The capacity to burn fat as fuel for exercise may have important implications for sporting performance, with dietary fat intake positively influencing this ability. Endurance performance and the ability to burn fat will be measured in women runners following the consumption of 3 diets varying in the amount of fat and carbohydrate.
Dietary fat intake positively influences the ability to burn fat during exercise in women but not men, whereas carbohydrate intake negatively influences fat oxidation in both sexes. The independent nature of dietary fat intake as a predictor of the ability to burn fat in women suggests that in conditions of adequate carbohydrate intake providing additional fat may increase fat oxidation in women whereas it does not in men. It is of interest to explore if indeed women are responsive (i.e., increase in fat oxidation) to short-term increases in dietary fat intake induced by overfeeding (adequate carbohydrate) or if as appears to be the case in men reduced carbohydrate intake as typically employed in high-fat, low carbohydrate dietary studies is also a prerequisite for enhancing fat oxidation in women, and whether this translates into a difference in exercise endurance performance.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
NONE
Enrollment
16
High Fat - Carbohydrate (20%), Fat (65%), Protein (15%)
Normal - Carbohydrate (50%), Fat (35%) and Protein (15%)
Normal + Extra Fat - Carbohydrate (50%), Fat (65%), Protein (15%). Carbohydrate and protein intake identical in absolute amounts to NORMAL, with an additional 30% extra energy coming from fat.
University of Birmingham
Birmingham, West Midlands, United Kingdom
Rates of fat oxidation during exercise
Rates of fat oxidation to be measured via indirect calorimetry during 90 minutes of submaximal exercise
Time frame: 90 minutes of sub-maximal exercise
5km running performance
Time to complete 5km on a treadmill
Time frame: Immediately following measurement of Primary Outcome measure
Change in plasma glucose concentration
Area under the plasma concentration versus time curve (AUC) of glucose
Time frame: 90 minutes sub-maximal exercise
Change in Free Fatty Acid concentration
Area under the plasma concentration versus time curve (AUC) of Free Fatty Acid
Time frame: 90 minutes sub-maximal exercise
Change in plasma glycerol concentration
Area under the plasma concentration versus time curve (AUC) of glycerol
Time frame: 90 minutes sub-maximal exercise
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