Gestational weight gain in overweight and obese women enrolled in a healthy lifestyle and eating habits program.

OBJECTIVES: To determine whether changes in lifestyle in women with BMI > 25 could decrease gestational weight gain and unfavorable pregnancy outcomes. METHODS: Women with BMI > 25 were randomized at 1st trimester to no intervention or a Therapeutic Lifestyle Changes (TLC) Program including diet (overweight: 1700 kcal/day, obese: 1800 kcal/day) and mild physical activity (30 min/day, 3 times/week). At baseline and at the 36th week women filled-in a Food Frequency Questionnaire. OUTCOMES: gestational weight gain, gestational diabetes mellitus, gestational hypertension, preterm delivery. Data stratified by BMI categories. RESULTS: Socio-demographic features were similar between groups (TLC: 33 cases, CONTROLS: 28 cases). At term, gestational weight gain in obese women randomized to TLC group was lower (6.7 ± 4.3 kg) versus controls (10.1 ± 5.6 kg, p = 0.047). Gestational diabetes mellitus, gestational hypertension and preterm delivery were also significantly lower. TLC was an independent factor in preventing gestational weight gain, gestational diabetes mellitus, gestational hypertension. Significant changes in eating habits occurred in the TLC group, which increased the number of snacks, the intake of fruits-vegetables and decreased the consumption of sugar. CONCLUSIONS: A caloric restriction associated to changes in eating behavior and constant physical activity, is able to reduce gestational weight gain and related pregnancy complications in obese women.

Lifestyle and nutrition related to male longevity in Sardinia: an ecological study.

BACKGROUND AND AIMS: A demographic analysis in the Mediterranean island of Sardinia revealed marked differences in extreme longevity across the 377 municipalities and particularly identified a mountain inner area where the proportion of oldest subjects among male population has one of the highest validated value worldwide. The cause(s) of this unequal distribution of male longevity may be attributed to a concurrence of environmental, lifestyle and genetic factors. METHODS AND RESULTS: In this study we focussed on some lifestyle and nutrition variables recorded in the island's population in early decades of 20th century, when agricultural and pastoral economy was still prevalent, and try to verify through ecological spatial models if they may account for the variability in male longevity. By computing the Extreme Longevity Index (the proportion of newborns in a given municipality who reach age 100) the island's territory was divided in two areas with relatively higher and lower level of population longevity. Most nutritional variables do not show any significant difference between these two areas whereas a significant difference was found with respect to pastoralism (P = 0.0001), physical activity estimated by the average slope of the territory in each municipality (P = 0.0001), and average daily distance required by the active population to reach the usual workplace (P = 0.0001). CONCLUSION: Overall, these findings suggest that factors affecting the average energy expenditure of male population such as occupational activity and geographic characteristics of the area where the population mainly resides, are important in explaining the spatial variation of Sardinian extreme longevity.

Nutritional care routines in Italy: results from the PIMAI (Project: Iatrogenic MAlnutrition in Italy) study.

BACKGROUND/OBJECTIVES: Disease-related malnutrition is a common comorbidity at hospital admission. The purpose of the present report was to describe the data on nutritional care routines collected during the Project: Iatrogenic MAlnutrition in Italy (PIMAI) study, as these may be helpful to avoid iatrogenic malnutrition and improve nutritional policies. SUBJECTS/METHODS: Standards of nutritional care were assessed on the basis of (1) adherence to study protocol (completeness of data collected); (2) attitude in assessing the nutritional status; (3) prescription of nutritional therapy (within 3 days) at least in patients presenting with overt malnutrition (body mass index (BMI) <18.5 kg/m(2) or significant weight loss (>or=10% in 3 months and/or >or=5% in the last month)), regardless of its adequacy, and adherence to current guidelines and (4) attitude in monitoring nutritional status during the stay (number of weight measurements performed compared with those expected). RESULTS: In total, 1583 subjects were assessed. A minimum data set for performing the Nutritional Risk Screening 2002 tool was available in 1284 patients (81.1%), but nutritional screening was possible in every patient by alternative analytical criteria related to food intake, anthropometry and biochemistry. However, several missing values were recorded, particularly in biochemical parameters due to lack of prescription by admission wards. According to ward practices, only 38.2% of the patients had the BMI calculated. A nutritional support was prescribed only to 26/191 patients (13.6%) presenting with overt malnutrition. Finally, we recorded that only 21.6% of the patients (207/960 were randomly selected) had their weight monitored on a scheduled basis. This reality was worse in surgical rather than medical departments (17 vs 26%; P<0.001). CONCLUSION: Present results confirm that in Italy, nutritional care routines are still poor and need improvements.

