Single frequency bioelectrical impedance is a poor method for determining fat mass in moderately obese women

Assessment of Changes in Body Composition During the First Postoperative Year After Bariatric Surgery

BACKGROUND

The potential effect of bariatric surgery on weight reduction and improvement of associated comorbidities is known, but the ratio obtained between the components of body weight, including lean body mass, body fat mass, and bone mass, is still not determined. This study aims to verify the changes in body composition during the first year after bariatric surgery.

METHODS

We conducted a prospective observational cohort study. Fifty patients who underwent bariatric surgery and maintained follow-ups were selected. Patients were assessed preoperatively and postoperatively for periods of 1, 3, 6, and 12 months using tetrapolar bioelectrical impedance analysis and laboratory testing of lipids and serum albumin levels. Data were statistically analyzed.

RESULTS

Statistically significant differences (p < 0.001) were obtained between the preoperative and 12-month evaluation respectively, for body mass index (BMI) (45.8 ± 7.5 to 30.0 ± 4.8 kg/m²), FM (64.7 ± 15.5 to 30.6 ± 9.8 kg), PFM (51.6 ± 4.17 to 37.3 ± 7.6%), and total cholesterol levels (197.1 ± 49.8 to 169.8 ± 31.0 mg/dL). The decrease in PFM shows a better proportion between the body components. PFM showed significantly higher decrease in males than in females (p = 0.012). Lean body mass (p = 0.000) reduction was highest for patients operated by the Unified Health System (SUS, Government of Brazil) probably because of its few financial resources to maintain postoperative care.

CONCLUSION

The change in body composition of patients who underwent Roux-en-Y gastric bypass was statistically significant for all variables examined during the first year postoperatively. This shows the effectiveness of the surgical procedure and clinical protocol set, which tends to favor a better health prognosis and weight maintenance in the long term.

Cold-Activated Brown Adipose Tissue is Associated with Less Cardiometabolic Dysfunction in Young Adults with Obesity

OBJECTIVE

This study aimed to test the hypothesis that young adults with obesity and cold-activated brown adipose tissue (BAT) are less likely to have metabolic dysfunction (dyslipidemia, insulin resistance, and hypertension) than those without cold-activated BAT. Previous studies have noted a potentially protective effect of BAT and higher adiponectin/leptin ratios, but they have acknowledged that the clinical implications of these findings remain uncertain.

METHODS

Twenty-one females and twenty-three males with obesity (BMI ≥ 30 kg/m² ) underwent a 2-hour cooling protocol before ¹⁸ F-fluorodeoxyglucose (¹⁸ F-FDG)-positron emission tomography/x-ray computed tomography scan to determine the prevalence, volume, and ¹⁸ F-FDG uptake of cold-activated BAT.

RESULTS

Cold-activated BAT was identified in 43% of participants (11 female, 8 male); females had greater ¹⁸ F-FDG uptake. Those with cold-activated BAT had a lesser degree of metabolic dysfunction. Cold-activated BAT volume correlated with triglycerides (inversely) and adiponectin (concordantly). Body-mass-adjusted cold-activated BAT activity correlated with high-density lipoprotein cholesterol (concordantly). Males with cold-activated BAT had lower leptin and higher adiponectin/leptin ratio.

CONCLUSIONS

A high prevalence of cold-activated BAT was found in the study participants. BAT could be important in decreasing metabolic dysfunction among young adults with obesity, making it a potential target for treating metabolically unhealthy obesity.

Leg to leg bioelectrical impedance analysis of percentage fat mass in obese patients-Can it tell us more than we already know?

BACKGROUND

Bioelectrical impedance analysis (BIA) is well tolerated, inexpensive, and readily available, but can it be used to detect with clinical precision aberrant changes in the proportion of fat mass to fat-free mass during weight loss?

OBJECTIVES

To assess the variance in percentage body fat mass explained by the readily available inputs and assess residual variance provided by leg-to-leg BIA scales.

