Obesity: Silva AM

Oliveira AM, Oliveira N, Reis JC, Santos MV, Silva AM, Adan L. · Department of Pediatrics, Federal University of Bahia School of Medicine, Salvador, Bahia, Brazil. · Horm Res. · Pubmed #19129712 No free full text.

Abstract: BACKGROUND/AIMS: Metabolic syndrome (MS) and fatty liver disease (FLD) are on the rise. The association between these conditions in Brazilian youth is analyzed. METHODS: 354 subjects (11.2+/-3.1 years) were evaluated. FLD was suspected by ultrasound and computed tomography; weight and MS by BMI z-score and NCEP-ATPIII respectively. RESULTS: Subjects were classified as: group 1 with suspected FLD and group 2 without and group 2 as 'a' (overweight/obese) and 'b' (normal weight). Comparing group 1 with 2a and 2b, differences in age (p=0.016; p=0.075), triglycerides (TG) (p=0.021; p=0.002), insulin (p=0.652; p=0.015) and homeostasis model assessment method of IR (HOMA-IR) (p=0.737; p=0.003) were found. Group 2a was divided into low/high alanine aminotransferase (ALT). A decrease in waist circumference and TG was found going from those with suspicion of FLD to obese with high and low ALT. Insulin and HOMA-IR in group 1 and high ALT were similar. Gender (OR 6.6; CI 1.9-22.5; p=0.025), age (OR 1.3; CI 1.1-1.6; p=0.006), TG (OR 10.4; CI 3.1-34.4; p=0.005) were associated with suspected FLD. For every 10 U/l increase in ALT, there was a 4-fold greater chance of probable FLD (OR 4.01; CI 2.06-9.40; p<0.001). CONCLUSION: Measurements of ALT and TG should be considered as screening for suspected FLD in overweight/obese youth.

Silva AM, Shen W, Wang Z, Aloia JF, Nelson ME, Heymsfield SB, Sardinha LB, Heshka S. · Exercise and Health Laboratory, Faculty of Human Movement, Technical University of Lisbon, 1495-688 Lisbon, Portugal. · Am J Physiol Endocrinol Metab. · Pubmed #15186997 links to  free full text

Abstract: There is renewed interest in Siri's classic three-compartment (3C) body composition model, requiring body volume (BV) and total body water (TBW) estimates, because dual-energy X-ray absorptiometry (DEXA) and in vivo neutron activation (IVNA) systems cannot accommodate subjects with severe obesity. However, the 3C model assumption of a constant ratio (alpha) of mineral (M) to total body protein (TBPro) and related residual mass density (D(RES)) based on cadaver analyses might not be valid across groups differing in sex, race, age, and weight. The aim of this study was to derive new 3C model coefficients in vivo and to compare these estimates to those derived by Siri. Healthy adults (n = 323) were evaluated with IVNA and DEXA and the measured components used to derive alpha and D(RES). For all subjects combined, values of alpha and D(RES) (means +/- SD, 0.351 +/- 0.043; 1.565 +/- 0.023 kg/l) were similar to Siri's proposed values of 0.35 and 1.565 kg/l, respectively. However, alpha and D(RES) varied significantly as a function of sex, race, weight, and age. Expected errors in percent body fat arising by application of Siri's model were illustrated in a second group of 264 adults, including some whose size exceeded DEXA limits but whose BV and TBW had been measured by hydrodensitometry and (2)H(2)O dilution, respectively. Extrapolation of predictions by newly developed models to very high weights allows percent fat error estimation when Siri's model is applied in morbidly obese subjects. The present study results provide a critical evaluation of potential errors in the classic 3C model and present new formulas for use in selected populations.

Shen W, Punyanitya M, Silva AM, Chen J, Gallagher D, Sardinha LB, Allison DB, Heymsfield SB. · Obesity Research Center, St, Luke's-Roosevelt Hospital & Institute of Human Nutrition, Columbia University, College of Physicians & Surgeons, New York, NY, USA. · Nutr Metab (Lond). · Pubmed #19371437 links to  free full text