Growth: healthy status and active food model in pediatrics.

OBJECTIVE: The brain integrates peripheral signals of nutrition in order to maintain a stable body weight. Nutritional status defined as the results of introduction, absorption, and utilization of the nutrients could be interpreted with the base of the relationship between nutritional status and healthy status. In this view, energy balance, body function, and body composition are three entities correlated to each other to the healthy status. AIM: To discuss the nutritional status in relation with healthy status, and its relationship with growth and nutrients. METHODS: A review of the available literature on food patterns and active food model was carried out. RESULTS: In the reviewed studies, strategies that could offer promising results to prevent overweight and obesity were discussed, in particular in the light of functional foods that effect energy metabolism and fat partitioning. CONCLUSION: At this moment it is necessary to proactively discuss and promote healthy eating behaviors among children at an early age and empower parents to promote children's ability to self-regulate energy intake while providing appropriate structure and boundaries around eating.

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.

Relationship between body mass index and insulin measured during oral glucose tolerance testing in severely obese children and adolescents.

PRIMARY OBJECTIVE: The study evaluated the accuracy of body mass index (BMI) in detecting hyperinsulinaemia during oral glucose tolerance testing (OGTT) in severely obese children. RESEARCH DESIGN: A cross-sectional study was carried out. MATERIALS AND METHODS: A total of 118 obese children and adolescents (49 females and 69 males) aged 6-19 years were consecutively studied at an outpatient paediatric clinic. Hyperinsulinaemia was defined as a value of log-transformed fasting insulin >/= 80th percentile and OGTT hyperinsulinaemia as a value of the log-transformed area under the curve (AUC) of insulin >/= 80th percentile. The study hypothesis was tested using a logistic regression model with hyperinsulinaemia as the outcome variable and the z-score of BMI corrected for age (z-BMI(age)) as the predictor variable. Receiver-operator characteristic (ROC) curves were used to evaluate accuracy. RESULTS: The mean (SD) BMI for age of the children was 28.6 (4.0) kg m(-2), corresponding to 2.2 (0.5) standard deviation scores. The odds ratio (OR) of OGTT hyperinsulinaemia was 2.0 (95% CI 1.2-3.3; p = 0.007) for each unit increase of z-BMI(age) and the corresponding ROC-AUC was 0.74 (95% CI 0.61-0.86; p = 0.0001). In comparison, the OR of fasting hyperinsulinaemia was 1.1 (95% CI 0.7-1.7; p = 0.716) for each unit increase of z-BMI(age) and the corresponding ROC-AUC was 0.49 (95% CI 0.35-0.62; p = 0.863). CONCLUSION: BMI is reasonably accurate in detecting OGTT hyperinsulinaemia in severely obese children.

Body water distribution and disease.

The study of body water distribution between extra- and intra-cellular spaces has the potential to improve our knowledge on the mechanisms of disease. A major challenge is that of establishing whether commonly detected subclinical alterations of body water distribution have prognostic or clinical implications.

Body mass index is a good predictor of an elevated alanine transaminase level in the general population: hints from the Dionysos study.

AIM: To establish the contribution of body mass index (BMI), sex, age, ethanol intake, hepatitis B (HBV) and hepatitis C (HCV) virus infection, coffee and drug consumption, and cigarette smoking to account for an elevated alanine transaminase (ALT) level in the general population. SUBJECTS: A total of 6315 adult subjects from the Dionysos study. METHODS: Logistic regression was used to quantify the contribution of the variables of interest to elevated ALT, defined as a value of ALT>60 U/l. Areas under ROC curves (AUCs) were calculated to assess accuracy. RESULTS: All the variables considered, with the exception of coffee and drug consumption, were significant predictors of elevated ALT at univariable analyses. When significant predictors were employed in a multivariable model, age and cigarette smoking were no longer significant. The AUC was 0.77 (95% CI=0.74-0.80) for the multivariable model and 0.64 (95% CI=0.60-0.68) for the univariable BMI model (p<0.0001 for the comparison). CONCLUSION: BMI is a good predictor of elevated ALT serum activity in the general population. The ability to predict an elevated ALT is however increased substantially by considering sex, ethanol intake, HBV and HCV infection together with BMI.