METHODS

Using cross-sectional data from a cohort of 665 patients of Indian ethnicity presenting for bariatric surgery, we examine the determinants of percentage body fat as provided by leg-to-leg output from Tanita SC-330 BIA scales.

RESULTS

Four input factors-sex, weight, height, and age-contributed to provide 92% and 95% explanation in output variance for percentage fat mass (%FM) and actual fat mass, respectively, in 665 patients. Body mass index alone explained 89% and 81% of variance in %FM output for women and men, respectively. Neither weight distribution, as indicated by waist and hip circumference or waist to hip ratio, nor plasma lipids or markers of glucose metabolism contributed additional variance in %FM when controlled for the 4 key inputs.

CONCLUSIONS

Simple, known input variables dominate the leg-to-leg BIA output of %FM, and this may compromise the detection of aberrant changes in %FM and fat-free mass with substantial weight loss. For clinical research, validated methods not largely dependent on known inputs should be used for evaluating changes in body composition after substantial weight loss.

Comprehensive assessment of physical functioning in bariatric surgery candidates compared with subjects without obesity

BACKGROUND

Obesity appears to be associated with reduced physical performance, but comprehensive assessments of physical functioning are lacking in subjects with severe obesity, in particular in comparison with subjects without obesity. This precludes an objective assessment of the degree of impairment.

OBJECTIVE

To compare motor skills and cardiopulmonary fitness between subjects with severe obesity (OB) (i.e., candidates for bariatric surgery) and control subjects without obesity (non-OB).

SETTING

Cantonal Hospital, Switzerland.

METHODS

Flexibility, movement speed, balance, maximal isometric strength, and cardiopulmonary fitness were tested in 45 OB (body mass index: 42.6±.9 kg/m(2); age: 35±1.7 years; 33 women) and 32 non-OB (body mass index: 23±.4 kg/m(2); age: 38.5±2.1 years; 25 women) subjects.

RESULTS

In comparison with the non-OB group, the OB group showed reduced shoulder flexibility (P<.001) but comparable hamstrings flexibility (P = .3). Speed-related tasks (i.e., timed up-and-go test and timed lying-to-standing test) indicated that the OB group was slower than the non-OB group (all P<.007). Strength-related tasks indicated a greater absolute back muscle and knee-extensor strength (all P<.002) in the OB group with no difference in knee-flexor strength (both P>.8). However, when related to weight, the OB group showed reduced maximal strength (all P<.002). Bicycle spiroergometry indicated that absolute oxygen consumption at peak exercise and at the anaerobic threshold did not differ between groups (both P>.06). Related to weight, however, values were lower in the OB than in the non-OB group (both P< .001).

CONCLUSION

Data indicate a differential pattern of functional impairment in bariatric surgery candidates compared with subjects without obesity. These findings might help to establish tailored intervention protocols to improve physical performance in such subjects.

Subcutaneous and segmental fat loss with and without supportive supplements in conjunction with a low-calorie high protein diet in healthy women

BACKGROUND

Weight loss benefits of multi-ingredient supplements in conjunction with a low-calorie, high-protein diet in young women are unknown. Therefore, the purpose of this study was to investigate the effects of a three-week low-calorie diet with and without supplementation on body composition.

METHODS

Thirty-seven recreationally-trained women (n = 37; age = 27.1 ± 4.2; height = 165.1 ± 6.4; weight = 68.5 ± 10.1; BMI = 25.1 ± 3.4) completed one of the following three-week interventions: no change in diet (CON); a high-protein, low-calorie diet supplemented with a thermogenic, conjugated linoleic acid (CLA), a protein gel, and a multi-vitamin (SUP); or the high-protein diet with isocaloric placebo supplements (PLA). Before and after the three-week intervention, body weight, %Fat via dual X-ray absorptiometry (DXA), segmental fat mass via DXA, %Fat via skinfolds, and skinfold thicknesses at seven sites were measured.

