Serial measurements of body composition in obese subjects during a very-low-energy diet (VLED) comparing bioelectrical impedance with hydrodensitometry

A Systematic Review and Meta-Analysis of the Effect of Caloric Restriction on Skeletal Muscle Mass in Individuals with, and without, Type 2 Diabetes

BACKGROUND

Severe caloric restriction interventions (such as very-low-calorie diets) are effective for inducing significant weight loss and remission of type 2 diabetes (T2DM). However, suggestions of associated significant muscle mass (MM) loss create apprehension regarding their widespread use. We conducted a systematic review and meta-analysis to provide a quantitative assessment of their effect on measures of MM in individuals with, or without, T2DM.

METHODS

EMBASE, Medline, Pubmed, CINAHL, CENTRAL and Google Scholar were systematically searched for studies involving caloric restriction interventions up to 900 kilocalories per day reporting any measure of MM, in addition to fat mass (FM) or body weight (BW).

RESULTS

Forty-nine studies were eligible for inclusion, involving 4785 participants. Individuals with T2DM experienced significant reductions in MM (WMD -2.88 kg, 95% CI: -3.54, -2.22; p < 0.0001), although this was significantly less than the reduction in FM (WMD -7.62 kg, 95% CI: -10.87, -4.37; p < 0.0001). A similar pattern was observed across studies involving individuals without T2DM. MM constituted approximately 25.5% of overall weight loss in individuals with T2DM, and 27.5% in individuals without T2DM. Subgroup analysis paradoxically revealed greater BW and FM reductions with less restrictive interventions.

CONCLUSIONS

Our review suggests that caloric restriction interventions up to 900 kilocalories per day are associated with a significant reduction in MM, albeit in the context of a significantly greater reduction in FM. Furthermore, MM constituted approximately a quarter of the total weight loss. Finally, our data support the use of less restrictive interventions, which appear to be more beneficial for BW and FM loss.

Impact of protein supplementation after bariatric surgery: A randomized controlled double-blind pilot study

OBJECTIVES

Bariatric patients are at risk of protein deficiency. The aim of this study was to determine possible benefits of postoperative protein supplementation weight reduction, body composition, and protein status.

METHODS

Twenty obese patients who underwent bariatric surgery were randomized either to the protein (PRO) group, which received a daily protein supplement over 6 months postoperatively, or to the control (CON) group, which received an isocaloric placebo in a double-blind fashion. Data on protein and energy intake, body weight, body composition, blood proteins, and grip force was collected preinterventionally and at 1, 3, and 6 months postoperatively.

RESULTS

In both groups body weight was significantly reduced to a similar extent (after 6 months: PRO group 25.4 ± 7.2%, CON group 20.9 ± 3.9%; intergroup comparison P > 0.05). Protein intake was steadily increased in the PRO group, but not in the CON group, and reached maximum at month 6 (25.4 ± 3.7% of energy intake versus 15.8 ± 4.4%; P < 0.001). In the PRO group, body fat mass loss was higher than that in the CON group (79% of absolute weight loss versus 73%; P = 0.02) while lean body mass loss was less pronounced (21% versus 27%, P = 0.05). Blood proteins and grip force did not differ at any time point between the two groups.

CONCLUSIONS

The present study suggests that protein supplementation after bariatric surgery improves body composition by enhancing loss of body fat mass and reducing loss of lean body mass within the 6 months follow up.

Feasibility of protein-sparing modified fast by tube (ProMoFasT) in obesity treatment: a phase II pilot trial on clinical safety and efficacy (appetite control, body composition, muscular strength, metabolic pattern, pulmonary function test)