Cross-calibration of eight-polar bioelectrical impedance analysis versus dual-energy X-ray absorptiometry for the assessment of total and appendicular body composition in healthy subjects aged 21-82 years.

AIM: To calibrate eight-polar bioelectrical impedance analysis (BIA) against dual-energy X-ray absorptiometry (DXA) for the assessment of total and appendicular body composition in healthy adults. RESEARCH DESIGN: A cross-sectional study was carried out. SUBJECTS: Sixty-eight females and 42 males aged 21-82 years participated in the study. METHODS: Whole-body fat-free mass (FFM) and appendicular lean tissue mass (LTM) were measured by DXA; resistance (R) of arms, trunk and legs was measured by eight-polar BIA at frequencies of 5, 50, 250 and 500 kHz; whole-body resistance was calculated as the sum R of arms, trunk and legs. RESULTS: The resistance index (RI), i.e. the height(2)/resistance ratio, was the best predictor of FFM and appendicular LTM. As compared with weight (Wt), RI at 500 kHz explained 35% more variance of FFM (vs 0.57), 45% more variance of LTM(arm) (vs 0.48) and 36% more variance of LTM(leg) (vs 0.50) (p < 0.0001 for all). The contribution of age to the unexplained variance of FFM and appendicular LTM was nil or negligible and the RI x sex interactions were either not significant or not important on practical grounds. The percent root mean square error of the estimate was 6% for FFM and 8% for LTM(arm) and LTM(leg). CONCLUSION: Eight-polar BIA offers accurate estimates of total and appendicular body composition. The attractive hypothesis that eight-polar BIA is influenced minimally by age and sex should be tested on larger samples including younger individuals.

Sensitivity and specificity of body mass index and skinfold thicknesses in detecting excess adiposity in children aged 8-12 years.

PRIMARY OBJECTIVE: The study aimed to evaluate the sensitivity (SN) and specificity (SP) of body mass index (BMI) and skinfold thicknesses in detecting excess adiposity in children. RESEARCH DESIGN: Cross-sectional. MATERIALS AND METHODS: 986 children (500 females and 486 males) aged 10 +/- 1 years (mean +/- SD; range: 8-12 years) were studied. All underwent anthropometric measurements and bioelectrical impedance analysis (BIA). Dual-energy X-ray absorptiometry (DXA) was performed in 52 children to develop a population-specific algorithm for the assessment of fat-free mass (FFM) from BIA. The algorithm was applied to the remaining 934 children to estimate their FFM. Fat mass (FM) was obtained by subtracting FFM from weight (Wt). Values of FM:Wt were transformed in Z-scores and converted into 19 percentile categories (from 5 to 95 in steps of 5). The same procedure was performed with BMI and the log-transformed sum of four skinfold thicknesses (triceps, biceps, subscapular and suprailiac; lt-4SF). Excess adiposity was defined as a level of FM:Wt greater than the internally derived 85th percentile. SN and SP of each internally derived percentile of BMI and lt-4SF in detecting excess adiposity were calculated. RESULTS: In the pooled sample (n = 934), SN and SP were 0.39 and 0.99 for the 95th percentile of BMI, 0.65 and 0.95 for the 85th percentile of BMI, and 0.75 and 0.94 for the 85th percentile of lt-4SF. CONCLUSIONS: BMI percentiles employed in the present study have a high SP but a low SN in detecting excess adiposity in 8-12-year-old children. The use of the sum of four skinfolds has the potential to increase the SN of a screening programme for excess adiposity in children of this age.

Accuracy of an eight-point tactile-electrode impedance method in the assessment of total body water.

