title: Total body mass, fat mass, fat-free mass, and skeletal muscle in older people: cross-sectional differences in 60-year-old persons.
abstract: OBJECTIVE
  To evaluate body composition parameters, including fat-free mass (FFM), appendicular skeletal muscle mass (ASMM), relative skeletal muscle mass (RSM) index, body cell mass (BCM), BCM index, total body potassium (TBK), fat mass, percentage fat mass (FM), and their differences between age groups and to evaluate the frequency of sarcopenia in healthy older subjects
  
  
  METHODS
  Cross-sectional, nonrandomized study.
  
  
  METHODS
  Outpatient clinic.
  
  
  METHODS
  Ninety-one healthy men and 100 healthy women age 60 and older.
  
  
  METHODS
  FFM, ASMM, FM, and percentage fat mass by whole-body dual-energy x-ray absorptiometry; TBK, BCM, and TBK/FFM ratio by whole body potassium-40 counter.
  
  
  RESULTS
  All lean body mass parameters were significantly (P <.05) lower in subjects age 80 and older than in those age 70 to 79, except ASMM in women. Mean FFM was 4.2 kg (7.3%) lower in men age 80 and older than in those younger than 70 and 2.9 kg (6.8%) lower in women age 80 and older than in those younger than 70. The skeletal muscle mass, reflected by ASMM, decreased more than FFM. This suggests that nonskeletal muscle mass is proportionally preserved during aging. Forty-five percent of men and 30% of women were sarcopenic by definition of BCM index and 11.0% of men and women by definition of RSM index.
  
  
  CONCLUSIONS
  Significant age-related differences exist in body composition of older men and women between age 60 and 95. The greater decrease in TBK and BCM than the decrease in FFM and skeletal muscle mass suggests changing composition of FFM with age. Lack of agreement between two independent sarcopenia indexes suggests that further refinement in the definition of a sarcopenia index is necessary.
authors.affiliation: Department of Clinical Nutrition, Geneva University Hospital, Geneva, Switzerland.
authors.forename: U G
authors.initials: UG
authors.lastname: Kyle
authors.forename: L
authors.initials: L
authors.lastname: Genton
authors.forename: D
authors.initials: D
authors.lastname: Hans
authors.forename: V L
authors.initials: VL
authors.lastname: Karsegard
authors.forename: J P
authors.initials: JP
authors.lastname: Michel
authors.forename: D O
authors.initials: DO
authors.lastname: Slosman
authors.forename: C
authors.initials: C
authors.lastname: Pichard
mesh_terms: D015502:Absorptiometry, Photon; D000273:Adipose Tissue / Q000033:anatomy & histology* / Q000000981:diagnostic imaging / Q000502:physiology*; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D000554:Ambulatory Care Facilities; D001823:Body Composition; D001827:Body Height / Q000502:physiology; D015992:Body Mass Index; D001835:Body Weight / Q000502:physiology; D003430:Cross-Sectional Studies; D015444:Exercise / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000033:anatomy & histology* / Q000000981:diagnostic imaging / Q000502:physiology*; D011188:Potassium / Q000032:analysis / Q000502:physiology; D012016:Reference Values; D014915:Whole-Body Counting
chemical_list: D011188:Potassium