Abstract: ABSTRACT: BACKGROUND: Despite increasing research and clinical significance, limited information is available on how the visceral and subcutaneous adipose tissue (VAT and SAT) compartments develop during growth and maturation and then vary in volume across the adult lifespan. The present study aimed at exploring how adipose tissue compartments partition across the lifespan. METHODS: Total body VAT and SAT were quantified in an ethnically-diverse cross-sectional sample of healthy subjects ages 5 - 88 yrs [children (5-17 years): males n = 88, BMI percentile (X +/- SD), 61.9 +/- 27.1; females, n = 59, BMI percentile, 60.0 +/- 28.4; adults (>/= 18 yrs): males, n = 164, BMI, 25.6 +/- 3.7 kg/m2, and females, n = 188, BMI, 25.5 +/- 5.4 kg/m2]. Subjects completed a whole-body magnetic resonance imaging scan and images were then segmented for VAT and SAT; total compartment volumes were calculated from respective slice areas. Sex and age distributions were evaluated by generating quadratic and cubic smoothing lines fitted to the data. Plots were developed with and without adjustment for total adipose tissue, ethnicity, and menopausal status in women. VAT and SAT volumes were both larger with greater age. RESULTS: In adulthood, VAT was larger in males than in females with and without adjustment. In contrast, SAT volume was larger in females than in males after entering puberty and sex differences remained, with and without adjustment, across the remaining lifespan. CONCLUSION: Based on observations made in this cross-sectional sample, VAT and SAT volumes were variably larger with greater age across most of the human lifespan, although the relatively small number of children warrants future larger scale studies to validate our observations. Moreover, the pattern and magnitude of adipose tissue "growth" differed between males and females, with the mechanistic basis of this sexual dimorphism only partially understood. These descriptive observations in a large cross-sectional cohort provide an initial foundation for future longitudinal and cohort studies.

Silva AM, Heymsfield SB, Gallagher D, Albu J, Pi-Sunyer XF, Pierson RN, Wang J, Heshka S, Sardinha LB, Wang Z. · New York Obesity Research Center, St Luke's-Roosevelt Hospital, Columbia University Institute of Human Nutrition, College of Physicians and Surgeons, New York, NY, USA. · Am J Clin Nutr. · Pubmed #18689366 No free full text.

Abstract: BACKGROUND: Extracellular water (ECW), a relevant molecular level component for clinical assessment, is commonly obtained by 2 methods that rely on assumptions that may not be possible to test at the time the measurements are made. OBJECTIVE: The aim of the current study was to evaluate the degree of agreement between ECW assessment by the sodium bromide dilution (ECW(NaBr)) and total body potassium (TBK; whole-body (40)K counting) to total body water (TBW; isotope dilution) methods (ECW(TBK-TBW)) in an ethnically mixed group of children and adults. DESIGN: ECW was measured with the ECW(NaBr) and ECW(TBK-TBW) methods in 526 white and African American males and females (86 nonobese children, 193 nonobese adults, and 247 obese adults). Fat mass was assessed with dual-energy X-ray absorptiometry. Multiple regression analysis was used to examine the variables related to between-ECW method differences. RESULTS: Significant but generally small group mean (+/-SD) differences in ECW were found in the obese adults (1.28 +/- 2.54 kg) and children (-0.71 +/- 1.78 kg). The magnitude of the differences was related to mean ECW in obese adults, children, and nonobese adults, and the relations between these variables were modified by sex for nonobese adults. ECW differences were also dependent on age, weight, sex, and race or on interactions between these variables. CONCLUSIONS: Overall, although good between-method agreement was found across the 3 groups, the degree of agreement varied according to subject characteristics, particularly at the extremes of ECW and body weight. We advance a possible mechanism that may link subject characteristics with the degree of agreement between ECW measurement methods and their underlying assumptions.

Oliveira AC, Oliveira AM, Almeida MS, Silva AM, Adan L, Ladeia AM. · Bahian School of Medicine and Public Health, Science Development Foundation of Bahia, Bahia, Brazil. · J Pediatr. · Pubmed #18280837 No free full text.

