The cholestyramine-induced decrease of PYY postprandial response is negatively correlated with fat mass in obese women

Obese patients have decreased fasting and postprandial levels of peptide YY (PYY), an anorexigenic peptide produced by the L cells of the gastrointestinal mucosa. Fatty nutrients are the most powerful stimulus for PYY release. Cholestyramine, an anion exchanger which adsorbs bile salts, reduces digestion of lipids. The aim of the present study was to investigate the effects of cholestyramine or placebo on PYY secretion in obese women administered a high-fat meal [n=8; age: 30.9±2.7 years; BMI: 47.3±3.3 kg/m2]. Postprandial PYY levels in obese women given placebo significantly increased in plasma at 30, 60, 90, and 120 min after meal ingestion. Cholestyramine administration significantly reduced postprandial PYY response at 15, 30, and 60 min. Percent fat mass (FM%) was negatively correlated with the percent increment of plasma PYY concentrations induced by meal administration at 30 min; conversely, there was a positive correlation between FM% and the percent decrement of plasma PYY concentrations induced by cholestyramine at the same time interval. These correlations failed to reach statistical significance when related to BMI. This study implies that in the obese state the altered PYY response to food consumption is a consequence of a dysfunction of L cells, which become less sensitive to the positive feedback effect of lipids.

Growth hormone and lactate responses induced by maximal isometric voluntary contractions and whole-body vibrations in healthy subjects

BACKGROUND

In contrast with maximal voluntary resistance exercise, which is allegedly considered a potent GH stimulus in young subjects, evaluation of GH response to whole-body vibrations (WBV) has yielded conflicting results.

METHODS

The acute effects of WBV alone (test A), maximal voluntary isometric contractions (MVC) (test B), and combination of WBV and MVC (test C) on serum GH and blood lactate (LA) levels were studied in 9 healthy adult males. Muscle soreness was assessed 24 and 48 h after exercise by a visual analogue scale.

RESULTS

GH responses were significantly higher after tests B and C than after test A (GH peaks: 18.8 ± 9.5 ng/ml or 20.8 ± 13.7 ng/ml, respectively, vs 4.3 ± 3.5 ng/ml; p<0.05), with no difference between tests B and C. LA concentrations significantly increased after tests A, B, and C, being significantly higher after tests B and C than after test A (LA peaks: 2.0 ± 0.5 mmol/l or 6.7 ± 2.3 mmol/l, respectively, vs 7.6 ± 0.9 mmol/l; p<0.05). Peak LA values were significantly correlated to GH peaks in the 3 tests (r=0.48; p<0.05). Muscle soreness was significantly higher 24-48 h after tests B and C than after test A, no significant differences being present between tests B and C.

CONCLUSIONS

WBV stimulates GH secretion and LA production, with no additive effect when combined with repeated isometric voluntary contractions. Optimization of protocols based on WBV seems important to maximize the positive effects of this intervention on the somatotropic function.

Energy cost and cardiovascular response to upper and lower limb rhythmic exercise with different equipments in normal-weight and severely obese individuals

AIMS

The purpose of the study was to assess energy expenditure and cardiovascular response to rhythmic activity with 6 machines exercising different arm and leg muscle groups in normal-weight (NW) and obese (OB) individuals.

METHODS

In 16 extremely OB subjects and 15 NW controls, oxygen uptake (VO2), heart rate (HR), blood lactate (LA) concentration and ratings of perceived exertion (RPE) were determined during submaximal rhythmic exercise at different intensities obtained by increasing the frequency of the movement (FOM) with each machine. Peak VO2 (VO2p) for each equipment was determined with incremental tests up to exhaustion, whereas maximal VO2 was estimated at cycle ergometer.

RESULTS

Net energy cost (Enet) of exercise increased (p<0.001) for effect of FOM, in both NW and OB with all equipments. Enet was higher in OB than NW during submaximal exercise with Chest/Back, Shoulder Press/Lat Pull, and Leg Press. Higher VO2p were attained with lower limbs than with upper limbs, in both NW (p<0.001) and OB (p<0.001). At the same VO2 (relative to maximal), HR, LA, and RPE were similar in NW and OB but higher during arm than leg activity (p<0.001), while at the same VO2 (relative to VO2p) no difference was detected.

CONCLUSION

Enet of rhythmic exercise is higher in OB than NW with machines requiring wide displacement of large body segments. For both NW and OB, physiological responses and RPE are importantly affected by the relative activation of involved muscles. LA concentration is an important determinant of RPE, independent of the limb in activity.

