Collection and interpretation of plasma leptin concentration data in humans

JENSEN, MICHAEL D, DONALD HENSRUD, PETER C. O’BRIEN, AND S0REN NIELSEN. Collection and interpretation of plasma leptin concentration data in humans. Obes Res. 1999;7:241-245. Objective: To reassess the relationship between body fat and plasma leptin concentrations when a) replicate measures of leptin are made; b) energy intake is controlled at isoenergetic levels before the study; and c) body fat and percent body fat are measured with dual energy X-ray absorptiometry (DXA). Research Methods and Procedures: Two separate studies were conducted. In the first study, four plasma samples were collected for measurement of leptin over 30 minutes on a single day in 43 lean and obese men and women. For the second study, plasma samples were collected on four consecutive days from a group of 50 lean and obese men and women. Percent body fat (and body fat mass) was related to log-transformed mean plasma leptin concentrations using linear regression analysis; multiple linear regression analysis was used to determine whether there was an effect of gender on this relationship, and the analysis of Choi was used to examine whether percent body fat or body fat mass better predicts plasma leptin concentrations. Results: For the first study, percent body fat was highly correlated (r= 0.96, pleptin concentrations. No difference in the relationship between leptin and percent body fat in men and women was detected. The second study confirmed this observation; the relationship between In leptin and percent body fat was virtually identical (r= 0.93, pleptin concentration than body fat mass. The use of multiple (as opposed to a single) leptin