Fig. 2

OPLS-DA cross-validated scores plots of urinary ¹H NMR spectra of the RYGB patients from cohort 1 at pre-op, 2–6 months and 1–2 years post-op (A, Q²Y = 0.27; R²X = 17.2%; R²Y = 56.3%, CVANOVA p = 2.04 × 10⁻¹⁵), and cohort 2 at pre-op and 6-month post-op (B, Q²Y = 0.46; R²X = 25.3%; R²Y = 97.0%, p = 0.02). The metabolites that significantly contributed to the classification of different time points are shown in the heatmap (C). The correlation coefficient (r) was derived from OPLS-DA models and a positive correlation indicates higher relative concentrations of the metabolites in post-op compared to pre-op or in RYGB compared to LGB. q, the corrected p values using Benjamini-Hochberg multiple test correction are shown as #q < 0.0001, ‡q < 0.001, †q < 0.005, *q < 0.05. ^ap < 0.05 and q>0.05. ^{^} putatively assigned metabolites