Abstract: OBJECTIVE: The association between high-sensitivity C-reactive protein (hs-CRP) and alanine aminotransferase (ALT) with clinical/metabolic variables was evaluated in overweight Brazilian children and adolescents. STUDY DESIGN: Oral glucose tolerance test was performed in 407 students (273 overweight/obese, 11.3 +/- 3.1 y). Measurements included body mass index (BMI), waist circumference (WC), blood pressure, lipids, insulin, hs-CRP, and ALT. Overweight/obese was defined using BMI z-score; insulin resistance (IR) by homeostatic model assessment: insulin resistance (HOMA-IR); and metabolic syndrome (MS) in accordance with the modified NCEP-ATPIII. RESULTS: As weight increased, systolic blood pressure (SBP), diastolic blood pressure (DBP), triglycerides (TG), insulin, HOMA-IR, hs-CRP, ALT, ALT, hs-CRP, and AST and the number of MS components (nMSc) also increased (P </= .001 for all). Subjects with hs-CRP and ALT above the median had higher BMI z-score, WC, SBP, DBP, TG, AST, insulin, HOMA-IR, and nMSc than those with both markers below the median (P </= .002 for all). After adjustment for age, sex and ethnicity, BMI z-score (OR, 1.5; CI, 1.38 to 1.86; P < .001), WC (OR,1.3; CI, 1.19 to 1.43; P < .001) SBP (OR, 1.2; CI, 1.03 to 1.38; P = .015), DBP (OR, 1.4; CI, 1.15 to 1.69; P < .001), TG (OR, 1.8; CI, 1.29 to 2.62; P < .001), insulin (OR, 1.4; CI, 1.23 to 1.71; P < .001), HOMA-IR (OR, 1.2; CI, 1.09 to 1.29; P < .001) and nMSc (OR, 2; CI, 1.16 to 3.47; P = .012) were independently associated with high ALT and hs-CRP. For every 5-cm increase in WC and every 1-point increase in BMI z-score, there were a 1.3- and 1.5-fold greater chance of having increased ALT and hs-CRP, respectively. CONCLUSIONS: Simultaneous measurements of ALT and hs-CRP should be considered as a screening test for metabolic syndrome and cardiovascular disease risk factors in overweight/obese children/adolescents.

Minderico CS, Silva AM, Keller K, Branco TL, Martins SS, Palmeira AL, Barata JT, Carnero EA, Rocha PM, Teixeira PJ, Sardinha LB. · Exercise and Health Laboratory, Technical University of Lisbon, Estrada da Costa, 1499-688 Cruz-Quebrada, Portugal. · Br J Nutr. · Pubmed #17894918 No free full text.

Abstract: The objective was to compare measures from dual-energy X-ray absorptiometry (DXA), bioelectrical impedance analysis (BIA) and anthropometry with a reference four-compartment model to estimate fat mass (FM) and fat-free mass (FFM) changes in overweight and obese women after a weight-loss programme. Forty-eight women (age 39.8 +/- 5.8 years; weight 79.2 +/- 11.8 kg; BMI 30.7 +/- 3.6 kg/m2) were studied in an out-patient weight-loss programme, before and after the 16-month intervention. Women attended weekly meetings for the first 4 months, followed by monthly meetings from 4 to 12 months. Body composition variables were measured by the following techniques: DXA, anthropometry (waist circumference-based model; Antrform), BIA using Tanita (TBF-310) and Omron (BF300) and a reference four-compartment model. Body weight decreased significantly ( - 3.3 (sd 3.1) kg) across the intervention. At baseline and after the intervention, FM, percentage FM and FFM assessed by Antrform, Tanita, BF300 and DXA differed significantly from the reference method (P < or = 0.001), with the exception of FFM assessed by Tanita (baseline P = 0.071 and after P = 0.007). DXA significantly overestimated the change in FM and percentage FM across weight loss ( - 4.5 v. - 3.3 kg; P 0.05) from the reference model in any body composition variables. We conclude that these methods are widely used in clinical settings, but should not be applied interchangeably to detect changes in body composition. Furthermore, the several clinical methods were not accurate enough for tracking body composition changes in overweight and obese premenopausal women after a weight-loss programme.

Wang Z, Heshka S, Pietrobelli A, Chen Z, Silva AM, Sardinha LB, Wang J, Gallager D, Heymsfield SB. · Obesity Research Center, St. Luke's-Roosevelt Hospital, Columbia University College of Physicians and Surgeons, New York, NY 10025, USA. · J Nutr. · Pubmed #17634275 links to  free full text

Abstract: A whole body skeletal muscle [(SM); kg] mass estimation model, based on total body potassium [(TBK); mmol] measured by whole body (40)K counting (WBC) was developed (SM = 0.0082.TBK) and validated in adults in a previous study. It is unknown whether the adult TBK SM prediction model is applicable for pediatric use. The aim of this study was to derive and validate a pediatric TBK SM prediction equation. SM measured by MRI was used as the criterion and TBK was measured by WBC. The protocol was completed in 116 healthy children, 66 males and 50 females, 11.7 +/- 3.5 y (mean +/- SD, range = 5-17 y). A strong linear correlation was observed between TBK and SM (r = 0.984; P < 0.001). The SM:TBK ratio was 0.0071 +/- 0.0008 kg/mmol in the children studied, much lower than the corresponding value of 0.0082 kg/mmol in adults. An empirical SM prediction equation was developed using TBK alone: SM = 0.0085.TBK - 2.83, r(2) = 0.97, SEE = 1.39 kg. Bland-Altman analysis did not disclose a significant bias in the prediction of SM. When biological factors entered along with TBK in the general linear model, another prediction equation was developed: SM = 5.52 + 0.001.TBK (mmol) + 0.081.weight (kg) - 0.049.height (cm) + 0.00004.TBK . height + race (-0.60 for Caucasian, 0.49 for African-American, and 0 for Hispanic). Because the adult TBK SM prediction model is not applicable for pediatric use, this study provides new empirical TBK SM prediction equations that should prove useful for studies on nutrition, growth, and development in children.