Effects of low- and high-intensity exercise training on body composition and substrate metabolism in obese adolescents

The objective was to investigate the effects of a 3- week weight-management program including moderate energy restriction and exercise training at 2 intensities [low intensity (LI): 40% and high intensity (HI): 70% maximal oxygen uptake (V'O(2)max)] on body composition, energy expenditure, and fat oxidation rate in severely obese adolescents. Twenty obese adolescents, aged 15-17 yr (body mass index: 37.5 kg/m(2); 38.2% fat mass) participated in this study. Before starting (week 0, W0) and at the end of the weight-management period (week 3,W3), body composition was assessed by a multifrequency tetrapolar impedancemeter; basal metabolic rate (BMR), energy expenditure, and substrate oxidation rate during exercise and post-exercise recovery by indirect calorimetry. At W3, body mass and fat mass decreased significantly (p<0.005) in all groups, and the decreases were significantly greater in the LI than in the HI group (-8.1±1.6 vs -5.9±1.6 kg and -4.2±1.9 vs -2.3±1.7 kg, p<0.05, respectively). Predicted V'O(2)max, expressed in relative values, changed significantly only in the HI group by +0.010±0.006 l/(kg fat-free mass × min) (p=0.010). By contrast, no significant changes were observed at W3 in BMR, energy expenditure, and substrate oxidation rate during exercise and post-exercise recovery. In conclusion, LI (40% of V'O(2)max) physical activity favors fat oxidation and it seems advisable to encourage obese adolescents to perform LI physical activity which is more feasible and acceptable than intense exercise.

GH responses to two consecutive bouts of whole body vibration, maximal voluntary contractions or vibration alternated with maximal voluntary contractions administered at 2-h intervals in healthy adults

BACKGROUND

Pharmacological or exercise stimuli repeated at a short interval (but not electrical muscle stimulation) are associated with a blunting of GH responsiveness.

AIM

To compare GH responses to repeated bout of three different GH-releasing stimuli.

METHODS

The effects of two consecutive bouts (with a 2-h interval) of whole body vibrations (WBV), maximal voluntary contractions alone (MVC), or alternated with WBV (MVC-WBV) on blood GH and lactate (LA) were assessed in nine young males.

RESULTS

Baseline levels of both GH and LA increased significantly after the first bout of all the tested stimuli, and were significantly lower after WBV than after MVC or MVC alternated with WBV, no difference being detected between these last. The administration of a second bout resulted in significantly lower GH increases than those elicited in the first bout in the three different tests; significantly lower LA responses were recorded after the second bout of MVC and MVC-WBV when compared with those obtained after the first bout, while no significant differences were observed after the two WBV bouts for LA. All responses after the second bout of MVC and MVC-WBV were significantly higher than those observed after WBV alone. GH concentrations were significantly correlated with LA after all stimuli, although LA concentrations after the second bout were associated with markedly lower GH levels.

CONCLUSIONS

A significant blunting of GH responsiveness ensues after a second bout of different GH-releasing stimuli, independent from the amount of GH released after the first bout. This is a pattern also observed for other pharmacological stimuli and exercise modalities, and suggests a common mechanism underlying different GH-releasing stimuli.

Changes in plasma levels of ghrelin, leptin, and other hormonal and metabolic parameters following standardized breakfast, lunch, and physical exercise before and after a multidisciplinary weight-reduction intervention in obese adolescents

OBJECTIVE

To investigate in severely obese adolescents the effects of a 3-week multidisciplinary weight-reduction intervention involving moderate energy restriction, individualised physical activity and behavior therapy on the response of some hormonal and metabolic parameters to meals and exercise.

DESIGN

Clinical longitudinal study on inpatients in a specialised institution.

SUBJECTS

A total of 20 obese adolescents (10 boys and 10 girls) aged 12-17 yr [body mass index (BMI): 37.7±6.1 kg/m2; fat mass (FM): 44.8±13.2 kg].

MEASUREMENTS

The changes in plasma concentration of leptin, ghrelin, GH, IGF-I, insulin, glucose, and non-esterified fatty acids (NEFA) in response to standardised meals and exercise bouts were measured before and after the weight-reduction intervention. At the same times, body composition was assessed by bioelectrical impedance as well as appetite sensations using a visual analog scale.

RESULTS

At the end of the intervention, the adolescents had lost body weight and FM (expressed both in kg and %) (p<0.05), without any significant fat-free mass loss (in % terms). In response to both meals and exercise, after the 3-week intervention, plasma leptin concentration decreased significantly (p<0.05), whereas the other hormones (insulin, ghrelin, GH, and IGF-I) and metabolic parameters (glucose and NEFA) did not change. Interestingly, appetite was not affected by the intervention.

CONCLUSION

This 3-week multidisciplinary intervention in obese adolescents induced a significant body weight loss with beneficial changes in body composition. However, despite there being no change in metabolic parameters and ghrelin in response to meals and exercise after the intervention, plasma concentrations of leptin were decreased. The failure of ghrelin levels to increase by this approach might explain the good control of appetite observed at the end of the study.

The energy cost of cycling and aerobic performance of obese adolescent girls

In order to assess the energy cost of cycling and aerobic capacity in juvenile obesity, responses to cycle ergometer exercise were studied in 10 pubertal obese (OB) [body mass index (BMI) SD score (SDS): 3.40+/-0.58 SD] adolescent girls (age: 16.0+/-1.2 yr) and in 10 normal-weight (NW, BMI SDS: -0.30+/-0.54) girls of the same age (15.1+/-1.9). To this aim, gas exchange, heart rate (HR), and energy expenditure (EE) were studied during graded cycle ergometer test at 40, 60, 80, 100, and 120 W. The energy cost of cycling was higher in OB, being oxygen uptake (VO2) higher (about 20%) in OB than in NW girls at all workloads (p<0.01-0.001). Estimated maximal VO2 and VO2 at anaerobic threshold were significantly (p<0.05) higher in OB girls [although lower per unit body mass (p<0.01) and similar for unit fat-free mass], and explained the higher oxygen pulse and lower HR for any EE observed during submaximal exercise in OB. While net mechanical efficiency (ME) was significantly lower in OB (p<0.01), delta ME was similar in both groups, indicating no substantial derangement of muscle intrinsic efficiency. It is concluded that, despite a higher cost of cycling, OB girls can rely on a larger aerobic capacity which makes them able to sustain this kind of exercise within a wide range of work loads, with relevant implications when planning protocols of physical activity in the context of interventions for the reduction of juvenile obesity.