RESULTS

SUP and PLA significantly decreased body weight (SUP: PRE, 70.47 ± 8.01 kg to POST, 67.51 ± 8.10 kg; PLA: PRE, 67.88 ± 12.28 kg vs. POST, 66.38 ± 11.94 kg; p ≤ 0.05) with a greater (p ≤ 0.05) decrease in SUP than PLA or CON. SUP and PLA significantly decreased %Fat according to DXA (SUP: PRE, 34.98 ± 7.05% to POST, 32.99 ± 6.89%; PLA: PRE, 34.22 ± 6.36% vs. POST, 32.69 ± 5.84%; p ≤ 0.05), whereas only SUP significantly decreased %Fat according to skinfolds (SUP: PRE, 27.40 ± 4.09% to POST, 24.08 ± 4.31%; p ≤ 0.05). SUP significantly (p ≤ 0.05) decreased thicknesses at five skinfolds (chest, waist, hip, subscapular, and tricep) compared to PLA, but not at two skinfolds (axilla and thigh).

CONCLUSIONS

The addition of a thermogenic, CLA, protein, and a multi-vitamin to a three-week low-calorie diet improved weight loss, total fat loss and subcutaneous fat loss, compared to diet alone.

Review article: The nutritional and pharmacological consequences of obesity surgery

BACKGROUND

Obesity surgery is acknowledged as a highly effective therapy for morbidly obese patients. Beneficial short-term effects on common comorbidities are practically undisputed, but a growing data pool from long-term follow-up reveals increasing evidence of potentially severe nutritional and pharmacological consequences.

AIMS

To assess the prevalence, causes and symptoms of complications after obesity surgery, to elucidate and compare therapy recommendations for macro- and micronutrient deficiencies, and to explore surgically-induced effects on drug absorption and bioavailability, discussing ramifications for long-term therapy and prophylaxis.

METHODS

PubMed, Embase and MEDLINE were searched using terms including, but not limited to, bariatric surgery, gastric bypass, obesity surgery and Roux-en-Y, coupled with secondary search terms, e.g. anaemia, micronutrients, vitamin deficiency, bacterial overgrowth, drug absorption, pharmacokinetics, undernutrition. All studies in English, French or German published January 1980 through March 2014 were included.

RESULTS

Macro- and micronutrient deficiencies are common after obesity surgery. The most critical, depending on surgical technique, are hypoalbuminemia (3-18%) and deficiencies of vitamins B1 (≤49%), B12 (19-35%) and D (25-73%), iron (17-45%) and zinc (12-91%). Many drugs commonly administered to obese patients (e.g. anti-depressants, anti-microbials, metformin) are subject to post-operative and/or PPI-associated changes affecting bioavailability and absorption.

CONCLUSIONS

Complications are associated with pre-operative and/or post-operative malnutrition or procedure-related changes in intake, absorption and drug bioavailability. The high prevalence of nutrient deficiencies after obesity surgery makes life-long nutritional monitoring and supplementation essential. Post-operative changes to drug absorption and bioavailability in bariatric patients cast doubt on the validity of standard drug dosage and administration recommendations.

Correction factors for the calculation of metabolic equivalents (MET) in overweight to extremely obese subjects

BACKGROUND/OBJECTIVES

The metabolic equivalent (MET) is a construct that is commonly used to quantify physical activity as well as exercise performance. 'One MET' is equal to a resting oxygen uptake of 3.5 ml O2 kg(-1) min(-)(1). However, this assumption is unlikely valid in obese subjects. The aim of our study was to quantify the difference between calculated and measured METs in overweight to severely obese subjects and to provide body mass index (BMI)-specific MET correction factors.

SUBJECTS/METHODS

Resting oxygen uptake (VO2-REE) was measured in 1331 patients with a BMI >25 kg m(-2) (72.0% women; age: 42.5 ± 13.0 years; BMI: 42.5 ± 7.0 kg m(-)(2)) by indirect calorimetry and MET-REE, that is, VO2-REE related to body weight was calculated. Six hundred and fifty-two subjects (70.9% women) additionally underwent a bicycle cardiopulmonary exercise test for measurement of maximal MET (MET peak).

