Background: Sirtuins (SIRTs), ubiquitous deacetylases, are main regulators of energy homeostasis and metabolism. SIRT1 has a positive impact on obesity, diabetes mellitus, liver steatosis, and other metabolic disorders. Lean subjects have higher expression of SIRT1 in the adipose tissue compared to obese. However, it is not known whether weight loss associates with changes in blood SIRT1. We evaluated the effect of weight loss on circulating SIRT1, metabolic parameters, and body composition.
Methods: Thirty-two obese subjects were studied before and 6 months after BioEnterics® Intragastric Balloon (BIB®) [22 patients, BMI 41.82 ± 6.28 kg/m(2)] or hypocaloric diet [10 patients, BMI 38.95 ± 6.90 kg/m(2)]. Plasma SIRT1, body composition, measures of metabolic syndrome (waist circumference, fasting plasma glucose, blood pressure, HDL cholesterol, triglycerides), and inflammation markers (ESR, CRP, fibrinogen) were recorded.
Results: SIRT1 levels showed a significant increase, together with a significant reduction of BMI, excess body weight, and total fat mass either after BIB or diet intervention. The percent excess body weight loss was 33.73 ± 19.06 and 22.08 ± 11.62 % after BIB and diet, respectively, a trend toward a metabolic and inflammatory amelioration was observed with both treatments. Negative correlation between SIRT1 and % fat mass (BIB, ρ = -0.537, p = 0.017; diet, ρ = -0.638, p = 0.047) was also seen.
Conclusions: The reduction of fat mass associates with increased plasma SIRT1 indicating that, besides tissue levels, circulating SIRT1 is stimulated by a negative caloric balance. The rise of plasma SIRT1 may represent a parameter associating with fat loss rather than weight lowering regardless of the weight reduction system method used.
Keywords: BIB; Fat mass; Obesity; SIRT1; Weight loss.