- Researchers who study health and nutrition are interested in developing more accurate
methods of determining what people eat from day to day and how it affects their general
health. In particular, better methods are needed to determine if people are accurately
remembering what they ate. One possible method involves the use of biomarkers, or indicators
in urine, blood, saliva, fat, and hair, which are related to the intake of a particular food
in a consistent way. One set of biomarkers in blood samples and hair may be used to determine
the relative amount of meat, fish, and soda (corn/sugar cane) in a person s diet. However,
more research is needed to study the effectiveness of using these biomarkers to accurately
track dietary intake.
- To validate the use of biomarkers as representative of specific dietary intake patterns
- Healthy, nondiabetic men between 18 and 65 years of age.
- This study involves an initial screening visit and a 12-13 week inpatient dietary study
- Participants will be screened with a medical history and physical examination, as well
as blood and urine samples and a glucose tolerance test to exclude individuals who have
- After 3 days of a standard weight-maintaining diet, participants will have a glucose
tolerance test and a body fat scan; provide hair, blood, and fat tissue samples; and
complete questionnaires and performance tests.
- Participants will spend one day in a metabolic chamber to measure their energy
expenditure and general metabolism.
- Participants will then be randomized into one of eight carefully designed diets for 12
weeks. The diets will differ in the amount of meat, fish, and soda, including one diet
where none of the three biomarker-related foods will be permitted. Blood samples will be
collected throughout the study diet period.
- At the end of the 12-week study diet period, participants will provide additional hair,
blood, and fat tissue samples, and will have a second metabolism assessment in the
This study will investigate how to better predict why some individuals gain or lose weight
more easily than others. It will examine whether the increase in the amount of energy a body
burns in 24 hours with overeating or the decrease over 24 hours with fasting can help
determine how easily someone gains or loses weight.
Healthy people between 18 and 60 years of age who have a body mass index (BMI) between 18.5
kg/m(2) and 24 kg/m(2) (for overfeeding study) or a BMI greater than 27 kg/m(2) with a body
weight less than 350 pounds (weight loss study) may be eligible for this study. The study
requires a 10-week admission to the NIH Clinical Center (2-week baseline, 6-week
overfeeding/weight loss, 2-week post-weight change).
Participants undergo the following tests and procedures during the hospital admission:
- Medical history, physical examination and laboratory studies
- Questionnaires to assess eating behavior, food preferences, body composition, and
- Body composition assessment (height, weight, waist circumference, and fat mass and
muscle content through DXA and MRI scans)
- Oral glucose tolerance test
- Meal test to measure the response of certain hormones to food
- Activity monitors to determine activity level
- Metabolic chamber study to measure calories burned over 24 hours and monitor body
- Free-living energy use study to measure calories burned under normal home conditions
over 7 days
- Fat and muscle biopsies
- Dietary intervention: Measurements of food intake and energy loss over a 6-week
overfeeding (1.5 times the subject s normal food intake) or weight loss (one-half the
subject s normal food intake) program
Followup procedures after the inpatient stay:
- Height and weight measurements at 6 months (overfeeding study participants) and monthly
for the first year, at 3-month intervals for the second year, and then yearly for 3 more
years (weight loss study participants)
- Yearly visits (2-night inpatient stay) for all participants for repeat meal test, DXA,
oral glucose tolerance test, behavioral questionnaires and, in women who can become
pregnant, pregnancy test
The prevalence of obesity in the United States has reached alarming proportions with 33% of
adults over the age of 20 being overweight. Obesity is more than twice as prevalent, however,
in the Pima Indians of Arizona. Although there have been a number of advances in our
understanding of the genetics of obesity, the environmental influences on the genetic
expression of obesity requires further investigation.
In an effort to understand some of the influences on the high prevalence of obesity in the
Pima Indians, the present study was designed to investigate eating behaviors and food
preferences, most especially the preference for high fat foods, in sib-pairs of Pima Indians
who have been previously genotyped in our genomic scan for loci linked to diabetes/obesity.
Most specifically, we will utilize several questionnaires and methods of assessing eating
behavior and the preference for high fat foods to create a food intake phenotype. In
addition, we will study Caucasians so that comparisons can be made between these two groups.
We will make these evaluations by assessing eating behavior, food preferences including usual
fat intake and preferences for high fat foods, body image perceptions, and energy
expenditure. It is hoped that the data gathered from this study will elucidate some of the
risk factors for the development of obesity among the Pima Indians.