Bioelectrical impedance vs. four-compartment model to assess body fat change in overweight adults

Impact of weight loss and weight gain trajectories on body composition in a population at high risk of type 2 diabetes: A prospective cohort analysis

AIM

In a primary care population at high risk of type 2 diabetes, 24-month weight change trajectories were used to investigate the impact of weight cycling on fat mass (FM) and fat-free mass (FFM).

MATERIALS AND METHODS

Cohort data from the Walking Away from Type 2 Diabetes trial was used, which recruited adults at-risk of type 2 diabetes from primary care in 2009/10. Annual weight change trajectories based on weight loss/gain of ≥5% were assessed over two 24-month periods. Body composition was measured by bioelectrical impedance analysis. Repeated measures were analysed using generalized estimating equations with participants contributing up to two 24-month observation periods.

RESULTS

In total, 622 participants were included (average age = 63.6 years, body mass index = 32.0 kg/m2 , 35.4% women), contributing 1163 observations. Most observations (69.2%) were from those that maintained their body weight, with no change to FM or FFM. A minority (4.6% of observations) lost over 5% of body weight between baseline and 12 months, which was then regained between 12 and 24 months. These individuals regained FM to baseline levels, but lost 1.50 (0.66, 2.35) kg FFM, adjusted for confounders. In contrast, those that gained weight between baseline and 12 months but lost weight between 12 and 24 months (5.5% of observations) had a net gain in FM of 1.70 (0.27, 3.12) kg with no change to FFM.

CONCLUSION

Weight cycling may be associated with a progressive loss in FFM and/or gain in FM in those with overweight and obesity at-risk of type 2 diabetes.

Using open source accelerometer analysis to assess physical activity and sedentary behaviour in overweight and obese adults

Background

Physical activity and sedentary behaviour are difficult to assess in overweight and obese adults. However, the use of open-source, raw accelerometer data analysis could overcome this. This study compared raw accelerometer and questionnaire-assessed moderate-to-vigorous physical activity (MVPA), walking and sedentary behaviour in normal, overweight and obese adults, and determined the effect of using different methods to categorise overweight and obesity, namely body mass index (BMI), bioelectrical impedance analysis (BIA) and waist-to-hip ratio (WHR).

Methods

One hundred twenty adults, aged 24–60 years, wore a raw, tri-axial accelerometer (Actigraph GT3X+), for 3 days and completed a physical activity questionnaire (IPAQ-S). We used open-source accelerometer analyses to estimate MVPA, walking and sedentary behaviour from a single raw accelerometer signal. Accelerometer and questionnaire-assessed measures were compared in normal, overweight and obese adults categorised using BMI, BIA and WHR.

Results

Relationships between accelerometer and questionnaire-assessed MVPA (Rs = 0.30 to 0.48) and walking (Rs = 0.43 to 0.58) were stronger in normal and overweight groups whilst sedentary behaviour were modest (Rs = 0.22 to 0.38) in normal, overweight and obese groups. The use of WHR resulted in stronger agreement between the questionnaire and accelerometer than BMI and BIA. Finally, accelerometer data showed stronger associations with BMI, BIA and WHR (Rs = 0.40 to 0.77) than questionnaire data (Rs = 0.24 to 0.37).

Conclusions

Open-source, raw accelerometer data analysis can be used to estimate MVPA, walking and sedentary behaviour from a single acceleration signal in normal, overweight and obese adults. Our data supports the use of WHR to categorise overweight and obese adults. This evidence helps researchers obtain more accurate measures of physical activity and sedentary behaviour in overweight and obese populations.

Relative abdominal adiposity is associated with chronic low back pain: a preliminary explorative study

Background

Although previous research suggests a relationship between chronic low back pain (cLBP) and adiposity, this relationship is poorly understood. No research has explored the relationship between abdominal-specific subcutaneous and visceral adiposity with pain and disability in cLBP individuals. The aim of this study therefore was to examine the relationship of regional and total body adiposity to pain and disability in cLBP individuals.

Methods

A preliminary explorative study design of seventy (n = 70) adult men and women with cLBP was employed. Anthropometric and adiposity measures were collected, including body mass index, waist-to-hip ratio, total body adiposity and specific ultrasound-based abdominal adiposity measurements. Self-reported pain and disability were measured using a Visual Analogue Scale (VAS) and the Oswestry Disability Index (ODI) questionnaires respectively. Relationships between anthropometric and adiposity measures with pain and disability were assessed using correlation and regression analyses.

Results

Significant correlations between abdominal to lumbar adiposity ratio (A-L) variables and the waist-to-hip ratio with self-reported pain were observed. A-L variables were found to predict pain, with 9.1–30.5 % of the variance in pain across the three analysis models explained by these variables. No relationships between anthropometric or adiposity variables to self-reported disability were identified.

Conclusions

The findings of this study indicated that regional distribution of adiposity via the A-L is associated with cLBP, providing a rationale for future research on adiposity and cLBP.

