OBJECTIVE: Conventional body composition methods may produce biased quanti®cation of fat and fat-free mass in obese subjects, due to possible violation of the assumption of constant (73%) tissue hydration. We used an assumption-free, graphical method for interpreting body weight variation in obesity using bioelectrical measurements. DESIGN: 540 obese subjects with body mass index (BMI) b 31 kgam 2 without apparent edema were compared to 726 healthy subjects with BMI`31 kgam 2 and to 50 renal patients with apparent edema. A subgroup of 48 obese subjects were evaluated again after weight loss (8.6 kg, 3 BMI units) following one-month energy restriction (5 MJad, 1200 kcalad). 32 obese uremic patients were evaluated before and after a dialysis session (3.2 kg¯uid removed). Direct measurements obtained from standard 50 kHz frequency bioelectrical impedance analyzer were used as impedance vectors in the Resistance-Reactance Graph. RESULTS: 1) Impedance vectors of obese subjects could be discriminated from those of edematous patients with 91% correct allocation; 2) A signi®cant lengthening of vectors was observed after¯uid loss of 3 kg in obese subjects; but 3) A body weight loss of about 9 kg after energy restriction was associated with no vector displacement. CONCLUSION: A different impedance vector pattern was associated with body weight loss in obesity due to¯uid removal (vector lengthening) versus an energy-restricted diet (no vector displacement).

Obesity. 2007;15:1933-1943. Objective: Abdominal visceral (VAT) and subcutaneous adipose tissue (SAT) display significant metabolic differences, with VAT showing a functional association to metabolic/cardiovascular disorders. A third abdominal adipose layer, derived by the division of SAT and identified as deep subcutaneous adipose tissue (dSAT), may play a significant and independent metabolic role. The aim of this study was to evaluate depot-specific differences in the expression of proteins key to adipocyte metabolism in a lean population to establish a potential physiologic role for dSAT. Research Methods and Procedures: Adipocytes and preadipocytes were isolated from whole biopsies taken from superficial SAT (sSAT), dSAT, and VAT samples obtained from 10 healthy normal weight patients (7 women and 3 men), with a mean age of 56.4 Ϯ 4.04 years and a mean BMI of 23.1 Ϯ 0.5 kg/m 2 . Samples were evaluated for depot-specific differences in insulin sensitivity using adiponectin, glucose transport protein 4 (GLUT4), and resistin mRNA and protein expression, glucocorticoid metabolism by 11␤-hydroxysteroid dehydrogenase type-1 (11␤-HSD1) expression, and alterations in the adipokines leptin and tumor necrosis factor-␣ (TNF-␣). Results: Although no regional differences in expression were observed for adiponectin or TNF-␣, dSAT whole biopsies and adipocytes, while intermediary to both sSAT and VAT, reflected more of the VAT expression profile of 11␤-HSD1, leptin, and resistin. Only in the case of the intracellular pool of GLUT4 proteins in whole biopsies was an independent pattern of expression observed for dSAT. In an evaluation of the homeostatic model, dSAT 11␤-HSD1 protein (r ϭ 0.9573, p ϭ 0.0002) and TNF-␣ mRNA (r ϭ 0.8210, p ϭ 0.0236) correlated positively to the homeostatic model. Discussion: Overall, dSAT seems to be a distinct abdominal adipose depot supporting an independent metabolic function that may have a potential role in the development of obesity-associated complications.

AIM: To evaluate whether fat distribution plays a role in determining serum leptin concentrations. PATIENTS AND METHODS: One-hundred and forty-seven obese patients, 77 males and 70 females, aged 45.1 AE 13.2 y (mean AE s.d.; range 21 ± 73 y), with body mass index (BMI) ranging from 30 to 55 kgam 2 (mean 42.3 AE 5.9). Ultrasound assessment of the thickness of subcutaneous and preperitoneal fat was carried out and calculation of their ratio as abdominal fat index (AFI), waist ± hip ratio (WHR), body composition by bioelectrical impedance to evaluate the percentage of fat mass (FM%) and total amount of fat (FMKg) were also determined. Plasma leptin was measured by radio immuno assay (RIA). RESULTS: In the whole group of patients, serum leptin concentrations were 37.2 AE 18.4 ngaml (range 6 ± 101.3 ngaml); in spite of BMI values not being signi®cantly different, women had leptin values signi®cantly higher (47.4 AE 17.4 ngaml) (P`0.01) than males (28.1 AE 15.1 ngaml), also after correction for fat mass. The mean thickness of abdominal subcutaneous fat was 33.7 AE 12.9 mm and it was signi®cantly (P`0.001) higher in female (40.9 AE 10.6 mm) than in male (27.1 AE 11.2 mm) patients; preperitoneal thickness was 22.9 AE 7.1 mm, with signi®cantly (P`0.05) higher values in males (24.2 AE 6.8 mm) than in females (21.7 AE 7.3 mm). Accordingly, AFI (in all patients 0.84 AE 0.6) was signi®cantly higher in males (1.09 AE 0.6) than in females (0.56 AE 0.2). In the overall population, leptin concentrations were directly and signi®cantly related to subcutaneous but not preperitoneal fat; they showed a strong inverse relationship with AFI and WHR. When the results were evaluated dividing the patients according to gender, subcutaneous fat thickness showed a stronger association with leptin levels in males than in females, whereas no association was found with preperitoneal fat thickness. Leptin and AFI values were signi®cantly related only in men. WHR values were not correlated with leptin concentrations in either sex. When fat mass was added to the model, subcutaneous fat thickness, AFI and WHR remained independently associated with leptin concentrations. Age and diabetes did not in¯uence these measures. CONCLUSIONS: Fat distribution contributes to the variability in serum leptin in obese patients. In particular, subcutaneous abdominal fat is a determinant of leptin concentration, also independently of the amount of fat mass, whereas the contribution of preperitoneal visceral fat is not signi®cant.

