The effect of nutrients on maximal fat oxidation rates in adult humans measured using indirect calorimetry. (360G-Wellcome-211530_Z_18_Z)

I aim to study the effects of nutrient availability and mitochondrial transport capacity on the variability of maximal fat oxidation (MFO) during exercise in healthy adults. Less than half of MFO can be predicted by variables such as gender, VO2max and body composition. There are two possible reasons for this. First, nutrient availability may have a large effect on MFO and current protocols may not adequately control for it. Second, VO2max - which combines two variables with opposite effects on MFO (oxygen uptake and fat mass) - may not be the optimal predictor. Here, I will test whether heart rates at a given power are a better predictor of MFO and whether short-term fluctuations in nutrient availability can explain some of the variability of MFO seen within the general population. Nutrient availability will be altered using a glucose meal and by glycogen depletion. I will also use nitrate supplementation to test whether MFO can be increased by induced-expression of fat oxidation enzymes. The key goals are to determine to what extent short-term changes in nutrients and the expression of fat oxidation enzymes can alter MFO and whether the resultant fat oxidation rates can be predicted using simple heart rate data.