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.
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.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
SINGLE
Enrollment
28
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.
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.
Western Human Nutrition Research Center
Davis, California, United States
Respiratory Gas Exchange
Respiratory Gas Exchange will be measured using an automated metabolic cart. Gas analyzers and volumeter will be calibrated using manufacturer's procedures.
Time frame: 30 minutes before a standardized test meal and intermittently for 480 minutes following the meal.
Plasma glucose
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.
Time frame: 10 blood samples taken over a 480 minute period.
Circulating lipoproteins
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
Time frame: 4 blood samples taken over a 480 minute period
Subjective evaluation of appetite
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.
Time frame: 16 timepoints measured over 600 minutes
Food consumption at a buffet-style meal
The amount and types of foods consumed were measured after subject was presented with a buffet-style meal.
Time frame: at 480 minutes following test meal
Body composition
Body composition (fat mass, % fat, lean mass, bone density) will be measured using dual energy x-ray absorptiometry.
Time frame: measured the morning of the standard meal challenge
This platform is for informational purposes only and does not constitute medical advice. Always consult a qualified healthcare professional.
Serum insulin
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.
Time frame: 10 blood samples taken over a 480 minute time period
Plasma leptin
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.
Time frame: 10 blood samples taken over a 480 minute period
Plasma ghrelin
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.
Time frame: 10 blood samples taken over a 480 minute time period
Cholecystokinin (CCK)
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.
Time frame: 10 blood samples taken over a 480 minute time period
GLP-1
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.
Time frame: 10 blood samples taken over a 480 minute time period