Ghrelin is a gastric hormone that exerts a stimulatory effect on appetite and fat accumulation. Ser(3) octanoylation is regarded as a prerequisite for ghrelin biological activity, although des-octanoylated forms may retain biological functions in vitro. Circulating ghrelin levels are usually low in obesity and in states of positive energy balance. Hence, the aim of our study was to analyze plasma active and serum total ghrelin levels in 20 obese (ages, 22-42 yr; body mass index, 41.3 +/- 1.1 kg/m(2)) and 20 lean subjects (ages, 22-43 yr; body mass index, 22.4 +/- 0.6 kg/m(2)) as well as their relationship to measures of glucose homeostasis, body fat, and resting energy expenditure (REE). The measured/predicted REE percentage ratio was calculated to subdivide groups into those with positive (> or = 100% ) and negative (<100%) ratio values. In obese patients, plasma active (180 +/- 18 vs. 411 +/- 57 pg/ml; P < 0.001) and serum total ghrelin levels (3650 +/- 408 vs. 5263 +/- 643 pg/ml; P < 0.05) were significantly lower when compared with lean subjects. Hence, ghrelin activity, defined as the proportion of active over total ghrelin levels, was similarly reduced in the obese state (6.1 +/- 0.9% vs. 8.4 +/- 1%; P < 0.05). There was a significant correlation between active and total ghrelin (r = 0.62; P < 0.001), and between total ghrelin and insulin (r = -0.53; P < 0.001) or insulin resistance using the homeostatis model of assessment-insulin resistance (r = -0.49; P < 0.001) approach. Significantly higher active ghrelin levels (214 +/- 22 vs. 159 +/- 30 pg/ml; P < 0.05) and ghrelin activity (8 +/- 1.7% vs. 4.9 +/- 0.9%; P < 0.05) were observed in patients with positive compared with negative measured/predicted REE ratio values. Our study shows that obesity is associated with an impairment of the entire ghrelin system. The observation that ghrelin is further decreased in cases of abnormal energy profit adds new evidence to the relationship between ghrelin activity and energy balance in obesity.

OBJECTIVE: To study clinical, anthropometric and metabolic determinants of serum leptin concentrations in a series of patients with a wide range of obesity. SUBJECTS: 400 patients, 116 males and 284 females, aged 44 AE 12.3 years with body mass index (BMI) ranging from 31 to 82 kgam 2 (mean 41.4 AE 7.1). MEASUREMENTS: Energy intake by 7-day recall, resting energy expenditure (REE) by indirect calorimetry, body composition determined by bioelectrical impedance; C index, an anthropometric index of abdominal fat distribution, and waist ± hip ratio (WHR), blood glucose serum leptin concentrations, total cholesterol, high-density lipoprotein (HDL) cholesterol, triglycerides, uric acid, and insulin concentrations HOMA IRI (homeostastis model assessment of insulin resistance index). RESULTS: Leptin concentrations were higher in obese than in normal subjects and in females than in males without differences between diabetic and non-diabetic patients; leptin concentrations were not related to age and showed a strong negative association with energy intake only in the group of women with BMI less than 40. Leptin concentrations showed a direct correlation with BMI and body fat values (expressed either as percentage of total body mass or absolute fat mass) independent of age and sex. After adjustment for fat mass, leptin values higher than predicted were found in women whereas concentrations lower than predicted were found predominantly in men. Leptin showed an inverse correlation with WHR and C-index, the latter persisting also after correction for gender and fat mass. REE, but not REEakg fat-free mass (FFM) was inversely related to leptin also after correction for sex and absolute fat mass. Leptin concentrations were directly associated with HOMA IRI, insulin and HDL cholesterol and inversely associated with triglycerides and uric acid. The relationship of leptin with HOMA IRI was still evident after adjusting for sex but was lost when absolute fat mass was added to the model; HDL cholesterol and triglycerides appeared to be variables independent of leptin concentrations even when both sex and fat mass were added to the model. CONCLUSIONS: In a large group of obese patients (half of whom had severe obesity, gender, BMI and fat mass accounted for the largest proportion of serum leptin concentrations variability. We found that in obese subjects there is an effect of fat distribution on leptin concentrations and that, after excluding variability due to absolute fat mass, patients with a greater amount of abdominal fat have relatively low leptin concentrations which in turn relates to a metabolic pro®le compatible with an increased cardiovascular risk. Women with milder obesity may retain some degree of control of food intake by leptin.