Metabolic responses to submaximal treadmill walking and cycle ergometer pedalling in obese adolescents

Physical activity is essential in obesity management because of the impact of exercise-related energy expenditure (EE) and fat oxidation (Fox) rate on a daily balance, but the specific physiological effects of different exercise modalities are scarcely known in obese individuals. The objective of the study was to compare the metabolic responses to treadmill (TM) and cycle ergometer (CE) exercise in obese adolescents. Gas exchange, heart rate (HR), blood lactate (LA) concentration, EE and Fox were determined at different intensity levels (up to about 85% of maximal oxygen uptake) during TM and CE in 14 pubertal (Tanner stage: >3) obese (BMI SDS: 2.15-3.86) male adolescents (age: 13-18 years). At comparable HR, oxygen uptake, EE and Fox were higher, and LA lower, during TM than CE (P<0.05-0.001), suggesting that cycling imposes a metabolic involvement at the level of the single active muscles greater than walking. Therefore, due to different physiological responses to TM and CE, walking was more convenient than cycling in obese adolescents, permitting to attain the same EE at lower HR, with lower blood LA concentration and with greater Fox. These conclusions seem clinically relevant when using exercise as a part of multidisciplinary treatment for juvenile obesity and amelioration of related metabolic disturbances.

Factor analysis of metabolic syndrome components in severely obese girls and boys

AIMS AND METHODS

Factor analysis is a multivariate correlation technique frequently employed to characterise the aggregation of abnormalities underlying the metabolic syndrome (MS), but scarcely used in obese adolescents. Aim of the study was to investigate the clustering of anthropometric and metabolic variables related to the MS in 487 obese pubertal adolescents (140 boys, 347 girls) in the range of age 11-18 yr employing the factor analysis with exploratory approach.

RESULTS

Principal component analysis reduced 11 correlated physiological variables to 4 uncorrelated factors that explained 68.7% of the variance in the original parameters in boys, and 68.4% in girls. In boys, these factors were: obesity/ hypertension, insulin resistance, dyslipidemia, and hyperglycemia, with elements related to obesity and fat distribution loaded also in dyslipidemia and insulin resistance. In girls no commonalities were detected, but elements of dyslipidemia and insulin resistance were loaded in a single factor, whereas elements of obesity and hypertension were loaded in separate factors.

CONCLUSIONS

The identification of 4 independent factors suggests a multiple physiological origin of the MS also in youngsters. The measures of adiposity were correlated with development of hypertension, insulin resistance, and dyslipidemic phenomena in boys only, whereas in girls anthropometric measures were not correlated with any tested component of the MS, possibly disclosing the protective effect of female sex hormones in the juvenile age span.

Physical activity ratios for various commonly performed sedentary and physical activities in obese adolescents

The physical activity ratio (PAR) values are commonly used to convert subjects' physical activity recalls into estimates of daily energy expenditure (DEE). A PAR is defined as the ratio between energy expenditure corresponding to a sedentary or a physical activity (kJ/min) and basal metabolic rate [(BMR) kJ/min]. The objective of the present study was to determine the PAR for different sedentary and physical activities in obese adolescents. Thirty-three obese adolescents [mean body mass index: 35.1 kg/m2; 40.3 % fat mass] aged 11 to 17 yr participated in this study. BMR was assessed by indirect calorimetry after an overnight fast by means of an open-circuit, indirect computerised calorimetry with a rigid, transparent, ventilated canopy. Energy expenditures corresponding to various sedentary and physical activities in free-living conditions were determined using a portable metabolic unit, and body composition by bioelectrical impedance analysis (BIA). The PAR of each activity was obtained by dividing the assessed energy expenditure by BMR. In this study, the PAR of various sedentary and physical activities did not vary significantly with sex, age, and body mass. Thus, the data for boys and girls were combined and the PAR for 27 sedentary and physical activities were determined. The PAR values can be applied to determine the mean DEE (kJ) using the specific equation considering BMR (kJ/min), PAR, and duration (min) of each activity performed by the subject during the 24 h. This information will be useful to health-care professionals because estimation of DEE in obese adolescents is necessary in order to prescribe an adequate dietary therapy to induce a desired level of energy deficit.

Prevalence and risk factors of metabolic syndrome in Brazilian and Italian obese adolescents: a comparison study

BACKGROUND

Metabolic syndrome (MS) prevalence between different populations in obese adolescents is scanty to date.

