 He based the standards off of average intakes, but did not regard them as quantitatively accurate; they logically varied based on age, sex, and activity level but he stressed that they were not metabolic studies.He went on to conduct metabolic studies related to the dietary standards, based off of observations from his work with Voit, who had used a Rubner respiration calorimeter to conduct similar experiments on small animals.Together with Charles Ford Langworthy, they compiled a digest of close to 3,600 metabolic experiments as a primer to the research they would conduct.