2) who were used as a comparison group. Twenty-nine of the obese adults also participated in three separate short exercise sessions including cycle ergometry, stair stepping, and treadmill walking. Results: The repeatability of SWA estimates in obese subjects was high (r ϭ 0.88, p Ͻ 0.001). The SWA generally underestimated the resting energy expenditure (REE) (1811 Ϯ 346 vs. 1880 Ϯ 382 kcal/d) and highly overestimated the energy expenditure during the exercise sessions in obese individuals. REE estimations by SWA were significantly correlated with fat-free mass (r ϭ 0.88, p Ͻ 0.001). Bland-Altman plots based statistical analysis for the estimated REE, and measured IC showed a low agreement (Total Error Ͼ 20% but Systematic Error Ͻ 5%) between the two methods in obese subjects, although they showed a high correlation and a very good agreement in lean and overweight patients. Discussion: The SWA is an easy to handle, practical, new portable device for measuring energy expenditure. The accuracy of the SWA appeared to be poor in the obese subjects we examined, especially those with high REE both in rest and exercise. We believe that it is necessary to incorporate new, obesity-specific algorithms in the relative software.

TAGIAFERRI, MARIANTONELLA, MARIA ELISA BERSELLI, GIOVANNA CALÒ , ALESSANDRO MINOCCI, GIULIO SAVIA, MARIA LETIZIA PETRONI, GIAN CARLO VIBERTI, AND ANTONIO LIUZZI. Subclinical hypothyroidism in obese patients: relation to resting energy expenditure, serum leptin, body composition, and lipid profile. Obes Res. 2001;9:196 -201. Objective: To evaluate whether subclinical hypothyroidism (SH) affects resting energy expenditure (REE) as well as body composition, lipid profile, and serum leptin in obese patients. Research Methods and Procedures: A total of 108 obese patients with SH defined as normal free thyroxine levels and thyroid-stimulating hormone (TSH) values of Ͼ4.38 U/ml (mean Ϯ 2 SD of the values of our reference group of obese patients with normal thyroid function) were compared with a group of 131 obese patients matched for age, sex, and body mass index (BMI) but with normal TSH levels. We assessed estimated daily caloric intake by 7-day recall, REE by indirect calorimetry, body composition by bioelectrical impedance analysis, serum leptin by radioimmunoassay, and lipid profile (i.e., total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, and triglycerides). Results: All of the variables measured were not different between the euthyroid obese patients and those with SH. In a multiple regression model with REE expressed for kilograms of fat free mass (REE/kgFFM) as a dependent variable and percentage of fat mass, BMI, waist-to-hip ratio, age, TSH, free thyroxine, serum leptin, and caloric intake as independent variables, only percentage of fat mass was significantly correlated with REE/kgFFM in both groups. In the SH group only, BMI, waist-to-hip ratio, age, and TSH were related to REE/kgFFM and explained 69.5% of its variability. After dividing the patients with SH using a cutoff TSH value of 5.7 U/ml, which represents 3 SD above the mean of TSH levels of the group of obese patients with normal thyroid function, only REE/kgFFM was significantly different and lower in the group of more severely hypothyroid patients. Discussion: In patients with obesity, SH affects energy expenditure only when TSH is clearly above the normal range; it does not change body composition and lipid profile. We suggest that, at least in obese patients, evaluation of TSH levels may be useful to rule out a possible impairment of resting energy expenditure due to a reduced peripheral effect of thyroid hormones.

FL increases with the amount of fat mass; the prevalence of FL in normal weight women in comparison to men suggests that this fraction is particularly linked to the amount of subcutaneous fat. Moreover, the correlation of BL with REE and the relationship of FL with food intake favours the view of different biological activities for the two circulating forms of leptin.