OBJECTIVE

To compare the MS prevalence and related risk factors in Brazilian and Italian obese adolescents.

METHODS

A total of 509 adolescents (110 Brazilian, 399 Italian), aged 15-19 years. Anthropometric characteristics, triglycerides (TG), total, low-density lipoprotein (LDL)-, high-density lipoprotein (HDL)-cholesterol, fasting plasma glucose (FPG), insulin, homeostasis model assessment of insulin resistance (HOMA-IR) and blood pressure were measured.

RESULTS

Age, body mass index (BMI) and BMI z-score were not significantly different between the two subgroups. BMI z-score, TG, FPG, HOMA-IR and systolic blood pressure (SBP) were significantly higher in boys than in girls both in Brazilian and Italian adolescents, while HDL-cholesterol levels were lower in boys than in girls. No significant differences were observed in BMI, LDL and total-cholesterol and DBP in two genders and groups. Insulin, FPG, HOMA-IR and TG were significantly higher, while LDL-cholesterol and SBP were significantly lower in Brazilian than in Italian subjects, both in males and females. HDL and total-cholesterol and diastolic blood pressure (DBP) were not significantly different between the two subgroups and genders. MS prevalence was higher in Brazilian than in Italian obese boys (34.8 vs. 23.6%, p < 0.001) and girls (15.6 vs. 12.5%, p < 0.01). The most frequently altered parameter was HOMA-IR both in subjects with MS (100% in Brazilian and 81.8% in Italian) and without MS (42.9% and 11.7%).

CONCLUSION

Metabolic syndrome represents a worldwide emerging health problem in different ethnical populations, the alterations of the risk factors related to MS (different in their prevalence between different subgroups) being strictly linked to the degree of obesity.

GH responses to two consecutive bouts of neuromuscular electrical stimulation in healthy adults

BACKGROUND

It is well established that repeated GHRH administration or repeated voluntary exercise bouts are associated with a complete blunting of GH responsiveness when the administration of the second stimulus follows the first one after a 2-h interval.

AIM

To evaluate GH responses to neuromuscular electrical stimulation (NMES) in healthy adults.

METHODS

Six volunteers (mean age+/-s.d. 31.7+/-5.5 years) were studied before and after two consecutive bouts of NMES exercise (a series of 20 contractions at the maximum of individual tolerance, frequency: 75 Hz, pulse duration: 400 mus, on-off ratio: 6.25-20 s) administered at a 2-h interval.

RESULTS

Baseline GH levels (mean: 0.3+/-0.2 ng/ml) significantly increased after the first NMES (peak: 4.2+/-3.7 ng/ml), with a complete normalization after 120 min (0.3+/-0.3 ng/ml). The administration of the second bout of NMES of comparable characteristics also resulted in a significant GH increase (peak: 5.2+/-3.2 ng/ml), which was comparable with that observed after the previous one. GH net incremental area under the curve after the first and second bouts of NMES were not significantly different (155.1+/-148.5 and 176.9+/-123.3 ng/ml per h, P=0.785).

CONCLUSIONS

Unlike repeated pharmacological stimuli and voluntary exercise bouts, subsequent sessions of NMES administered at a 2-h interval appear to circumvent feedback mechanisms and to re-induce the GH responses, thus indicating a possible different underlying mechanism elicited by different GH-releasing stimuli.

Exercise-induced effects on growth hormone levels are associated with ghrelin changes only in presence of prolonged exercise bouts in male athletes

AIM

The aim of this study was to evaluate growth hormone (GH) and ghrelin levels in response to physical exercise in athletes.

METHODS

Two different exercise workloads were administered in two different groups of athletes. Group A athletes (19 males, 18 females; mean age +/- standard deviation: 25+/-6.7 years), performing a 60-90 min training session at approximately 80% of VO2max, were sampled for GH and ghrelin determinations before and immediately at the end of a training session on-the-field. Group B athletes (4 males; mean age: 28.2+/-7.2 years) performed two consecutive 30-min cycling sessions at 80% of individual VO2max at different time intervals between bouts (2 and 6 h) in two different days. GH and ghrelin concentrations were determined in blood samples collected at 15-min intervals during exercise and following 1 h of recovery.

RESULTS

In group A athletes, GH levels increased after the training session (P<0.0001), with no differences between males and females. In male athletes, ghrelin levels significantly decreased after the training session (from 1 506.4+/-859 to 1 254.8+/-661.7 pg/mL, P<0.05), while no significant changes were found in females. No correlations were observed between GH and ghrelin levels at rest and after training. In group B athletes, GH levels significantly increased after the first exercise bouts (peak: 26.8+/-11.2 and 17.3+/-3.5 ng/mL, respectively), while the pattern of GH response was different after the second bout of exercise performed at 2-h or 6-h interval. In fact, peak GH concentration in response to the second bout (4.3+/-1.6 ng/mL) was lower (P<0.01) than that of the first bout when the interval elapsed was only 2 h, while a recovery of GH responsiveness was evident after the 6-h interval between the two exercise bouts (11.9+/-3.3 ng/mL). As far as ghrelin levels are concerned, no significant changes were observed during and after the two exercise bouts performed at the different time intervals.

