Although bariatric surgery is the most effective weight loss therapy, its musculoskeletal consequences are unclear. Some surgical procedures result in changes in gut hormones known to affect bone health. This study examined bone and body composition together with gut hormones (PYY, GLP1) and adiponectin following bariatric surgery. We present preliminary 24 mth data from 56 obese patients undergoing Diet (n=18), Gastric Banding (GB) (n=10), Gastric Sleeve (GS) (n=21) and Roux-en-Y gastric bypass (RYGB) (n=7).
At 12 months weight change [kg (±SD)] was small in Diet group -5(6), greater in GB -16 (12) and GS -33 (13) and greatest in RYGB -39 (12) P<0.0001. Surgical groups experienced significant bone loss with highest total hip (TH) bone loss for RYGB -8.2 (4) %, followed by GS -5.2 (4) %, GB -1.6 (1.3) %, P <0.0001. Only RYGB group experienced LS bone loss of -5.4 (4) % p=0.0009.
Between 12 and 24 months, despite weight stabilisation or weight regain in all groups, TH bone loss continued reaching -14 (3) % for RYGB and -7 (5) % for GS with no further loss for GB and Diet. There was no further fat mass loss in any surgical group beyond 12 months, however lean mass loss continued in RYGB and GS although non significantly. Adiponectin levels remained significantly raised from baseline at 12 and 24m for RYGB and GS (p<0.0001) and for GB (p=0.025), while at 24 months fasting PYY hormone increased only in RYGB (p=0.04) and decreased in GS (p=0.009) with no change in GB and Diet.
Importantly, participants maintained normal levels of calcium, vitamin D and PTH levels through the study follow-up.
Different weight loss modalities resulted in varied skeletal responses. At 2 years, bone loss was marked in RYGB and GS but absent in GB despite significant weight loss. The musculoskeletal changes associated with RYGB and GS may involve changes in PYY and adiponectin, unrelated to weight loss alone.