The problem is that it is overly simplistic. It is similar to saying "running a marathon is just a thermodynamic problem, expend 2500 calories in a single direc

The problem is that it is overly simplistic. It is similar to saying "running a marathon is just a thermodynamic problem, expend 2500 calories in a single direction and you can do a marathon." Sure, that's true, but that's not the hard part. Existing at a caloric delta long enough to meet your goal is the problem!