Anecdotal data in the last few years suggest that protein-sparing modified diet (PSMF) delivered by naso-gastric tube enteral (with continuous feeding) could attain an significant weight loss and control of appetite oral feeding, but no phase II studies on safety and efficacy have been done up to now. To verify the safety and efficacy of a protein-sparing modified fast administered by naso-gastric tube (ProMoFasT) for 10 days followed by 20 days of a low-calorie diet, in patients with morbid obesity (appetite control, fat free mass maintenance, pulmonary function tests and metabolic pattern, side effects), 26 patients with a BMI ≥30 kg/m2 have been selected. The patients had to follow a protein-sparing fast by enteral nutrition (ProMoFasT) for 24 h/day, for 10 days followed by 20 days of low-calorie diet (LCD). The endpoint was represented by body weight, BMI, abdominal circumference, Haber's appetite test, body composition by body impedance assessment (BIA), handgrip strength test, metabolic pattern, pulmonary function test. Safety was assessed by evaluation of complications and side effects of PSMF and/or enteral nutrition. In this report the results on safety and efficacy are described after 10 and 30 days of treatment. After the recruiting phase, a total of 22 patients out of 26 enrolled [14 (63.6 %) females] were evaluated in this study. Globally almost all clinical parameters changed significantly during first 10 days. Total body weight significantly decreased after 10 days (∆-6.1 ± 2; p < 0.001) and this decrease is maintained in the following 20 days of LCD (∆ = -5.88 ± 1.79; p < 0.001). Also the abdominal circumference significantly decreased after 10 days [median (range): -4.5 (-30 to 0); p < 0.001] maintained then in the following 20 days of LCD [median (range) = -7 (-23.5 to -2); p < 0.001]. All BIA parameters significantly changed after 10 and 30 days from baseline. All parameters except BF had a significant change after 10 days of treatment while the difference at 30 days was lower than at 10 days for TBW, FFM and MM with no significant differences from baseline for the last two characteristics. For VAS appetite the difference was significant after 10 days and the decrease in appetite was maintained at 30 days with no significant difference (p = 0.83) between 10 and 30 days. No significant differences in the first 30 days were detected for PA and for both left and right hand grip strength. Particularly, a significant reduction of 1.82 kg in FFM after 10 days was detected, but not after 30 days. In contrast, a decrease of 3.8 kg of BF is observed after 30 days. As far as the respiratory functional tests (RFT) are concerned, a significant difference at 10 days was globally observed for functional residual capacity (p = 0.012) and expiratory reserve volume (p = 0.025). There are no reported major complications and side effects resulting from the enteral nutrition or PSMF. In particular, cardiac arrhythmias have not been reported. From the clinical point of view the PSMF with naso-gastric tube (ProMoFasT) method appears safe, it is associated with a significant weight loss related to decrease of FM and not to loss of FFM and appetite decreases. It is relevant that the RFT are significantly improved after only 10 days suggesting the efficacy of this regime in short period, too. These preliminary data underline the necessity to increase the number of RCT for this method, which could represent a possible alternative to other methodologies, such as the intragastric balloon, in particular when it is recommended to improve RFT before bariatric, gynecological, orthopedic and lymphatic surgery.

Comparison of Methods to Assess Body Composition Changes during a Period of Weight Loss

OBJECTIVE

To assess the accuracy of body composition measurements by air displacement plethysmography and bioelectrical impedance analysis (BIA) compared with DXA during weight loss.

RESEARCH METHODS AND PROCEDURES

Fifty-six healthy but overweight participants, 34 women and 22 men (age, 52 +/- 8.6 years; weight, 92.2 +/- 11.6 kg; BMI, 33.3 +/- 2.9 kg/m(2)) were studied in an outpatient setting before and after 6 months of weight loss (weight loss, 5.6 +/- 5.5 kg). Subjects were excluded if they had initiated a new drug therapy within 30 days of randomization, were in a weight loss program, or took a weight loss drug within 90 days of randomization. Subjects were randomly assigned either to a self-help program, consisting of two 20-minute sessions with a nutritionist and provision of printed materials and other self-help resources, or to attendance at meetings of a commercial program (Weight Watchers). Body composition was examined by each of the methods before and after weight loss.

