Dietary Modification, Exogenous Obesity
Conditions
Keywords
energy metabolism, lipids, lipoproteins, satiety, glycemic load, insulin
Brief summary
The purpose of this study is to determine if consumption of meals containing carbohydrates with different glycemic index (a high glycemic index meal and a low glycemic index meal)have different effects on energy expenditure, type of metabolic fuels used for energy, blood lipids and lipoproteins, and sensations of hunger, fullness, and the hormones related to satiety.
Detailed description
Little is known about the metabolic effects of chronic dieting and weight cycling in humans, but limited evidence suggests that fatty acid oxidation may be depressed leading to periodic elevation of circulating lipids associated with meal ingestion and preferential storage of fat in adipose tissue. With the traditional approach of restrictive dieting failing to result in permanent weight loss and, possibly producing abnormalities in lipid metabolism, it is important to evaluate alternative approaches to achieve a healthy body weight through improved metabolism. In this study the investigators will test the postprandial metabolic effects of standard mixed meals containing carbohydrates with high glycemic index and compare these effects to responses obtained with standard mixed meals, matched for protein and fat content but containing carbohydrates with low glycemic index.
Interventions
OTHERHigh Glycemic Index meals
Dietary intervention with meals containing high glycemic index carbohydrates. All foods provided to meet the individual's energy needs. Standardized test meal (breakfast)also contained only high glycemic index carbohydrates and energy content was adjusted for each individual, providing 40% of daily energy needs.
OTHERLow Glycemic Index meals
Dietary intervention with meals containing low glycemic index carbohydrates. All foods provided to meet the individual's energy needs. Standardized test meal (breakfast)also contained only low glycemic index carbohydrates and energy content was adjusted for each individual, providing 40% of daily energy needs.
Sponsors
USDA, Western Human Nutrition Research Center
Study design
Allocation
RANDOMIZED
Intervention model
CROSSOVER
Primary purpose
BASIC_SCIENCE
Masking
SINGLE (Outcomes Assessor)
Eligibility
Sex/Gender
FEMALE
Age
18 Years to 48 Years
Healthy volunteers
Yes
Inclusion criteria
* Body mass index between 25 and 30 kg/m2 * Having regular menses * Willing to refrain from restrictive dieting during the course of the study
Exclusion criteria
* Pregnant or currently planning a pregnancy * Cigarette smoking * Taking medications to induce weight loss or change appetite * History of cardiovascular disease * History of metabolic disorders, including diabetes
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Respiratory Gas Exchange | 30 minutes before a standardized test meal and intermittently for 480 minutes following the meal. | Respiratory Gas Exchange will be measured using an automated metabolic cart. Gas analyzers and volumeter will be calibrated using manufacturer's procedures. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Circulating lipoproteins | 4 blood samples taken over a 480 minute period | Blood samples for lipoprotein analyses were taken at fasting (0 minute) and at 150, 210, and 480 minutes following consumption of test meal. A subset of 10 randomly-selected subjects was chosen for this outcome measure |
| Subjective evaluation of appetite | 16 timepoints measured over 600 minutes | Visual analog scales were used to assess appetite-related sensations. Four responses were obtained during the fasting phase (120 minutes) and 12 responses were obtained in the 480 minute postprandial period. |
| Food consumption at a buffet-style meal | at 480 minutes following test meal | The amount and types of foods consumed were measured after subject was presented with a buffet-style meal. |
| Body composition | measured the morning of the standard meal challenge | Body composition (fat mass, % fat, lean mass, bone density) will be measured using dual energy x-ray absorptiometry. |
| Plasma glucose | 10 blood samples taken over a 480 minute period. | 1 fasting blood sample (0 minutes) and 9 post-prandial blood samples taken at 30, 60, 90, 120, 150, 210, 270, 360 and 480 minutes following consumption of standardized test meal. |
| Plasma leptin | 10 blood samples taken over a 480 minute period | 1 fasting blood sample (0 minutes) and 9 post-prandial blood samples taken at 30, 60, 90, 120, 150, 210, 270, 360 and 480 minutes following consumption of test meal. |
| Plasma ghrelin | 10 blood samples taken over a 480 minute time period | 1 fasting blood sample (0 minutes) and 9 post-prandial blood samples taken at 30, 60, 90, 120, 150, 210, 270, 360 and 480 minutes following consumption of test meal. |
| Cholecystokinin (CCK) | 10 blood samples taken over a 480 minute time period | 1 fasting blood sample (0 minutes) and 9 post-prandial blood samples taken at 30, 60, 90, 120, 150, 210, 270, 360 and 480 minutes following consumption of test meal. |
| GLP-1 | 10 blood samples taken over a 480 minute time period | 1 fasting blood sample (0 minutes) and 9 post-prandial blood samples taken at 30, 60, 90, 120, 150, 210, 270, 360 and 480 minutes following consumption of test meal. |
| Serum insulin | 10 blood samples taken over a 480 minute time period | 1 fasting blood sample (0 minutes) and 9 post-prandial blood samples taken at 30, 60, 90, 120, 150, 210, 270, 360 and 480 minutes following consumption of test meal. |
Countries
United States
Outcome results
None listed