The purpose of the discussion in Marley 230 is to learn the conservation of energy equation and how the in and out terms fit into the conservation of energy equation. We will define the terms in the conservation of energy equation. The useful energy in food is called metabolizable energy. The caloric content of food only includes the metabolizable energy. The other energy is lost in feces and urine, and for this analysis, we can consider that energy in feces and urine never enters the body.
Fecal energy remains in the digestive tract and is never used by the body before excretion.
The conservation of energy equation for the body is in the same form as for all other systems that will be studied during the semester. The Change in storage term is change in mass of fat and muscle Note that M is negative because energy is lost from the body due to metabolism. Also note that the body stores excess energy as fat or muscle. The body stores 1 lb of fat for every 3,500 calories that are not burned by metabolism. The change in storage term in the conservation of mass equation can be used to calculate final mass.