Figure 1.

Box plots of glomerular filtration rate (GFR) for lean and obese subjects. In all figures there were 11 observations of GFR from lean subjects (nine from the original lean patients and two from patients who were obese and became lean after surgery) and 13 observations from obese subjects (eight from obese patients presurgery and six from the same cohort 12 months after surgery). (a) Non-normalized GFR (P = 0.003, repeated measures analysis of variance comparing lean with obese). (b) GFR normalized to total body weight (P = 0.002, repeated measures analysis of variance comparing lean with obese). (c) GFR normalized to lean body mass (LBM) (P = 0.27, repeated measures analysis of variance comparing lean with obese; power is approximately 0.65 to show 25% difference assuming same variability)