Predicting Adaptive Thermogenesis

Detailed Summary

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 activity level * 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 temperature * 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

Study Details

Timeline

Interventions