OBJECTIVE: To establish the accuracy of an eight-polar tactile-electrode impedance method in the assessment of total body water (TBW). DESIGN: Transversal study. SETTING: University department. SUBJECTS: Fifty healthy subjects (25 men and 25 women) with a mean (s.d.) age of 40 (12) y. METHODS: TBW measured by deuterium oxide dilution; resistance (R) of arms, trunk and legs measured at frequencies of 5, 50, 250 and 500 kHz with an eight-polar tactile-electrode impedance-meter (InBody 3.0, Biospace, Seoul, Korea). RESULTS: An algorithm for the prediction of TBW from the whole-body resistance index at 500 kHz (height (2)/R(500) where R is the sum of the segmental resistances of arms, trunk and legs) was developed in a randomly chosen subsample of 35 subjects. This algorithm had an adjusted coefficient of determination (r2(adj)) of 0.81 (P<0.0001) and a root mean square error (RMSE) of 3.6 l (9%). Cross-validation of the predictive algorithm in the remaining 15 subjects gave an r2(adj) of 0.87 (P<0.0001) and an RMSE of 3.0 l (8%). The precision of eight-polar BIA, determined by measuring R three times a day for five consecutive days in a fasting subject, was < or =2.8% for all segments and frequencies. CONCLUSION: Eight-polar BIA is a precise method that offers accurate estimates of TBW in healthy subjects. This promising method should undergo further studies of precision and its accuracy in assessing extracellular water and appendicular body composition should be determined. SPONSORSHIP: Modena and Reggio Emilia University.

Relationship between body composition and bone mineral content in young and elderly women.

PRIMARY OBJECTIVE: To study the relationship between bone mineral content (BMC), lean tissue mass (LTM) and fat mass (FM) in a large sample of young and elderly women. RESEARCH DESIGN: Cross-sectional. METHODS AND PROCEDURES: BMC, LTM and FM were measured by dual-energy X-ray absorptiometry in 2009 free-dwelling Caucasian women aged 63 +/- 7 years (mean +/- SD; range: 37-88 years). The majority of women were postmenopausal (96%). RESULTS: LTM explained 13% more variance of BMC than FM (R(2)(adj) = 0.39 vs 0.26, p < 0.0001) but weight (Wt) explained 5% more variance of BMC than LTM (R(2)(adj) = 0.44, p < 0.0001). The prediction of BMC obtained from LTM and FM (R(2)(adj)= 0.46, p < 0.0001) was only slightly better than that obtained from Wt. After the effects of age, Wt and height (Ht) on BMC were taken into account by multiple regression, the contribution of LTM and FM to BMC was just one-fifth of that of Wt (R(2)(adj) for full models < or =0.56, p < 0.0001). After a further correction for bone area (BA), the contribution of LTM and FM to BMC was just one-tenth of that of BA and not different from that of Wt and Ht on practical grounds (R(2)(adj) for full models = 0.84, p < 0.0001). Thus, after inter-individual differences in age, Wt, Ht (and bone size) are taken into account, the relationship between body composition and BMC is substantially weakened. CONCLUSIONS: In Caucasian women, (1) LTM is a stronger predictor of BMC than FM, but (2) Wt is a better predictor of BMC than body composition for practical purposes, and (3) Wt and body composition are not able to explain more than 46% of BMC variance.

Association of waist circumference and body mass index with fasting blood insulin in severely obese children: a cross-sectional study.

We tested whether body mass index (BMI) and waist circumference (WC) are associated with fasting insulin in severely obese children. A number of 391 (204 female and 187 male) obese children were consecutively enrolled in the study at a Paediatric outpatient clinic. They were aged 10+/-3 yr (mean+/-SD; range: 3-17 yr) and had a relative weight for age of 160+/-27% (mean+/-SD). BMI and WC explained respectively 9 and 13% of the variance of log-transformed (lt) insulin (p<0.0001 for both). After correction for age, however, BMI lost its association with lt-insulin (p=NS) and WC explained only 3% (p<0.001) of lt-insulin variance. Sex and pubertal status did not influence the relationship between WC, BMI and lt-insulin (p=NS, ANCOVA). We conclude that in severely obese children: 1) WC is a marginally better predictor of fasting blood insulin than BMI, 2) age has a substantial influence on the relationship between BMI, WC and insulin and, 3) the contribution of BMI and WC to insulin is of doubtful clinical relevance because it leaves a substantial portion (> or = 87%) of lt-insulin variance unexplained.

