Inadequacy of Vitamin D Does Not Interfere with Body Weight Loss in Women of Reproductive Age after Roux-en-Y Gastric Bypass

Objective: To assess the influence of vitamin D on body weight loss in women who had previously undergone Roux-en-Y gastric bypass (RYGB). Methodology: This is an analytical, longitudinal and retrospective study comprising 40 women of reproductive age who had previously undergone RYGB. To investigate the influence of the serum concentrations of vitamin D on body weight reduction, the variables were analyzed in the pre-operative period (T0), in the first (T1) and in the second postoperative year (T2) and were stratified according to the BMI measured in T1 and T2. In addition, in the pre-operative period, participants were subdivided into groups based on adequacy (G1), deficiency (G2) and insufficiency (G3), according to their serum concentrations of vitamin D. Results: Although weight loss occurred in a substantial way in T1, it continued to decrease in T2 (p = 0.017). The women who reached normal weight within two years of surgery showed the lowest vitamin D concentrations preoperatively when compared to those who were overweight (p = 0.011). Women with preoperative vitamin D deficiency showed increased concentrations in the assessed times (p < 0.001), while the opposite (p = 0.001) occurred in women with adequacy. Conclusion: The study showed that inadequacy of vitamin D does not interfere with weight loss in the two-year-follow-up after RYGB and highlights that vitamin D can present a differentiated response postoperatively, to the detriment of the pre-operative period.