Relationship between body fat and BMI in a US hispanic population-based cohort study: Results from HCHS/SOL

OBJECTIVE

To evaluate the percentage of body fat (%BF)-BMI relationship, identify %BF levels corresponding to adult BMI cut points, and examine %BF-BMI agreement in a diverse Hispanic/Latino population.

METHODS

%BF by bioelectrical impedance analysis was corrected against %BF by (18) O dilution in 434 participants of the ancillary Hispanic Community Health Study/Study of Latinos. Corrected %BF was regressed against 1/BMI in the parent study (n = 15,261), fitting models for each age group, by sex, and Hispanic/Latino background; predicted %BF was then computed for each BMI cut point.

RESULTS

Bioelectrical impedance analysis underestimated %BF by 8.7 ± 0.3% in women and 4.6 ± 0.3% in men (P < 0.0001). The %BF-BMI relationship was nonlinear and linear for 1/BMI. Sex- and age-specific regression parameters between %BF and 1/BMI were consistent across Hispanic/Latino backgrounds (P > 0.05). The precision of the %BF-1/BMI association weakened with increasing age in men but not women. The proportion of participants classified as nonobese by BMI but as having obesity by %BF was generally higher among women and older adults (16.4% in women vs. 12.0% in men aged 50-74 years).

CONCLUSIONS

%BF was linearly related to 1/BMI with consistent relationship across Hispanic/Latino backgrounds. BMI cut points consistently underestimated the proportion of Hispanics/Latinos with excess adiposity.

Intraclass Correlation Coefficients for Obesity Indicators and Energy Balance-Related Behaviors Among New York City Public Elementary Schools

OBJECTIVE

Sample size and statistical power calculation should consider clustering effects when schools are the unit of randomization in intervention studies. The objective of the current study was to investigate how student outcomes are clustered within schools in an obesity prevention trial.

METHOD

Baseline data from the Food, Health & Choices project were used. Participants were 9- to 13-year-old students enrolled in 20 New York City public schools (n= 1,387). Body mass index (BMI) was calculated based on measures of height and weight, and body fat percentage was measured with a Tanita® body composition analyzer (Model SC-331s). Energy balance-related behaviors were self-reported with a frequency questionnaire. To examine the cluster effects, intraclass correlation coefficients (ICCs) were calculated as school variance over total variance for outcome variables. School-level covariates, percentage students eligible for free and reduced-price lunch, percentage Black or Hispanic, and English language learners were added in the model to examine ICC changes.

RESULTS

The ICCs for obesity indicators are: .026 for BMI-percentile, .031 for BMIz-score, .035 for percentage of overweight students, .037 for body fat percentage, and .041 for absolute BMI. The ICC range for the six energy balance-related behaviors are .008 to .044 for fruit and vegetables, .013 to .055 for physical activity, .031 to .052 for recreational screen time, .013 to .091 for sweetened beverages, .033 to .121 for processed packaged snacks, and .020 to .083 for fast food. When school-level covariates were included in the model, ICC changes varied from -95% to 85%.

CONCLUSIONS

This is the first study reporting ICCs for obesity-related anthropometric and behavioral outcomes among New York City public schools. The results of the study may aid sample size estimation for future school-based cluster randomized controlled trials in similar urban setting and population. Additionally, identifying school-level covariates that can reduce cluster effects is important when analyzing data.

Epicardial adipose tissue relating to anthropometrics, metabolic derangements and fatty liver disease independently contributes to serum high-sensitivity C-reactive protein beyond body fat composition: a study validated with computed tomography

BACKGROUND

Epicardial adipose tissue (EAT) measured by echocardiography has been proposed to be associated with metabolic syndrome and increased cardiovascular risks. However, its independent association with fatty liver disease and systemic inflammation beyond clinical variables and body fat remains less well known.

METHODS

The relationships between EAT and various factors of metabolic derangement were retrospectively examined in consecutive 359 asymptomatic subjects (mean age, 51.6 years; 31% women) who participated in a cardiovascular health survey. Echocardiography-derived regional EAT thickness from parasternal long-axis and short-axis views was quantified. A subset of data from 178 randomly chosen participants were validated using 16-slice multidetector computed tomography. Body fat composition was evaluated using bioelectrical impedance from foot-to-foot measurements.

RESULTS

Increased EAT was associated with increased waist circumference, body weight, and body mass index (all P values for trend = .005). Graded increases in serum fasting glucose, insulin resistance, and alanine transaminase levels were observed across higher EAT tertiles as well as a graded decrease of high-density lipoprotein (all P values for trend <.05). The areas under the receiver operating characteristic curves for identifying metabolic syndrome and fatty liver disease were 0.8 and 0.77, with odds ratio estimated at 3.65 and 2.63, respectively. In a multivariate model, EAT remained independently associated with higher high-sensitivity C-reactive protein and fatty liver disease.

CONCLUSIONS

These data suggested that echocardiography-based epicardial fat measurement can be clinically feasible and was related to several metabolic abnormalities and independently associated fatty liver disease. In addition, EAT amount may contribute to systemic inflammation beyond traditional cardiovascular risks and body fat composition.

Body composition determination by bioimpedance: an update

PURPOSE OF REVIEW

To review various methods for measuring body composition by bioimpedance and their limitations, as well as available impedance meters, including body fat analyzers for home use.

