This study is being conducted to learn more about the role of diet and exercise in regulating plasma triglyceride (fat) metabolism. The investigators will examine the effect of acute (24 hour) changes in energy intake and expenditure on fat metabolism the following day.
Excess body fat and a sedentary lifestyle are associated with increased plasma triglyceride (TG) and apolipoprotein B-100 (apoB-100) concentrations, which are important risk factors for the development of cardiovascular disease. Weight loss and endurance exercise improve plasma lipid and lipoprotein concentrations. However, the mechanisms responsible for this effect are largely unknown, and much uncertainty remains regarding the independent roles of dietary energy intake, exercise energy expenditure, and net energy balance in controlling plasma TG concentrations. The main goal of this project, therefore, is to investigate the mechanisms by which acute alterations in energy balance, induced by diet and/or physical activity (endurance exercise), regulate very-low density lipoprotein (VLDL) metabolism. Subjects will be asked to perform 3 separate trials. One of these will always be an "energy balance" trial that will act as the control trial for the other 2 trials they perform. Subjects will therefore be randomized to 2 different study arms.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
PREVENTION
Masking
NONE
Enrollment
12
Subjects will consume over a 24 hour period 33% more calories than they require to meet their energy demands.
Subjects will consume over a 24 hour period 33% more calories than they require to meet their energy demands but will perform 2 hours of exercise that will be sufficient to burn off the excess calories consumed resulting in subjects being in net energy balance.
Subjects will consume over a 24 h period only 66% of the calories required to meet their energy demands such that they will be in a net negative calorie balance in this trial.
Washington University in Saint Louis
St Louis, Missouri, United States
Very Low Density Lipoprotein-Triglyceride and apoB-100 concentrations
Time frame: After acute (24 hour) changes in energy intake and/or energy expenditure
Liver Very Low Density Lipoprotein-Triglyceride and apoB-100 secretion rates
Time frame: After acute (24 hour) changes in energy intake and/or energy expenditure
Liver Very Low Density Lipoprotein-Triglyceride and apoB-100 clearance rates from plasma
Time frame: After acute (24 hour) changes in energy intake and/or energy expenditure
Plasma glucose concentration and turnover rate
Time frame: After acute (24 hour) changes in energy intake and/or energy expenditure
Plasma insulin concentration
Time frame: After acute (24 hour) changes in energy intake and/or energy expenditure
Plasma free fatty acid concentration and turnover rate
Time frame: After acute (24 hour) changes in energy intake and/or energy expenditure
Plasma glucose concentration
Measured hourly over the 24 h period.
Time frame: During acute (24 hour) changes in energy intake and/or energy expenditure
Plasma insulin concentration
Measured hourly over the 24 h period.
Time frame: During acute (24 hour) changes in energy intake and/or energy expenditure
Plasma free fatty acid concentration
Measured hourly over the 24 h period.
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Subjects will consume over a 24 hour period the same amount of calories as ingested in the isocaloric trial but will also perform 2 hours of exercise that will be sufficient to burn off a third of the calories they consumed during this day resulting in subjects being in net negative energy balance in this trial
Subjects will consume over a 24 hour period a sufficient amount of calories to meet their energy needs.
Time frame: During acute (24 hour) changes in energy intake and/or energy expenditure