 The calorimeter measured human metabolism by analyzing the heat produced by a person performing certain physical activities; in 1896 they began the first of what would accumulate into close to 500 experiments.Through their experiments, they were able to create a system - which became known as the Atwater system, to measure the energy in units, known as food calories.With the machine, the dynamics of metabolism could be quantified and the relationship between food intake and energy output could be measured.