RESULTS

Mean MET-REE was 2.47 ± 0.33 ml O2 kg(-1) min(-1) in women and 2.62 ± 0.34 ml O2 kg(-1) min(-1) in men, that is, markedly lower than the expected 3.5 ml O2 kg(-1) min(-1). MET-REE decreased with increasing BMI (P<0.001 for both sexes). On this dataset, gender-specific MET correction factors were developed for distinct BMI groups. During the exercise test, women performed 4.4 ± 1.3 MET peak and men 4.7 ± 1.3. After applying our correction factors, MET peak increased to 6.2 ± 1.7 and 6.1 ± 1.6, respectively.

CONCLUSIONS

Data indicate that the commonly used 1-MET value of 3.5 ml O2 kg(-)(1) min(-)(1) largely overestimates values in overweight to severely obese subjects. Our correction factors can help to reduce this systematic error and thus appear to be valuable for clinical practice as well as research studies.

The effects of exercise training in addition to energy restriction on functional capacities and body composition in obese adults during weight loss: a systematic review

BACKGROUND

Obesity is associated with impairments of physical function, cardiovascular fitness, muscle strength and the capacity to perform activities of daily living. This review examines the specific effects of exercise training in relation to body composition and physical function demonstrated by changes in cardiovascular fitness, and muscle strength when obese adults undergo energy restriction.

METHODS

Electronic databases were searched for randomised controlled trials comparing energy restriction plus exercise training to energy restriction alone. Studies published to May 2013 were included if they used multi-component methods for analysing body composition and assessed measures of fitness in obese adults.

RESULTS

Fourteen RCTs met the inclusion criteria. Heterogeneity of study characteristics prevented meta-analysis. Energy restriction plus exercise training was more effective than energy restriction alone for improving cardiovascular fitness, muscle strength, and increasing fat mass loss and preserving lean body mass, depending on the type of exercise training.

CONCLUSION

Adding exercise training to energy restriction for obese middle-aged and older individuals results in favourable changes to fitness and body composition. Whilst weight loss should be encouraged for obese individuals, exercise training should be included in lifestyle interventions as it offers additional benefits.

Comparison of DEXA-derived body fat measurement to two race-specific bioelectrical impedance equations in healthy Indians

AIM

Prevalence of obesity is increasing in Asian Indians. Reliable, precise and convenient methods to estimate body composition are required. This study aimed to test the accuracy of bioelectrical impedance analysis (BIA) estimates of body composition among Asian Indians according to two BIA equations--one developed for Asians, the other for Caucasians.

METHODS

Two hundred apparently healthy Asian Indians (100 males, 100 females; mean age 36.6 ± 7.6 years; mean BMI 16.6-46.7 kg/m(2)) underwent BIA assessment of fat mass (FM), fat free mass (FFM) and percentage body fat (%BF) using Tanita Multi-Frequency Body Composition Analyzer MC-180MA (Tanita Corporation, Tokyo, Japan). One set of BIA values was automatically calculated by the analyzer (Caucasian figures), the other set by Tanita (Japanese Asian figures). Results were compared to dual X-ray absorptiometry (DEXA) as the standard measure.

RESULTS

A moderate level of relative agreement was found between the DEXA-derived measurement of %BF and the estimate from both the Caucasian (r(2)=0.75; p<0.001) and Asian equation (r(2)=0.7; p<0.001). Despite this, the level of absolute agreement was poor, with large bias and wide limits of agreement. According to the Caucasian equation the mean difference between methods was -8.3 ± 3.9 (95% limits of agreement -20.10 to 9.40), for the Asian equations mean difference was -5.4 ± 4.3 (95% limits of agreement -20.63 to 11.41).

INTERPRETATION AND CONCLUSIONS

When compared to DEXA, the current Asian and Caucasian Tanita formulae significantly under-estimate the %BF of Asian Indians.