Assessment by bioimpedance of forearm cell mass: a new approach to calibration.

OBJECTIVE: Changes in skeletal muscle mass are involved in several important clinical disorders including sarcopenia and obesity. Unlike body fat, skeletal muscle is difficult to quantify in vivo, particularly without highly specialized equipment. The present study had a two-fold aim: to develop a regional (40)K counter for non-invasively estimating cell mass in the arm, mainly skeletal muscle cell mass, without radiation exposure; and to test the hypothesis that cell mass in the arm is highly correlated with electrical impedance after adjusting for the arm's length. METHODS: Forearm cell mass was estimated using a rectangular lead-shielded (40)K counter with 4-NaI crystals; impedance of the arm was measured at multiple frequencies using a segmental bioimpedance analysis (BIA) system. The system's within- and between-day coefficient of variation (CV) for (40)K-derived elemental potassium averaged 1.8+/-1.3 and 5.8+/-1.2%, respectively. The corresponding BIA system's CVs were 1.0+/-0.4 and 2.1+/-1.0%, respectively. SUBJECTS AND RESULTS: Participants in the study were 15 healthy adults (eight females, seven males; age 39+/-2.8 y, BMI 22.9+/-4.5 kg/m(2)). The right arm's K (5.2+/-1.7 g) was highly correlated with length-adjusted impedance (r(2)=0.81, 0.82, and 0.83 for 5, 50 and 300 kHz, respectively; all P<0.001); multiple regression analysis showed no additional improvement by adding age or sex to the prediction models. CONCLUSION: These results demonstrate the feasibility of calibrating BIA-measured electrical properties of the arm against estimates of arm cell mass, mainly of skeletal muscle, obtained by regional (40)K counting. This simple and practical approach should facilitate the development of BIA-based regional cell mass prediction formulas

Polysomnographic characterization of pergolide-induced sleep attacks in idiopathic PD.

Both dopamine agonists and levodopa may induce episodes termed "sleep attacks" in patients with PD. These episodes are well detailed behaviorally, but little is known about their neurophysiologic characterization. The authors performed a 24-hour polysomnography (PSG) in a PD patient taking pergolide in combination with levodopa, in which four of these diurnal sleep episodes occurred. PSG findings were followed up after pergolide withdrawal. Sleep episodes shared with narcolepsy both behavioral and EEG findings. However, pergolide partly restored a more physiologic sleep architecture, which was disrupted during therapy with levodopa alone.

Somatosensory processing during movement observation in humans.

OBJECTIVES: A neural system matching action observation and execution seems to operate in the human brain, but its possible role in processing sensory inputs reaching the cortex during movement observation is unknown. METHODS: We investigated somatosensory evoked potentials (SEPs), somatosensory evoked fields (SEFs) and the temporal spectral evolution of the brain rhythms (approximately 10 and approximately 20 Hz) following electrical stimulation of the right median nerve in 15 healthy subjects, during the following randomly intermingled conditions: a pure cognitive/attentive task (mental calculation); the observation of a motoric act (repetitive grasping) with low cognitive content ('Obs-grasp'); and the observation of a complex motoric act (finger movement sequence), that the subject had to recognize later on, therefore reflecting an adjunctive cognitive task ('Obs-seq'). These conditions were compared with an absence of tasks ('Relax') and actual motor performance. RESULTS: The post-stimulus rebound of the approximately 20 Hz beta magnetoencephalographic rhythm was reduced during movement observation, in spite of little changes in the approximately 10 Hz rhythm. Novel findings were: selective amplitude increase of the pre-central N(30) SEP component during both 'Obs-grasp' and 'Obs-seq', as opposed to the 'gating effect' (i.e. amplitude decrease of the N(30)) occurring during movement execution. The strength increase of the 30 ms SEF cortical source significantly correlated with the decrease of the approximately 20 Hz post-stimulus rebound, suggesting a similar pre-central origin. CONCLUSIONS: Changes took place regardless of either the complexity or the cognitive content of the observed movement, being related exclusively with the motoric content of the action. It is hypothesized that the frontal 'mirror neurons' system, known to directly facilitate motor output during observation of actions, may also modulate those somatosensory inputs which are directed to pre-central areas. These changes are evident even in the very first phases (i.e. few tens of milliseconds) of the sensory processing.

