Baseline TSH levels and short-term weight loss after different procedures of bariatric surgery

Background: Bariatric surgery is a valuable therapeutic option in the treatment of obesity but the outcomes show a large subject-to-subject variability yet to be explained. Thyroid function may represent an involved factor and we have only few controversial data about its influence. Subjects/methods: We retrospectively assessed using a longitudinal approach the relation between baseline TSH levels and short-term (6 and 12 months) weight loss in 387 euthyroid patients who underwent laparoscopic gastric banding (LAGB; n?=?187) or sleeve gastrectomy (SG; n?=?200). Results: After LAGB, patients with low-normal TSH levels (0.40–1.40?mUI/L) had higher percent total weight loss, ?BMI and percent excess weight loss when compared to patients with normal (1.41–2.48?mUI/L) and high-normal (2.49–4.00?mUI/L) TSH (p?<?0.05). Conversely, no association was detected after SG (p?=?0.17). The multivariable regression analysis showed that also baseline BMI (6–12 months) and HOMA2-IR (only at 6 months) were independently associated with the outcomes. Conclusions: TSH levels may influence the short-term weight loss response after LAGB. The lack of association after SG suggests that the influence of baseline endocrine and metabolic factors may not be relevant for procedures with greater and more immediate calorie intake restriction.