CONCLUSION

GH responses to prolonged exercise bouts (60-90 min) are associated with changes in ghrelin levels only in male athletes, while repeated exercise bouts of lower duration (30 min), capable to determine marked GH responses, are divorced from changes in ghrelin concentrations.

Prediction of resting energy expenditure in severely obese Italian males

The objectives of the present study were to develop and cross-validate new equations for predicting resting energy expenditure (PREE) in severely obese Italian males, and to compare their accuracy with those of the Harris-Benedict, WHO/ FAO/UNU, Huang, Owen, Mifflin, Livingston, Nelson, Bernstein, and Cunnimgham equations in order to predict resting energy expenditure (REE), using the Bland-Altman method. One hundred and sixty-four severely obese males [mean body mass index (BMI): 45.4 kg/m2; 50.2% fat mass), aged 20 to 65 yr participated in this study. REE was measured by indirect calorimetry and body composition by bioelectrical analysis. Equations were derived by stepwise multiple regression analysis using a calibration group and tested against the validation group. Two new specific equations, based on anthropometric [REE=Weight x 0.048 + Height x 4.655 - age x 0.020 - 3.605 (R2=0.68, SE=1.14 MJ/d)] or body composition parameters [REE=fat free mass (FFM) x 0.081 + fat mass (FM) x 0.049 - age x 0.019 - 2.194 (R2=0.65, SE=1.15 MJ/d)], were generated. Mean PREE were not different from the mean measured REE (MREE) (<1%, p<0.001), REE being predicted accurately (95-105% of MREE) in 66 and 62% of subjects, respectively. The Harris-Benedict, WHO/FAO/UNU, Huang and Owen equations showed mean differences lower than 5% and PREE was accurate in less than 30% of subjects. The Mifflin, Livingston, and Nelson equations showed a mean PREE underestimation >7% (p<0.001) and PREE was accurate in less than 25% of subjects. The Bernstein and Cunningham equations showed a greater PREE underestimation (>22%, p<0.001) in more than 85% of subjects. The new prediction equations allow an accurate estimation of REE in groups of severely obese males and result in lower mean differences and lower limits of agreement between PREE and MREE than the commonly used equations.

Comparison of predictive equations for resting energy expenditure in severely obese Caucasian children and adolescents

The objective of the present study was to compare resting energy expenditure (REE) calculated by different predictive equations (McDuffie, Derumeaux, Tverskaya, Schofield, FAO/WHO/ UNU, Harris-Benedict and Lazzer-Sartorio) to REE measured in severely obese Caucasian children and adolescents. Two hundred and eighty-seven obese children and adolescents (121 males, 166 females, mean age: 14.5 yr, mean body mass index (BMI) z-score: 3.3) participated in this study. REE was measured (MREE) by indirect calorimetry and body composition by bioelectrical impedance analysis. The FAO/WHO/UNU equations showed the lowest mean difference between predicted resting energy expenditure (PREE) and MREE (+0.2%, p=ns), but the higher SD (+/-1.16 MJ) and the PREE were accurate in 26% of subjects. The Tverskaya, Derumeaux and Harris-Benedict equations significantly underestimated REE in all children and adolescents (-7.6, -4.1, and -2.4%, respectively, p<0.05), while the Schofield and McDuffie equations overestimated REE (+2.5, +5 and 25%, respectively, p<0.05). By contrast, the Lazzer-Sartorio equations showed the greater agreement and accuracy (in 55% of subjects) between mean PREEs and MREE for all children and adolescents, as well as for boys and girls (+1.6%, p=ns). In conclusion, Lazzer-Sartorio equations showed an accurate estimation of REE in groups of severely obese children and adolescents, resulting in lower mean differences and SD and higher accuracy between PREE and MREE than the other equations considered in this study.

Headache patients in primary care and a tertiary care unit in Zürich, Switzerland

The Headache and Pain Clinic (HPC) is a unit of the Zürich Neurology Department, established in 1966. In the present study demographic features, clinical characteristics and medical management of primary and tertiary care patients were compared in two groups of 181 patients each, seen by general practitioners (GPs) or the HPC, respectively, for primary headaches in 1998. There was a preponderance of women and the socially underprivileged in both samples. Chronic headache was overrepresented in the HPC (44.7%). Loss of work for >2 months was found exclusively in the HPC (9.9%). Of the GP patients, 40% were using triptans and 26.5% in the HPC. One-third of both groups had had complementary and alternative medical treatment. Differences in management strategies reflected differences in headache severity and chronicity. Results indicated that remaining shortcomings of diagnosis and treatment of headache in primary care could be minimized by involving GPs in similar non-commercial studies.

