7 Clinical Trials for Various Conditions
Brown adipose tissue becomes activated during cold conditions to increase thermogenesis (i.e., energy expenditure). Topical menthol application increases resting energy expenditure but it is unclear whether brown adipose tissue activation contributes to this rise in the energy expenditure. The overall goal with this project is to determine whether topical menthol application stimulates brown adipose tissue.
The regulation of human body weight and fatness is not fully understood. Although some models of regulation have been proposed (set point, dual-intervention point, others), no studies have been designed to test their predictions. In this pilot and feasibility study, the investigators will implement an experimental approach to test the predictions of models of body weight regulation in humans. Men and women with either low body weight or obesity will be exposed to a 2-day fasting followed by a 2-day ad-libitum refeeding. During the entire fasting-refeeding period, energy intake and expenditure will be accurately measured within metabolic chambers. The investigators will therefore determine the compensatory responses to fasting elicited to prevent weight loss. The results will serve to design and power future studies to better understand body weight regulation.
The purpose of this study is to test the hypothesis that a low-carbohydrate diet will impact hormones and other factors that regulate appetite and energy balance, and result in lower energy intake and greater weight loss, than a high complex carbohydrate diet.
With the alarming increase in the prevalence of obesity, identifying factors that predispose individuals to weight-gain is of critical importance. Even when caloric intake and physical activity levels are well controlled, susceptibility for weight-gain is heterogeneous. Basal metabolic rate (BMR) represents the largest portion of daily energy expenditure in normal adults, and as such, variability in BMR among individuals can be a major factor in determining the susceptibility for gaining weight. However, factors responsible for this variability in BMR and resistance to weight-gain remain unclear. Our preliminary data indicate that high-normal growth hormone (GH) concentration is associated with resistance to weight-gain in rats when overfed and greater weight-loss in humans when underfed. In addition, the investigators have found that the pulsatility of GH secretion has profound effects on several metabolic processes. Therefore, together these findings suggest that endogenous GH secretion is associated with body weight regulation, and the pulsatility (peak amplitude) of GH secretion, rather than the absolute GH concentration, per se, may be responsible for this effect. Because GH influences many of the key metabolic processes that contribute to BMR (e.g.; protein synthesis, proteolysis, substrate cycling), the investigators anticipate that the resistance to weight-gain in persons with elevated GH concentrations will be associated with an increase in BMR due to acceleration of some or all of these processes. Our overall hypothesis is that increased GH secretion can protect against weight-gain due to an augmentation of major metabolic processes that contribute to BMR. Identifying factors responsible for predisposing individuals to weight-gain will lead to establishing improved methods for reducing the prevalence of obesity.
The goal of this clinical trial is to test the effects of dietary composition on the rhythms of food intake, appetite regulation, and rhythms of energy expenditure. Participants will: complete 2 field-based dietary interventions be provided with standard meals record daily food intake in a real-time manner complete 2 inpatient stays be provided with standard meals have frequent blood draws provide urine, saliva, and stool samples
Background: Researchers want to learn how different diets affect hormone levels, body weight, energy expenditure, liver fat, and more. To do this, they will use specialized techniques and food plans. This is not a weight loss study. Objective: To better understand how low-fat and low-carbohydrate foods affect health. Eligibility: Men and women ages 18-50 who have a stable body weight and can exercise daily Design: Participants will have a screening visit that lasts 4-6 hours. It will include: Medical history Physical exam Fasting blood and urine tests Questionnaires Trying foods from the study Participants will be admitted to the Clinical Center and will stay for 4 weeks without leaving. They can have visitors. Participants will wear activity and glucose monitors throughout the study. They will be weighed daily and will complete daily exercise. They will eat 3 meals daily, plus snacks. They will give urine, saliva, and blood samples. They will fill out questionnaires and rate their hunger, appetite, and sense of taste. They will have body scans. For the scans, they will lie in a machine that takes X-ray pictures of the body. Participants will complete activities to measure how many calories they burn and how the diets affect them: Participants will drink special liquids to measure calories burned, sugar, and sense of taste. Participants will wear a plastic hood while resting. Participants will stay alone in a special room for 24 hours. Participants will eat a low-carb, high-fat diet for 2 weeks and a high-carb, low-fat diet for 2 weeks. Participants may be dismissed if they purposefully use the study to try to change their body weight. Sponsoring Institution: National Institute of Diabetes and Digestive and Kidney Diseases ...
Background: - Obesity is the result of many factors, including genetics and lifestyle, such as over-eating high-calorie foods and not being physically active. Obesity affects approximately one third of adults in the United States. Researchers often study individuals who are already overweight and obese, but another approach is to examine people who stay thin despite eating whatever they want and not exercising. Studying these thin individuals will enhance understanding of why some people become obese and others do not, which may lead to novel treatments for obesity. Objective: - To study the metabolism, body composition, body temperature, physical activity, and blood chemistries of healthy lean adults before and after adding 1,000 extra Calories per day to their normal diet. Eligibility: - Healthy adults, 30 to 50 years of age, who have never been overweight after adolescence, who are currently weight-stable, sedentary, and eating without restrictions. Design: - The entire study will take about 9 weeks and will include the following outpatient and inpatient visits: \<TAB\>- Outpatient screening visit and monitoring: Physical examination and blood test at screening; then, one week of physical activity monitoring (e.g., with a pedometer-like device called an accelerometer) and completing a food diary. \<TAB\>- Baseline inpatient visit (5 days): Volunteers will eat a normal diet to maintain body weight. Energy expenditure, body composition, physical fitness, activity level, and eating behavior will be measured. Urine and blood samples will be taken. Volunteers may go home for the weekend or stay at the metabolic clinical research unit (MCRU). \<TAB\>- Inpatient feeding week 1 (5 days): Volunteers will eat a normal diet plus milkshakes for added calories. All the same measurements during the baseline week visit will be repeated. \<TAB\>- Outpatient feeding weeks 2 3: Volunteers will eat breakfast at the MCRU everyday for the next 2 weeks and take prepared meals home with them (volunteers may also stay at the MCRU for the 2 weeks if they prefer). Volunteers will drink a non-radioactive (heavy) water called doubly labeled water to measure energy expenditure in their normal living environment Daily urine samples will be collected. \<TAB\>- Inpatient feeding week 4 (5 days): Volunteers will continue eating a normal diet plus milkshakes for added calories. This stay and measurement is identical to inpatient feeding week 1. - Volunteers will be contacted at 6 and 12 months to assess any changes in body weight, diet, and physical activity.