non - alcoholic fatty liver disease ( nafld ) is a relevant issue in public health . it represents the most common chronic liver disease in the general population and is expected to increase in the future , as a result of an ageing population , obesity and diabetes . nafld is the hepatic manifestation of metabolic syndrome and includes a spectrum of disease ranging from simple hepatic steatosis to non - alcoholic steatohepatitis ( nash ) , which can progress to cirrhosis . nafld occurs in 6095% of patients with obesity and in 2855% of patients with type 2 diabetes mellitus ( t2 dm ) . insulin resistance ( ir ) , with compensatory hyperinsulinemia , plays a pathogenetic key role in nafld progression . given its low cost , repeatability , safety and availability , ultrasound ( us ) is routinely the first - line imaging technique to detect liver steatosis . central obesity , defined as a presence of excess fat in the abdominal area , is frequently associated with nafld and their coexistence in the same subjects increases the likelihood of having more advanced forms of liver disease . liver steatosis progression is associated not only with the body mass index ( bmi ) , but also with visceral adiposity . however , fat mass and fat distribution can be different in subjects with the same bmi . for these reasons , the body composition ( bc ) evaluation is necessary for assess the nutritional status and the efficacy of nutritional strategies . a valid and precise tool to measuring bc , is the dual - energy x - ray absorptiometry ( dxa ) , an important method for studying not only osteoporosis but also the soft - tissue composition changes . the accuracy of dxa in measuring the fat mass is 98.8% , and combined with other standard anthropometric parameters , it is a reliable tool for the estimation of central fat . the adipose tissue , has been considered an energy storage organ , but over the last decade several findings have encouraged researches on its the endocrine role . furthermore , data highlighted that central adipose tissue is a metabolic and inflammatory organ that modulates the action and the metabolism of brain , liver , muscle and cardiovascular system . recently , the important role of adipokines , peptides synthesized from adipocytes , in the pathogenesis of ir and nafld has been discussed . in particular , adiponectin is considered an anti - inflammatory adipokine , able to reduce body fat , to improve hepatic and peripheral insulin sensitivity , and inversely associated with bmi , ir and hepatic fat accumulation . the aim of this observational study was to investigate , in overweight patients , the possible relationship between central fat mass , liver steatosis and the circulating levels of adiponectin . the study was carried out in overweight patients , referred to the division of clinical nutrition and nutrigenomics , university of rome  tor vergata  of rome ( italy ) , for a nutritional evaluation , in the period january the study was performed in accordance with good clinical practice and complying with the principles laid down of declaration of helsinki . the study was approved by the appropriate ethical committee of the centre , and all patients gave their written informed consent before the recruitment . other exclusion criteria were : insulin therapy , smoking habits , alcohol intake ( > 20 g / day ) , hepatic virus infection , auto - immune diseases , and use of drugs known to induce liver steatosis or nash . after the initial evaluation of 52 patients , 21 ( 40.4% ) were excluded : 5 for heart diseases , 4 for insulin therapy , 2 for hepatitis b virus infection , 6 for excessive daily alcohol intake and 4 for treatment with drugs - inducing steatosis or nash . body weight , height , bmi , and waist circumference were measured according to standard methods . all subjects underwent a biochemical examination of fasting glucose , fasting insulin and alanine aminotransferase ( alt ) . fasting glucose and insulin level were used also to calculate ir , according to the homeostasis homeostasis model assessment ( homa - ir ) . the enzyme - linked immunosorbent assay technique was used to measure fasting serum levels of adiponectin in all patients ( r&d systems inc . the patients underwent us liver by a toshiba eccocee , with a convex transducer of 3.7 mhz . the results were interpreted by an investigator ( la ) with experience in the field . the liver images were considered normal if the texture was homogenous , exhibited fine level echoes and isoechoic compared to the renal cortex and there was adequate visualization of the hepatic vessels and diaphragm ( grade 0 ) . criteria for determining the stage of liver steatosis , in according to the hamaguchi score , included : presence of bright echoes or increased hepato - renal contrast indicative of mild steatosis ( grade 1 ) ; presence of both bright echoes and increased hepato - renal contrast as well as vessel blurring indicative of moderate steatosis ( grade 2 ) ; severe steatosis was considered when in addition to