Prediction of resting energy expenditure in severely obese Italian women

The aims of the present study were to develop and cross-validate new equations for predicting resting energy expenditure (PREE) in severely obese Italian women, and to compare their accuracy with those of the Harris-Benedict, Bernstein, WHO/FAO/UNU, Owen, Mifflin, Nelson, Siervo, Huang and Livingston equations to predict REE, using the Bland-Altman method. One hundred and eighty two women [mean body mass index (BMI) 45.6 kg/m2; 56.7% fat mass (FM)], aged 19 to 60 yr participated in this study. REE was measured by indirect calorimetry and body composition by bioelectrical analysis. Equations were derived by stepwise multiple regression analysis, using a calibration group and tested against the validation group. Two new specific equations based on anthropometric REE=Weightx0.042+Heightx3.619-2.678 (R2=0.66, SE=0.56 MJ) or body composition parameters REE=FFMx0.067+FMx0.046+1.568 (R2=0.63, SE=0.58 MJ) were generated. Mean PREE were no different from the mean measured resting energy expenditure (MREE) (<1%, p>0.800) and REE was predicted accurately (95-105% of MREE) in 60% of subjects. The WHO/FAO/UNU, Harris-Benedict and Siervo equations showed mean differences <2% and PREE was accurate in <44% of subjects. The Huang, Mifflin and Livingston equations showed a mean PREE underestimation (>5.0%, p<0.001) and PREE was accurate in <38% of subjects. The Owen, Bernstein and Nelson equations showed a greater PREE underestimation (>14%, p<0.001) in >90% of subjects. The new prediction equations allow an accurate estimation of REE in groups of severely obese women and result in lower mean differences and lower limits of agreement between PREE and MREE than commonly used equations.

Predictors of non-alcoholic fatty liver disease in obese children

OBJECTIVE

To evaluate predictors of non-alcoholic fatty liver disease (NAFLD) in obese children.

DESIGN

Cross-sectional study.

SUBJECTS

Two hundred and sixty-eight obese children not consuming alcohol and without hepatitis B or C were consecutively studied at an auxology clinic.

MEASUREMENTS

Alanine aminotransferase (ALT), aspartate aminotransferase (AST), gamma-glutamyl-transferase (GGT), cholesterol, high-density lipoprotein (HDL)-cholesterol, low-density lipoprotein (LDL)-cholesterol, triglycerides, uric acid, glucose, glucose during oral glucose tolerance testing (OGTT), insulin, insulin during OGTT, insulin resistance as estimated by homeostasis model assessment (HOMA), C-reactive protein (CRP), and systolic and diastolic blood pressure were measured. Fatty liver was diagnosed by ultrasonography using standard criteria. Univariable and multivariable logistic regression was used to evaluate predictors of NAFLD. All predictors except gender and pubertal status were modeled as continuous variables.

RESULTS

NAFLD was detected in 44% of obese children. At univariable analysis, male gender, Z-score of body mass index (BMI) (Z-BMI), ALT, AST, GGT, triglycerides, uric acid, glucose, glucose during OGTT, insulin, insulin during OGTT, HOMA, CRP and systolic blood pressure were predictors of NAFLD, whereas HDL-cholesterol and late-pubertal status were predictors of the normal liver. At multivariable analysis, however, only Z-BMI, ALT, uric acid, glucose during OGTT and insulin during OGTT were independent predictors of NAFLD.

CONCLUSION

Z-BMI, ALT, uric acid, glucose during OGTT and insulin during OGTT are independent predictors of NAFLD in Italian obese children, with most of the prediction explained by ALT and Z-BMI.

The combined effect of adiposity, fat distribution and age on cardiovascular risk factors and motor disability in a cohort of obese women (aged 18-83)

Obesity is associated with a number of serious diseases and with a degree of motor disability, but the extent of the risk and functional derangement within the obese population is not yet completely defined. The study aims to evaluate the combined effect of degree of adiposity, body fat distribution and age on selected cardiovascular risk factors and functional motor disability in a cohort of obese women. A multivariate analysis of variance (MANOVA) is employed to show the combined impact of body mass index (BMI), waist-to-hip ratio (WHR) and age on systolic and diastolic blood pressure (SBP and DBP), total and HDL cholesterol (T-CH and HDL-CH), coronary heart disease (CHD) risk, leg power output (W, assessed with a Margaria test for stair climbing) and subjective general fatigue in a cohort of 463 obese women (BMI range 30.2-66.7 kg/m2; age range 18-83 yr). High WHR and older age, but not BMI, are to a variable degree related to unfavorable values of parameters which contribute to the cardiovascular risk. WHR in the high range is associated with significantly higher values of SBP (p<0.001), CHD risk scores (p<0.001) as well as lower levels of HDL-CH (p=0.01), while older age is significantly associated with higher SBP (p<0.001), T-CH (p<0.001) and CHD risk scores (p<0.001). A significant interaction between age and WHR was detected in the effect on DBP (p=0.01), the negative role of high WHR values being apparent in older women (age > or = 51 yr) but not in younger ones (age < 51 yr). Although not significantly related to CHD risk scores, BMI interacted significantly with WHR in determining high risk score values (p=0.01), the negative effect of a high WHR being apparent in women with a high degree of obesity (BMI > or = 40 kg/m2) but not in those with a low one (BMI < 40 kg/m2). In contrast, WHR did not significantly affect W, which appeared to be mainly dependent on age (p<0.001) and BMI (p<0.001), when considered in terms of unit body mass (BM). Subjective global fatigue, however, was unaffected by any of the factors considered. In the present cohort of obese women, older age and excessive abdominal fat distribution (as assessed by WHR) appear to be significant factors in relation to increased cardiovascular disease risk, irrespective of BMI, while older age and higher levels of overall adiposity are associated with functional motor derangement irrespective of body fat distribution. This suggests that obesity increases metabolic risk and induces motor dysfunction by means of different biological mechanisms and with a different impact within the obese female population.

