L. individual health/fitness

This table might include observation of dietary requirements and the effects of exercise, concepts of carbon/water and caloric intake/output. How have these ideas shifted in generations past? Also, what paradigm shifts might be in the works?

For instance, exhaling CO2 is perhaps the only natural way to lose metabolized carbon. Would seeing excess weight as an exhalation-shortfall provide a more direct intuitive link between ingestion and exercise, for some, than the argument about food's energy content per se? 

Put another way, does the energy-in/energy-out paradigm provide a weaker (i.e. more surprising) link to the relation between weight and exercise than the carbon-exhalation argument above? If so, will we see a paradigm shift toward this direction in the days ahead?