means by which pilot data are obtained to develop novel approaches and hypotheses for studying obesity and its associated traits.

• INCLUSION CRITERIA:

Obese subjects:

• Obese men and women over the age of 18 years
• BMI > 30

Overweight subjects:

• Overweight men and women over the age of 18 years
• BMI > 25 and < 30

Control subjects (may be matched for age, sex and years of education):

• Normal weight men and women over the age of 18 years
• BMI > 18.5 and < 25

Exclusion criteria

• Patients with significant physical limitations that may preclude them from completing the majority of the tests in this study
• Current unstable medical conditions including cardiac ischemia, severe respiratory insufficiency requiring oxygen therapy, hepatic or cardiac failure as assessed by history and physical exam
• Any psychiatric condition that would preclude participation in the study
• Patients unwilling or unable to give informed consent
• Pregnant woman.

Additional exclusion for lean control subjects:

• Previous history of obesity as an adolescent or adult
• Current or past history of eating disorders such as anorexia nervosa or bulimia

The NIH Patient Recruitment and Public Liaison Office will receive inquiries from interested study subjects. Pre-screening by this office will exclude patients who require more than minimal assistance to complete activities of daily living in order to select subjects who can safely participate in the full phenotyping protocol. All others will be contacted by the protocol team to review exclusion criteria. Eligible patients will be invited to Clinical Research Center for a screening visit.