A follow-up of GH-dependent biomarkers during a 6-month period of the sporting season of male and female athletes

In order to verify the effects of the sporting season (entailing periods of training, competition, recovery, resting) on GH-dependent parameters in male and female athletes from different sporting disciplines, 47 male and female athletes (3 rowers, 5 swimmers, 7 alpine skiers, 3 soccer players, 7 middle distance runners, 14 sprinters, 4 triathletes, 1 road walker, 3 cyclists) were followed-up for a period of 6 months. Blood samples were taken every two months for the evaluation of IGF-I, N-terminal propeptide of type III procollagen (PIIINP) and C-terminal cross-linked telopeptide of type I collagen (ICTP). Abnormal IGF-I, PIIINP and ICTP levels were observed during the follow-up period in 7/100 (7%), 9/100 (9.0%) and 8/100 (8%) samples of the male group, respectively, and in 9/88 (10.2%), 1/88 (1.1%) and 0/88 (0%) samples of the female group, respectively. Abnormal levels appeared to be randomly distributed over the different periods of the sporting season and within male and female subjects, with the large majority of abnormal values being found in the younger athletes. Taking into account all the tests done during the 6-month period (no. 564), individual markers falling outside the normal range (for age) were observed in a small number of instances (34/564 tests done, 24/300 for males and 10/264 for females). When our method for the detection of exogenous recombinant GH (rhGH) administration, based on the concomitant determination of these three peripheral GH-dependent markers and on the attribution of specific scores, was applied in the same athlete at a given time point of the 6-month period, the prevalence of a positive score was extremely low (ie, 3/188 samples or 1.6%). Total positive scores were actually recorded in only three male athletes (2 swimmers and 1 skier, aged <21 yr) at one occasion during the 6-month period considered. In contrast, no total positive scores were found in female athletes (ie, 0/88 samples). In conclusion, the concentrations of IGF-I, PIIINP and ICTP were stable and not significantly modified during 6 months of a sporting season (entailing periods of training, competition, recovery, resting) in athletes from different sporting disciplines. Therefore our method, based on the concomitant determination of three peripheral GH-dependent biomarkers appears safe, acceptable, relatively inexpensive and repeatable (in case of positive or suspected values) immediately or at different intervals of the sporting season. Further additional studies are requested to precise the cut-off values for narrower age-class subdivisions in both genders in order to improve the proposed method.

Age- and gender-related variations of leg power output and body composition in severely obese children and adolescents

A low level of physical activity is considered to be both a determinant factor and a negative effect of childhood obesity, notably contributing to its development and maintenance, but the motor capabilities of obese children of different ages have scarcely been evaluated. The purpose of the study is to depict the general trends of muscle anaerobic performance in a cohort of obese Italian children. Three-hundred-six obese children (141 males, 165 females), aged 10-17 yr with body mass index (BMI) range 28.9-62.0 kg/m2 (mean BMI z-score: 2.71 +/- 0.56 SD; range: 1.6-4.5), were cross-sectionally studied. Lower limb maximal anaerobic power output (W) was assessed with the Margaria stair climbing test, and a consistent subgroup of 77 subjects (37 males, 40 females) was also selected for accessory study of body composition with bioimpedance analysis (BIA), in order to evaluate the relationships between fat-free mass (FFM) and W. In both genders, W increased significantly for effect of age and degree of obesity [three-factor multivariate analysis of variance (MANOVA), p < 0.001], but, while no difference was found between boys and girls in the age groups of 10-11 and 12-13 yr (post-hoc Tukey test, p > 0.05), boys in the age groups 14-15 and 16-17 yr were more powerful than girls of the same age (p < 0.001), wherease the relative W per unit body mass W BM) was higher (two-factor MANOVA) in boys (p < 0.01) of all age groups (p > 0.05). In the subgroup tested with BIA, the amount of FFM increased significantly [two-factor analysis of variance (ANOVA), p < 0.001] according to age, being similar in males and females in lower age groups (post-hoc Tukey test, p > 0.05), but higher in boys of older groups (post-hoc Tukey test, p < or = 0.001), so that all differences between age groups and genders disappeared (two-factor MANOVA) when W was expressed per unit FFM (p > 0.05). A significant linear correlation was found between FFM and W, (R2 = 0.66, p < 0.001). In conclusion, no difference in absolute W can be detected between obese boys and girls up to the age of 13, but W differences observed in older age groups appear to be consistent with a concomitant gender-related variation in body composition. The capability of performing external work in short bursts (as represented by trends in WBM) is lower in girls of all ages, and merits consideration on the clinical ground.

Changes in body composition, physical performance and cardiovascular risk factors after a 3-week integrated body weight reduction program and after 1-y follow-up in severely obese men and women

OBJECTIVE

To investigate the short- and medium-term (ie, at 1-y follow-up) effects of a hospital-based body weight reduction (BWR) program lasting 3 weeks in severely obese individuals.

