Fuel from Fat

I recently took some physiological tests to measure my fitness. My intention is to redo these next year and hopefully see some changes as a result  of my training.

I'llg/ do some write ups on these to serve as a reference for the future, starting with the one that surprised me the most.

This was the one that showed where I was getting the energy to cycle from. This will always be a mixture of fat and carbohydrate,  with a greater proportion of fat at lower intensities,  carbohydrates taking over as intensity increases to provide pretty much 100% at peak levels.

The table below shows the results at the key transition point when carbs take over from fat.


Watts             CHO g/h        Fat g/h      CHO kcal/h  Fat kcal/h Total kcal/h     Calc kcal/h
150                   46                 45              188             417              667                540
175                   113               15               465            139              665                630
200                   100               17               410            154              621                720
225                   114               25               470             235             776                810

There are a couple of interesting things in these figures

• The transition from fat burning at 150W to carb burning at 175
• 150-200W consumes the same amount of calories, showing how rough the rule of thumb that calories = kJ is (the last column shows the KJ figure)