Minderico CS, Silva AM, Fields DA, Branco TL, Martins SS, Teixeira PJ, Sardinha LB. · Exercise and Health Laboratory, Faculty of Human Movement-Technical University of Lisbon, Estrada da Costa, Portugal. · Eur J Clin Nutr. · Pubmed #17392701 No free full text.

Abstract: OBJECTIVE: This study was designed to compare measured and predicted thoracic gas volume (V (TG)) after weight loss and to analyze the effect of body composition confounders such as waist circumference (WC) on measured V (TG) changes. DESIGN: Prospective intervention study. SETTING: Outpatient University Laboratory, Lisbon, Portugal. SUBJECTS: Eighty-five overweight and obese women (body mass index = 30.0+/-3.5 kg/m(2); age = 39.0+/-5.7 years) participating in a 16-month university-based weight control program designed to increase physical activity and improve diet. METHODS: Body weight (Wb), body volume (Vb), body density (Db), fat mass (FM), percent fat mass (%FM) and fat-free mass (FFM) were assessed by air-displacement plethysmography (ADP) at baseline and at post-intervention (16 months). The ADP assessment included a protocol to measure V (TG) and a software-based predicted V (TG). Dual-energy X-ray absorptiometry (DXA) (Hologic QDR 1500) was also used to estimate FM, %FM and FFM. Maximal oxygen uptake (VO(2) max) was assessed with a modified Balke cardiopulmonary exercise testing protocol with a breath-by-breath gas analysis. RESULTS: Significant differences between the baseline and post-weight loss intervention were observed for body weight and composition (Vb, Db, %FM, FM and FFM), and measures of V (TG) (measured: Delta=0.2 l, P<0.001; predicted: Delta=0.01 l, P<0.010) variables. Measured V (TG) change was negatively associated with the change in the WC (P=0.008), controlling for VO(2) max and age (P=0.007, P=0.511 and P=0.331). Linear regression analysis results indicated that %FM and FM using the measured and predicted V (TG) explained 72 and 76%, and 86 and 90% respectively, of the variance in %FM and FM changes using dual-energy x-ray absorptiometry. CONCLUSIONS: After weight loss, measured V (TG) increased significantly, which was partially attributed to changes is an indicator of body fat distribution such as WC. Consequently, measured and predicted V (TG) should not be used interchangeably when tracking changes in body composition. The mechanisms relating the reduction of an upper body fat distribution with an increase measured V (TG) are worthy of future investigation.

Sardinha LB, Silva AM, Minderico CS, Teixeira PJ. · Exercise and Health Laboratory, Faculty of Human Movement, Technical University of Lisbon, Estrada da Costa, 1499-688 Cruz-Quebrada, Portugal. · Physiol Meas. · Pubmed #17028412 No free full text.

Abstract: The purpose of the present study was to compare body surface area (BSA) estimates using two equations (Dubois and Dubois versus Livingston) and their respective effects on per cent body fat (%BF) obtained with two molecular approaches of body composition analysis, two-compartment (2C) and five-compartment (5C) models. Body composition data using the 2C model were studied in healthy adults, 432 women (body mass index (BMI): 28.3 +/- 4.4 kg m(-2)) and 147 men (BMI: 26.8 +/- 3.9 kg m(-2)), while another sample of 126 women (BMI: 30.4 +/- 3.7 kg m(-2)) was evaluated using the 5C model. Measures of body volume (BV) assessed by air displacement plethysmography, bone mineral content by dual energy x-ray absorptiometry (DXA) and total-body water by deuterium dilution were used to estimate %BF with the 5C model. Comparison of means and linear regression analysis was performed. Using BSA(Dubois), either in 2C and 5C models, BV and %BF estimates were significantly underestimated compared to results obtained using BSA(Livingston) (p < 0.05). BMI was strongly associated with %BF differences using BSA(Dubois) and BSA(Livingston) in both 2C (men: r = 0.90; women: r = 0.88) and 5C models (r = 0.88). Though %BF(Dubois) and %BF(Livingston) were strongly associated (r(2) = 1.000), some variability was observed on %BF differences using BSA(Dubois) and BSA(Livingston). These findings suggest that BSA calculation is critical in BF estimation, supporting the use of a more accurate equation for non-obese and obese subjects.