the criteria for moderate steatosis , there was evidence of posterior beam attenuation and non - visualization of the diaphragm ( grade 3 ) . bc was assessed by dxa ( lunar dpx - iq ; ge medical systems , milwaukee , wi ) , according to the standardized described procedure . standard dxa quality control and calibration measures , were performed prior to each testing session . the test takes about twenty minutes , and the subjects remain in a supine position during the scanning . the results , were transmitted to a connected computer for further analysis , according to the manufacturer orientation . in order to show the relation between dxa parameters and us stage of nafld , we displayed graphically the evolution of these features among classes , and we assessed the statistical significance of clinical and laboratory features . statistical differences of laboratory and clinical variables between the four groups were evaluated by the anova test . body weight , height , bmi , and waist circumference were measured according to standard methods . all subjects underwent a biochemical examination of fasting glucose , fasting insulin and alanine aminotransferase ( alt ) . fasting glucose and insulin level were used also to calculate ir , according to the homeostasis homeostasis model assessment ( homa - ir ) . the enzyme - linked immunosorbent assay technique was used to measure fasting serum levels of adiponectin in all patients ( r&d systems inc . the patients underwent us liver by a toshiba eccocee , with a convex transducer of 3.7 mhz . the results were interpreted by an investigator ( la ) with experience in the field . the liver images were considered normal if the texture was homogenous , exhibited fine level echoes and isoechoic compared to the renal cortex and there was adequate visualization of the hepatic vessels and diaphragm ( grade 0 ) . criteria for determining the stage of liver steatosis , in according to the hamaguchi score , included : presence of bright echoes or increased hepato - renal contrast indicative of mild steatosis ( grade 1 ) ; presence of both bright echoes and increased hepato - renal contrast as well as vessel blurring indicative of moderate steatosis ( grade 2 ) ; severe steatosis was considered when in addition to the criteria for moderate steatosis , there was evidence of posterior beam attenuation and non - visualization of the diaphragm ( grade 3 ) . bc was assessed by dxa ( lunar dpx - iq ; ge medical systems , milwaukee , wi ) , according to the standardized described procedure . standard dxa quality control and calibration measures , were performed prior to each testing session . the test takes about twenty minutes , and the subjects remain in a supine position during the scanning . the results , were transmitted to a connected computer for further analysis , according to the manufacturer orientation . in order to show the relation between dxa parameters and us stage of nafld , we displayed graphically the evolution of these features among classes , and we assessed the statistical significance of clinical and laboratory features . statistical differences of laboratory and clinical variables between the four groups were evaluated by the anova test . clinical and laboratory characteristics of the patients , stratified on the basis of the us stage of nafld , are reported in table i. of the 31 patients included in the study , 13 were male ( 41.9% ) . the median value of anthropometric parameters assessed were : bmi 31.45.9 and waist circumference 97.216.2 cm , with 16 patients ( 7 males ) that presented central obesity , according to the definition of the national cholesterol education program adult treatment panel iii ( ncep atp iii ) . us evaluation of the liver showed that : in 8 patients ( 25.8% ) steatosis was absent , in 9 ( 29% ) mild ( grade 1 ) , in 6 ( 19.4% ) moderate ( grade 2 ) , and in 8 ( 25.8% ) severe ( grade 3 ) . the median value of alt was 33.627.3 ul-1 , with four patients that reported high alt value , one without , two with mild and one with severe us liver steatosis . of all dxa parameters analyzed , those that present a statistical significant difference between the us stages of nafld were ( figure 1 ) : abdominal fat ( af , % ) , mean value 42.611.9 ( p<0.05 ) ; abdominal tissue mass ( atm : fat plus lean mass , kg ) , ( mean value 72.5 , p<0.05 ) ; abdominal fat mass ( afm , kg ) , ( mean value 3.91 , p<0.05 ) . considering the only distribution of l2l5 fat tissue ( kg ) , ( mean value 5.21.2 ) , we observed that the value was higher , but reached no statistical significance , in patients with moderate and severe steatosis , compared to those with the mild type . the assessment of ir by homa - ir , showed a statistically significant increase of insulin level , related to steatosis progression ( p<0.05 ) . finally , the concentration of adiponectin ( 7.782.2 g / ml ) , was significantly lower in the advanced us stages of nafld ( p<0.05 ) . obesity , which is often associated with ir , represents a chronic low - grade