Prediction of whole-body and segmental body composition by bioelectrical impedance in morbidly obese subjects

BACKGROUND

Validated equations for body composition analysis using bioelectrical impedance (BIA) in morbidly obese (MO) subjects are scarce. Thus, our aim was todevelop new equations from physical and BIA parameters to estimate whole-body and segmental body composition inMO subjects, with dual-energy X-ray absorptiometry(DXA) as the reference method.

METHODS

A cross-sectional study on 159 Caucasian MO subjects (female 78%, age 43.5 ± 11.8 years, BMI 45.6 ± 4.9 kg/m2) divided in two groups was conducted: model building cohort (n = 110) and model validation cohort (n 0 49). Stepwise regression analysis was used to develop specific fat free mass (FFM) and fat mass (FM) equations.

RESULTS

Gender, body weight, and height2/impedance accounted, respectively, for 89.4% (p < 0.001) and 89.3% (p < 0.001) of the variability of DXA-total FFM in the two cohorts. Using the new equation, the mean difference between the DXA-FFM and BIA-FFM estimates was +0.180 kg (95% CI: -0.34 to +0.7 kg, p 0 NS), and the resulting limits of agreement were +6.76 and −6.40 kg. Similarly, good estimates of DXA truncal-, android-, and gynoid-FM from anthropometric and BIA parameters could be obtained from weight, height2/impedance, and waist and hip circumferences (respectively, R2 adjusted: 0.657, 0.776, and 0.770; p < 0.001).

CONCLUSIONS

The new equations derived from physical and BIA parameters provide accurate estimates of body composition in MO subjects.

Assessment tools in obesity - psychological measures, diet, activity, and body composition

The global increase in the prevalence of obesity has led to an increased need for measurement tools for research, management and treatment of the obese person. The physical size limitations imposed by obesity, variations in body composition from that of normal weight, and a complex psychopathology all pose tremendous challenges to the assessment of an obese person. There is little published research regarding what tools can be used with confidence. This review is designed to provide researchers and clinicians with a guide to the current and emerging measurement tools specifically associated with obesity research and practice. Section 1 addresses psychological measures of well being. Sections 2, 3, and 4 focus on the assessment of food intake, activity, and body composition. All sections address basic challenges involved in the study and management of obesity, and highlight methodological issues associated with the use of common assessment tools. The best available methods for use in the obese both in research and clinical practice are recommended.

Poor prediction of resting energy expenditure in obese women by established equations

The objective of the study was to evaluate the accuracy of established prediction equations that calculate resting energy expenditure (REE) in obese women. This was a cross-sectional study. In 273 mildly to severely obese women (age, 41.7 +/- 13.2 years; body mass index, 42.8 +/- 7.0 kg/m(2)), REE was measured by indirect calorimetry (mREE), along with fat mass (FM) and fat-free mass (FFM) by bioelectrical impedance analysis. Eleven established equations were used to predict REE (pREE), with 9 equations basing on the anthropometric parameters body weight and height and 2 equations including body composition parameters (FM, FFM). All equations provided pREE values that significantly correlated with mREE (r > 0.66, P < .001), although 8 equations systematically underestimated mREE (P < .05). Of note, even the best equation was not able to accurately predict mREE with a deviation of less than +/-10% in more than 70% of the tested women. Furthermore, equations using body composition data were not superior in predicting REE as compared with equations exclusively including anthropometric variables. Multiple linear regression analyses revealed 2 new equations--one including body weight and age and another including FM, FFM, and age--that explained 56.9% and 57.2%, respectively, of variance in mREE. However, when these 2 new equations were applied to an independent sample of 33 obese women, they also provided an accurate prediction (+/-10%) of mREE in only 56.7% and 60.6%, respectively, of the women. Data show that an accurate prediction of REE is not feasible using established equations in obese women. Equations that include body composition parameters as assessed by bioelectrical impedance analysis do not increase the accuracy of prediction. Based on our results, we conclude that calculating REE by standard prediction equations does not represent a reliable alternative to indirect calorimetry for the assessment of REE in obese women.