Bioenergetics anyone?

          To lay people, the word bioenergetics seems to be an overwhelming jargon.  They may have the impression that the techy word has all the 'bio' prefix in them.  But the concept behind could be put in much simpler terms.  It is nothing but the energy budget of an animal or human beings. But what is an energy budget and what practical use can it have on our everyday life.
          When one talks about budget, one deals with allocation (another big word).  Simply put, how much will you earmark for every activity that you have.  For example, if a college student is given a daily budget of 200 pesos, how much of it goes to transportation, to lunch, to snacks, and to any unpredicted expense.  In the same token, for a given amount of energy from food that one eats/drink, how much of it is digested, assimilated, used in muscular activity such as swimming, running etc.  In aquaculture, this is often applied to the allocation of energy  consumed as feeds.  It is the lookout of the aquaculturist to see to it that the feeds are highly digestible so that a high proportion is assimilated.  The combination of ingredients tells a fish nutritionist what to expect on how it could support growth (if at all) on the basis of the ratio of protein and total energy content of the feed.  Needless to say, there is the best combination/ratio of these two components for best growth (body protein deposition).  The mixture of ingredients may also give an indication on whether more nitrogenous biological waste is expected. based on the quality of the protein.  The higher the quality, the less ammonia wastes are going to be excreted by the aquatic animals.
          But the application of bioenergetics is not confined to aquaculture alone but is of good use in most aspects involving living thing including human beings.  In human beings, the application is mostly on diet and lifestyle.  The whole science of bioenergetics rely on mesurement of each component of the energy budget.  How does one measure digestibility, assimilation, nutrient deposition, waste output.  If one talks about measurements, then it gets complicated especially if one aims to measure a component with as little errors as possible.
          This then is the introduction for my master's students on my subject next semester on the subject Bioenergetics.