Some applications of indirect calorimetry to sports medicine.

Some applications of indirect calorimetry to sports medicine are discussed and exemplified by case reports. In particular, it is suggested that oxigen consumption can be employed to assess the effects of physical activity on fat-free tissues and that the respiratory quotient may offer some insights into the food habits of athletes.

Is body mass index a measure of adiposity in elderly women?

OBJECTIVE: To evaluate the accuracy of body mass index (BMI) as a predictor of body fat in elderly women. RESEARCH METHODS AND PROCEDURES: A total of 1423 women aged 67 +/- 5 (mean +/- SD, range: 60 to 88) years were consecutively enrolled into the study. Fat mass (FM) was measured using DXA. RESULTS: BMI explained 72.9% of FM variance (p < 0.0001), with a root mean square error of estimate (RMSE) of 3.5 kg. After standardization of RMSE on the dependent variable as RMSE%, the prediction error equaled 15%. BMI explained 54.8% of FM% variance (p < 0.0001), with an RMSE of 4.1%, corresponding to an RMSE% of 11%. DISCUSSION: The relatively high RMSE% of the FM and FM%-BMI associations caution against the use of BMI as an adiposity index in individual elderly women. However, an error corresponding to 11% of FM% may be accepted for population studies of body fat in elderly women.

Is fasting insulin associated with blood pressure in obese children?

PRIMARY OBJECTIVE: We tested whether fasting insulin levels are associated with blood pressure in a large sample of obese children. SUBJECTS AND METHODS: Three hundred and fifty obese children (F:M ratio = 1.03) of 10.1 +/- 2.7 y of age (mean +/- SD) were consecutively enrolled at an Outpatient Paediatric Clinic. Obesity was diagnosed on the basis of a relative weight for age > 120% and hypertension on the basis of a systolic (SBP) or diastolic (DBP) blood pressure > 95th percentile for age after adjustment for height (Ht). MAIN OUTCOME AND RESULTS: Insulin was significantly higher in hypertensive (n = 202, 58%) than normotensive (n = 148, 42%) children (16 vs 14 microU mL(-1), geometric mean, p < 0.01, ANOVA) but the difference was not clinically relevant. Moreover, (log-transformed) insulin explained only 7 and 4% of SBP and DBP variance, respectively (p < 0.0001 for both) and this contribution disappeared after the confounding effects of age, weight or other anthropometric dimensions were taken into account (p = ns, ANCOVA). CONCLUSIONS: This study does not support the hypothesis of a clinically relevant association between fasting insulin and blood pressure in obese children.

Changes of bioelectrical impedance after a body weight reduction program in highly obese subjects.

We used bioelectrical impedance analysis (BIA) as an exploratory tool to monitor the changes in body composition induced by a short-term (3-wk) weight reduction (energy-restricted diet, moderate aerobic exercise conditioning and psychological counselling) in 175 highly obese subjects (body mass index, BMI=41.7+/-5.8 kg/m2). The decrease in weight and BMI after the weight reduction program was 3.4% (geometric mean, p<0.0001) and 3.7+/-1.3 kg/m2 (mean+/-SD, p<0.0001), respectively. Bioelectrical impedance (Z) increased of about the same value at each of the measured frequencies (from 6+/-10% at 5 kHz to 5+/-9% at 100 kHz, mean+/-SD, p<0.0001). A statistically significant increase in Z5:Z100 was also seen (p<0.0001), but its clinical significance is questionable owing to its low absolute value (<1%). Taken together, these data suggest that no clinically relevant change in body water distribution occurred in our subjects as a result of the weight reduction program. However, the changes in Z did not satisfactorily predict the changes in anthropometric dimensions despite the evidence of a substantial association between Z and anthropometry both before and after the weight reduction program. Thus, accurate predictions of body composition changes in obese subjects may require more than two BIA measurements so as to have a better description of the weight-losing process.