Basal metabolic rate in morbidly obese patients with non-alcoholic fatty liver disease.

BACKGROUND: Non-Alcoholic Fatty Liver Disease occurs mainly in severly obese patients and its relationship to Metabolic Syndrome is increasingly recognized. The aim of this study was to determine energy production-utilization by measuring the Basal Metabolic Rate in severely obese patients, characterized by NAFLD, with or without Metabolic Syndrome. Then, the role of systemic inflammation was assessed. PATIENTS AND METHODS: Twenty severly obese men with Metabolic Syndrome were compared with a well-matched cohort of patients without Metabolic Syndrome. All showed hepatic steatosis at UltraSonography. Basal Metabolic Rate was measured by indirect calorimetry using a canopy system and single-frequency bio-impedance analysis. Serum Interleukin-6 and fibrinogen levels were measured as markers of inflammation
RESULTS: Basal Metabolic Rate was higher in severely obese patients with Metabolic Syndrome than in those without it: 2,496+/-358 kcal/d vs 2,126+/-253 kcal/d, P = 0 .001. Laboratory findings of concurrent chronic inflammation were also higher in these patients, i.e., Il6 4.35+/-1.34 pg/ml vs 6.23+/-2.1 pg/ml, P = 0.034; fibrinogenemia 285+/-40 mg/dL vs 376+/-91 mg/dL, P = 0.020; these of of cytonecrosis, i.e., AlaninaminoTransferase, equally behaved 32.3+/-7.9 UI vs 65.7+/-28.2 UI, P < 0.001. Visceral adiposity and arterial hypertension were more frequently detected in patients with Metabolic Syndrome.
CONCLUSION: Increased energy expenditure, observed in morbidly obese patients as a consequence of a systemic, low-grade, inflammatory process, may explain progression from obesity to Metabolic Syndrome, independent of the presence of NAFLD. In this context, increased Basal Metabolic Rate may be a clue of Metabolic Syndrome.