title: The five-level model: a new approach to organizing body-composition research.
abstract: Body-composition research is a branch of human biology that has three interconnecting areas: body-composition levels and their organizational rules, measurement techniques, and biological factors that influence body composition. In the first area, which is inadequately formulated at present, five levels of increasing complexity are proposed: I, atomic; II, molecular; III, cellular; IV, tissue-system; and V, whole body. Although each level and its multiple compartments are distinct, biochemical and physiological connections exist such that the model is consistent and functions as a whole. The model also provides the opportunity to clearly define the concept of a body composition steady state in which quantitative associations exist over a specified time interval between compartments at the same or different levels. Finally, the five-level model provides a matrix for creating explicit body-composition equations, reveals gaps in the study of human body composition, and suggests important new research areas.
authors.affiliation: Obesity Research Center, St Luke's-Roosevelt Hospital, Columbia University, College of Physicians and Surgeons, New York, NY.
authors.forename: Z M
authors.initials: ZM
authors.lastname: Wang
authors.forename: R N
authors.initials: RN
authors.lastname: Pierson
authors.forename: S B
authors.initials: SB
authors.lastname: Heymsfield
mesh_terms: D000273:Adipose Tissue / Q000033:anatomy & histology; D001823:Body Composition; D001834:Body Water; D001842:Bone and Bones / Q000033:anatomy & histology; D002477:Cells; D004602:Elements; D005109:Extracellular Matrix; D005110:Extracellular Space; D006003:Glycogen / Q000032:analysis; D006801:Humans; D008055:Lipids / Q000032:analysis; D008903:Minerals / Q000032:analysis; D008954:Models, Biological; D009132:Muscles / Q000033:anatomy & histology; D011506:Proteins / Q000032:analysis
chemical_list: D004602:Elements; D008055:Lipids; D008903:Minerals; D011506:Proteins; D006003:Glycogen