The association between changes in leptin concentration in adults and concurrent changes in body composition: The Fels Longitudinal Study

Using data from white adults in the Fels Longitudinal Study, changes over a 2 to 6-year period in total body fat (TBF), percent body fat (%BF), fat-free mass (FFM), and leptin concentration (Lep) were determined for 125 men and 132 women. For each variable, data from examinations between 1990 and 1996 were used to calculate each individual's annual rate of change between their first and last exams in the interval. Age groups from 18 to 39 and 40 to 69 years were considered. In each group of men and in younger women, annual rate of change in adiposity was associated with the annual rate of change in Lep (r=0.4 to 0.5). In older women (n=60) a similar pattern of association was observed: however, there was also a negative correlation (r=-0.6) between change in FFM and change in Lep. In women, there was a positive correlation between initial level of TBF or FFM and the annual rate of change in Lep (r=0.2 to 0.3), with the relationship with FFM stronger in older women. When Lep was adjusted for concurrent TBF and changes in adjusted Lep computed, there were no significant correlations between changes in adjusted Lep and %BF in either sex. However, in both groups of men, but not women, there was a positive correlation (r=0.3) between changes in adjusted Lep and changes in FFM. Changes in body composition during adulthood show a complex relationship with changes in Lep.