inflammatory state , characterized by elevated circulating levels of cytokines and activation of pro - inflammatory signaling pathways . in particular , ir plays a key role in the pathogenesis of nafld , causing alterations in the uptake , degradation or secretion of lipid molecules , with consequent accumulation of lipid in the hepatocytes . nafld is usually prevalent in obese subjects , and several studies have reported that regional fat distribution associated with ir is an important factor for development and progression of liver steatosis . in our study , abdominal fat accumulation and anthropometric parameters , increased with us severity of liver steatosis and ir . in this context the first observation is that by using dxa , we quantified the regional distribution of adipose tissue and we found the association between increased central fat mass , and liver steatosis severity . this observation is in agreement with the progression of the values of bmi and circumference observed in our series . concerning the relationship between bc and nafld , this study has shown that central fat accumulation constitutes an important determinant of liver steatosis in overweight patients , independently to bmi . recent data document that the abdominal adipose tissue is an active endocrine organ capable to secrete a multitude of hormones , cytokines , chemokines , and enzymes , collectively known as adipokines . in particular adiponectin , leptin , resistin , visfatin and pro - inflammatory cytokines , such as tumor necrosis factor- , and interleukins , have been shown to be involved in pathogenesis and progression of nafld . the increased number of abdominal adipocytes produces a disequilibrium in adipokines secretion , which promotes liver fat accumulation , and subsequently the development of nafld . in particular , adiponectin improves muscular and hepatic insulin sensitivity , through its anti - inflammatory and anti - atherogenic activity , and its ability to decrease triglyceride synthesis and stimulate -oxidation . in fact adiponectin protects hepatocytes from triglycerides accumulation by increasing -oxidation of free fatty acid and/or decreasing de novo free fatty acid production in hepatocytes . adiponectin levels are reduced in obese patients , and t2 dm , and the plasma concentrations are inversely related to body weight , especially to visceral adiposity . moreover , adiponectin is inversely associated with other traditional cardiovascular risk factors , such as blood pressure , low - density lipoprotein cholesterol and triglyceride levels , and is positively related to high - density lipoprotein cholesterol levels . in our cohort , us liver steatosis progression is characterized by ir and low adiponectin serum levels , pathogenetic factors that can increase the concentrations of intra - cellular fatty acids , and may enhance oxidative stress that is the second stage in the pathogenesis of nash . bc assessed by anthropometry and dxa , may be used as indicator of nafld severity in overweight patients . however , further studies are required to better understand not only this correlation , but also to define the pathogenetic role of central fat distribution and the changes in adipokine levels in the progression of nafld .
aimnon - alcoholic fatty liver disease ( nafld ) is the most common chronic liver disease in the general population . 
 overweight is a common condition in patients with nafld , and body composition ( bc ) assessment is useful to evaluate nutritional status and the efficacy of nutritional strategies . 
 a valid tool for assessing bc is dual - energy x - ray absorptiometry ( dxa ) . 
 adiponectin has been shown to be relevant to the pathogenesis of nafld . 
 the aim of this observational study is to define the relationship between the severity of nafld , the central fat mass evaluated by dxa , and the circulating levels of adiponectin.methodsthe study was carried out in 31 overweight patients . 
 the degree of liver steatosis was evaluated by ultrasound ( us ) examination . 
 anthropometric parameters were measured according to standard methods . fasting glucose and insulin level were used also to calculate insulin resistance ( ir ) , according to the homeostasis model assessment - insulin resistance ( homa - ir ) . 
 the enzyme - linked immunosorbent assay technique was performed to dose fasting serum levels of adiponectin.resultsnafld progression was signicantly associated with increased central fat ( p<0.05 ) . using dxa , we quantified the regional distribution of adipose tissue and found the expected association between central fat and the us severity of nafld . 
 serum levels of adiponectin , were inversely related to nafld progression ( p<0.05).conclusionbc evaluated by anthropometry and dxa , may be used as indicator of nafld severity in overweight patients . 
 the evaluation of bc in clinical practice , can improve the nutritional strategies and follow - up . in the clinical setting adiponectin 
 may represent a potential marker for the staging of nafld .