RECENT FINDINGS

Bioimpedance spectroscopy, which requires multifrequency impedance meters, is preferable for fluid volume measurements, especially extracellular fluid, whereas bioimpedance analysis at 50 kHz is more widely used for measuring fat-free mass. A method for using bioimpedance spectroscopy equations with 50 kHz impedance meters has been recently proposed and successfully tested. Low cost foot-to-foot impedance meters (body fat analyzers) with plantar electrodes on a body scale, that are easy and fast to use, have been compared with medical impedance meters and with dual X-ray absorptiometry measurements and found reasonably accurate, except for individuals with very low or high BMI.

SUMMARY

Body composition by bioimpedance is gaining acceptance in nutrition, hemodialysis, gerontology and sports medicine. Body fat analyzers that have been validated by comparison with dual x-ray absorptiometry could be useful to general practitioners, nutritionists and cardiologists.

Field methods in the evaluation of obesity in children and adolescents

In large samples, the methods for obtaining information on obesity need to be simple, inexpensive and reasonably accurate. This review deals with articles focusing on various field methods for the evaluation of body composition. The Bioimpedance and Near Infrared methods are simple to execute but their advantage in relation to Body Mass Index is obscure. Although the Bioimpedance and near infrared methods provide estimates of fat content, they may be no better than waist circumference measurements. The latter does not distinguish body fat but points to a more direct relationship concerning health risk. Regardless of the advantages, waist circumference continues to be under discussion: there is a lack of standardization and no reference populations or cutoff points have been established. No perfect method exists, but the number of errors could be reduced, if care were taken in drawing up protocols, standardization, and the analysis of sample properties.

Metabolic parameters after BioEnterics Intragastric Balloon placement in obese patients

BACKGROUND

BioEnterics Intragastric Balloon (BIB) is a non-invasive, temporary and relatively safe procedure shown to be effective in the short-term treatment of obesity. Nowadays, BIB does not show convincing evidence of significant long-term weight loss, as compared with conventional management, and data regarding changes in metabolic and nutritional parameters are lacking.

METHODS

Forty obese patients [11 males, 29 females, age 36.65+/-10.6 yr, body mass index (BMI) 44.9+/-8.9 kg/m2] were evaluated before and 3 and 6 months after BIB placement by assessment of anthropometric and biochemical parameters as well as nutritional habits.

RESULTS

Patients showed a significant reduction in weight (-13.2+/-6.5%), BMI (-13.2%), waist circumference (-6.5 cm), and percentage of fat mass (-19.5%), but not fat-free mass. A significant improvement in insulin sensitivity but not in lipid pattern was seen. After BIB insertion, a significant reduction in caloric intake was paralleled by a redistribution of nutrients; in particular, increased lipid (12.8%) and decreased carbohydrate (-11.7%) percentage, but not absolute intake was observed.

CONCLUSION

These data show that BIB improves anthropometric parameters, with reduction of fat mass and preservation of fat-free mass, as well as insulin resistance, but not other metabolic features. The observed change in dietary habits, with a relative increase in lipid intake, once BIB is removed, might favor body weight regain and impact negatively on body weight composition and the other traits of the metabolic syndrome.

Mechanisms behind GLP-1 induced weight loss

Endogenous glucagon-like peptide-1 (GLP-1) is an incretin hormone that plays an important role in maintaining pancreatic function as well as caloric intake. Since the advent of GLP-1 receptor agonists resistant to dipeptidyl peptidase-4 (DPP-4) (degradation, it has become clear that their chronic use promotes negative energy balance. With regard to their effects on body weight, the principal action of GLP-1 agonists is mediated via their inhibition of eating. In searching for the underlying mechanism of GLP-1 receptor agonist-induced anorexic effect, scientists have discovered pathways in the central nervous system, as well as in the periphery. This review describes emerging knowledge of a peripheral endocrine GLP-1 system mediating its activity through a central ascending GLP-1 pathway and targeting hypothalamic sites involved in the regulation of energy homeostasis. Thus peripheral and central GLP-1 sensitive pathways appear to be organised to co-operatively help control food intake and body weight.Br J Diabetes Vasc Dis 2008;8 (Suppl 2): S34—S41

Anti-obesity drugs

BACKGROUND

Recent discoveries about the metabolic and genetic control systems that govern regulation of body weight and energy expenditure have afforded the opportunity to develop pharmacological agents that can be used as adjunctive treatments for patients with obesity. However, the scarcity of medications available or those that have made it to Phase III trials reflects the difficult challenge of manipulating the biology of appetite regulation.

OBJECTIVE

The aim of this study was to inform health professionals about new anti-obesity medications that target neuronal systems within the central nervous system and peripheral humoral proteins that send signals to the central nervous system.

METHODS

A critical review was conducted of information available from the medical literature.

RESULTS/CONCLUSIONS

An emerging theme is to use combination therapies that are directed towards several targets or leverage existing gastrointestinal satiety hormonal signals. By using combination therapies, it is anticipated that greater weight loss will be achieved compared to monotherapy.