@UnieCetterie
the human body is something not very energy efficient.
worse to produce the food for daily intake is already expensive, if you want to double it to produce energy it is far from free energy.
A food calorie on our plate required the consumption of thirteen calories of oil or other fossil energy.
the only viable track is to find out where the energy comes from and how to recover it mechanically
in view of our current capacity in the infinite natural energy sector, I have big doubts
Besides, I think that they did their best to discover how it worked, they have use all possible means and find nothing.
apart from sending her on the ISS I do not see what they could do more
Frankly I've been thinking for years about a logical way of integrating magic into a story about a world like ours, the most logical thing I would find would be that our body would produce it from food or the sun
and even then the most logical would be to get the body more powerful, resistant and enduring for a short period of time
or to regenerate faster, but a fireball, without precise conditions and understanding of the phenomenon would be difficult
in any case a calorie of energy does not multiply by magic
for a calorie to become more than one, it would require a scientific understanding of what is around us, or even mineral materials, chemical to add to create a reaction