Ginde SR, Geliebter A, Rubiano F, Silva AM, Wang J, Heshka S, Heymsfield SB. · Weight Control Unit, 1090 Amsterdam Avenue, 14th Floor, New York, NY 10025, USA. · Obes Res. · Pubmed #16076993 No free full text.

Abstract: OBJECTIVE: Patients with moderate and severe obesity, because of their physical size, often cannot be evaluated with conventional body composition measurement systems. The BOD POD air displacement plethysmography (ADP) system can accommodate a large body volume and may provide an opportunity for measuring body density (D(b)) in obese subjects. D(b) can be used in two- or three-compartment body composition models for estimating total body fat in patients with severe obesity. The purpose of this study was to compare D(b) measured by ADP to D(b) measured by underwater weighing (UWW) in subjects ranging from normal weight to severely obese. RESEARCH METHODS AND PROCEDURES: D(b) was measured with UWW and BOD POD in 123 subjects (89 men and 34 women; age, 46.5 +/- 16.9 years; BMI, 31.5 +/- 7.3 kg/m2); 15, 70, and 10 subjects were overweight (25 < or = BMI < 30 kg/m2), obese (30 < or = BMI < 40 kg/m2), and severely obese (BMI > or = 40 kg/m2), respectively. RESULTS: There was a strong correlation between D(b) (kilograms per liter) measured by UWW and ADP (r = 0.94, standard error of the estimate = 0.0073 kg/L, p < 0.001). Similarly, percent fat estimates from UWW and ADP using the two-compartment Siri equation were highly correlated (r = 0.94, standard error of the estimate = 3.58%, p < 0.001). Bland-Altman analysis showed no significant bias between D(b) measured by UWW and ADP. After controlling for D(b) measured by ADP, no additional between-subject variation in D(b) by UWW was accounted for by subject age, sex, or BMI. DISCUSSION: Body density, an important physical property used in human body composition models, can be accurately measured by ADP in overweight and obese subjects.

Oliveira AC, Oliveira AM, Adan LF, Oliveira NF, Silva AM, Ladeia AM. · Bahian School of Medicine and Public Health, Science Development Foundation of Bahia, Salvador, Bahia, Brazil. · Obesity (Silver Spring). · Pubmed #18356840 No free full text.

Abstract: OBJECTIVE: Metabolic syndrome (MS) is on the rise in youth. As high-sensitivity C-reactive protein (hs-CRP) is associated with cardiovascular/metabolic disorders, we evaluated the association between MS and its components and hs-CRP in a sample of Brazilian overweight and obese youth. METHODS AND PROCEDURES: A total of 407 students (229 girls, 273 with excessive weight, 11.3+/-3.2 years) were evaluated. Measurement included BMI, waist circumference (WC), blood pressure, lipids, insulin, and hs-CRP. Excessive weight was defined using BMI z -score; MS by the modified National Cholesterol Education Program-Adult Treatment Panel III. RESULTS: Subjects were classified into two groups: with MS (n=72) and without (n=335). hs-CRP means and medians were higher in MS group (1.41 mg/l vs. 1.06 mg/l, P<0.001; 2.21 mg/l vs. 1.23 mg/l, P<0.001). Associations between hs-CRP quartiles and insulin resistance (IR) (P<0.001), MS (P<0.001), WC (P<0.000), BMI z-score (P<0.001), hypertension (P<0.001), hypertriglyceridemia (P<0.001), and low HDL-c (P=0.023) were significant; adjustment of hs-CRP for BMI z-score eliminated the previous association, except for the number of MS components (nMSc) (P<0.001). Adjusting for homeostasis model assessment method of IR (HOMA-IR) did not eliminate the relation between hs-CRP and MS components. Furthermore, increases in BMI z-score and nMSc were associated with an increased hs-CRP. Excessive weight (odds ratio (OR), 7.9; confidence interval (CI), 4.7-13.4; P=0.000), hypertension (OR, 2.3; CI, 1.3-4.2; P=0.003), and hypertriglyceridemia (OR, 2.3; CI, 1.5-3.7; P<0.001) were independently associated with hs-CRP. DISCUSSION: In youth, hs-CRP is strongly related with MS and its components, and is also determined by the body composition. This association indicates a precocious proinflammatory state.