DESIGN

Longitudinal, clinical intervention study entailing energy-restricted diet, tailored aerobic-strength exercise, psychological counselling and nutritional education during a 3-week period followed by 49 weeks of indirect supervision at home.

SUBJECTS

In all, 45 women and 19 men aged 30.2 +/- 7.2 y (mean +/- s.d.) with severe obesity (BMI: 41.3 +/- 4.3 kg/m(2)), classified as weight losers (final < initial weight) and regainers (final> or =initial weight).

INTERVENTIONS

Body composition, physical performance and cardiovascular risk factors before and after the BWR program and at follow-up.

RESULTS

The large majority of the experimental subjects obtained a clinical success after the 1-y period, and the rate was higher in females (n = 37/45, ie, 82.2%) than in males (n = 11/19, ie, 57.9%). At follow-up, weight losers had higher percent fat-free mass, muscle strength, HDL-cholesterol and self-reported physical activity level and lower total cholesterol and glucose levels than weight regainers (P < 0.05-0.01). Males displayed significantly larger fat-free mass losses than females at post-BWR and at follow-up. CONCLUSIONS A 3-week hospital-based integrated BWR program resulted in a high rate of clinical success in severely obese individuals at 1-y follow-up (particularly in females), that was associated with increased levels of self-reported physical activity and improved muscle strength and lipid profile. Further research is needed to establish the long-term effects (ie, at 2-5 y) associated to this treatment.

Gender-related changes in body composition, muscle strength and power output after a short-term multidisciplinary weight loss intervention in morbid obesity

Obese men and women have notably different body composition, which contributes to a different functional motor impairment, but it is unknown whether they respond differently to the same intervention for body weight (BW) reduction and motor capability improvement. The aim of this investigation was to compare changes in body composition, strength production and power output observed in severely obese men and women after a BW reduction intervention, and to test the hypothesis that changes in body composition may be related to changes in motor functionality. Ninety-five obese men and women of the same age (29.3 +/- 7.0 SD yr) and body mass index (41.2 +/- 4.4 kg/m2) participated in a short-term (3 week) mass reduction program (5 days/week) entailing exercise (aerobic and strength training) and energy-restricted diet. BW and body composition, maximum voluntary total isotonic strength (ST), and maximum leg power output (W) were evaluated before and after the program. After the intervention, BW decreased significantly in both men and women, but males lost a significantly higher amount of their initial BW than females (5.12 +/- 0.91 vs 4.27 +/- 1.42%, p<0.01). In men the BW loss was composed by a similar amount of fat mass (FM) and fat-free mass (FFM), whereas women lost FM almost entirely. Both men and women significantly improved ST after the intervention, but no difference in improvement was detected between genders, while W increased significantly in females (p<0.001), and no change was detected in males, although W per unit BW and FFM increased significantly in both genders (p<0.05-0.001). In spite of the positive correlation of ST and W with FFM (p<0.001), there was no detectable relation between the changes in body composition and those in motor performance, the improvement in ST and W being better attributable to factors other than muscle mass change. The present diet/exercise intervention induced significant effects on BW changes and composition as well as on ST and W, with a different impact in males and females.

Body water distribution in severe obesity and its assessment from eight-polar bioelectrical impedance analysis

OBJECTIVE

To measure body water distribution and to evaluate the accuracy of eight-polar bioelectrical impedance analysis (BIA) for the assessment of total body water (TBW) and extracellular water (ECW) in severe obesity.

DESIGN

Cross-sectional study.

SETTING

Obesity clinic.

SUBJECTS

In all, 75 women aged 18-66 y, 25 with body mass index (BMI) between 19.1 and 29.9 kg/m(2) (ie not obese), 25 with BMI between 30.0 and 39.9 kg/m(2) (ie class I and II obese), and 25 with BMI between 40.0 and 48.2 kg/m(2) (ie class III obese).

METHODS

TBW and ECW were measured by (2)H(2)O and Br dilution. Body resistance (R) was obtained by summing the resistances of arms, trunk and legs as measured by eight-polar BIA (InBody 3.0, Biospace, Seoul, Korea). The resistance index at a frequency of x kHz (RI(x)) was calculated as height (2)/R(x).

RESULTS

ECW : TBW was similar in women with class III (46+/-3%, mean+/-s.d.) and class I-II obesity (45+/-3%) but higher than in nonobese women (39+/-3%, P<0.05). In a random subsample of 37 subjects, RI(500) explained 82% of TBW variance (P<0.0001) and cross-validation of the obtained algorithm in the remaining 38 subjects gave a percent root mean square error (RMSE%) of 5% and a pure error (PE) of 2.1 l. In the same subjects, RI(5) explained 87% of ECW variance (P<0.0001) and cross-validation of the obtained algorithm gave a RMSE% of 8% and a PE of 1.4 l. The contribution of weight and BMI to the prediction of TBW and ECW was nil or negligible on practical grounds.

CONCLUSIONS

ECW : TBW is similar in women with class I-II and class III obesity up to BMI values of 48.2 kg/m(2). Eight-polar BIA offers accurate estimates of TBW and ECW in women with a wide range of BMI (19.1-48.2 kg/m(2)) without the need of population-specific formulae.