RESULTS

BIA (42.4 +/- 5.8%) underestimated percentage fat, whereas the BodPod (Siri = 51.7 +/- 6.9%; Brozek = 48.5 +/- 6.5%) overestimated percentage fat compared with DXA (46.1 +/- 7.9%) before weight loss. Correlation coefficients for detecting changes in body composition between DXA and the other methods were relatively high, with Brozek Deltafat mass (FM; r(2) = 0.63), Siri FM (r(2) = 0.65), tetrapolar BIA percentage fat (r(2) = 0.57), and Tanita FM (r(2) = 0.61) being the highest.

DISCUSSION

In conclusion, all of the methods were relatively accurate for assessing body composition compared with DXA, although there were biases. Furthermore, each of the methods was sensitive enough to detect changes with weight loss.

Usefulness of different techniques for measuring body composition changes during weight loss in overweight and obese women

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

Good agreement between bioelectrical impedance and dual-energy X-ray absorptiometry for estimating changes in body composition during weight loss in overweight young women

AIMS

To compare estimations of body composition using two different methods of bioelectrical impedance analysis (BIA) with dual X-ray absorptiometry (DXA) for estimating body composition during weight loss in overweight and obese young females.

METHODS

Twenty-four overweight or obese females (age 29.5+/-6.1 years, BMI 36.4+/-4.3 kg/m(2)) had body composition assessed using single-frequency (Tanita Ultimate Scale; SF-BIA) and multi-frequency (Impedimed SFB7; MF-BIA) BIA and DXA before and after a 10-week weight loss intervention.

RESULTS

MF-BIA estimates of body composition showed good absolute agreement with DXA, as evidenced by the small biases in the estimation of fat free mass (FFM), fat mass (FM) and percentage body fat (BF%); however, the limits of agreement for each variable were wide (bias +/-1.96 standard deviation; FFM -1.6+/-6.5 kg, FM 1.6+/-6.5 kg, BF% 1.4+/-6.3%). SF-BIA exhibited a larger bias with wide limits of agreement (FFM 3.8+/-9.1 kg, FM -3.8+/-9.1 kg, BF% -4.37+/-10.3%). During weight loss the values provided by MF-BIA and SF-BIA were not significantly different from DXA (p> or =0.89) due to small bias and the limits of agreement were narrow (MF-BIA: FFM -0.01+/-3.74 kg, FM 0.01+/-3.74 kg, BF% 0.22+/-3.40%; SF-BIA: FFM 0.40+/-3.92 kg, FM -0.40+/-3.92 kg, BF% 0.25+/-3.40%).

CONCLUSION

Compared with DXA, both the MF-BIA and SF-BIA accurately assessed changes in body composition with weight loss but, compared with SF-BIA, MF-BIA provided superior cross-sectional estimates of body composition.

What is the required energy deficit per unit weight loss?

One of the most pervasive weight loss rules is that a cumulative energy deficit of 3500 kcal is required per pound of body weight loss, or equivalently 32.2 MJ kg(-1). Under what conditions is it appropriate to use this rule of thumb and what are the factors that determine the cumulative energy deficit required per unit weight loss? Here, I examine this question using a modification of the classic Forbes equation that predicts the composition of weight loss as a function of the initial body fat and magnitude of weight loss. The resulting model predicts that a larger cumulative energy deficit is required per unit weight loss for people with greater initial body fat-a prediction supported by published weight loss data from obese and lean subjects. This may also explain why men can lose more weight than women for a given energy deficit since women typically have more body fat than men of similar body weight. Furthermore, additional weight loss is predicted to be associated with a lower average cumulative energy deficit since a greater proportion of the weight loss is predicted to result from loss of lean body mass, which has a relatively low energy density in comparison with body fat. The rule of thumb approximately matches the predicted energy density of lost weight in obese subjects with an initial body fat above 30 kg but overestimates the cumulative energy deficit required per unit weight loss for people with lower initial body fat. International Journal of Obesity (2008) 32, 573-576; doi:10.1038/sj.ijo.0803720; published online 11 September 2007.

Assessment of body composition change in a community-based weight management program

OBJECTIVE

The purpose of this study was to validate the use of the leg-to-leg bioelectrical impedance analysis (BIA) system in assessing change in body composition over 32 weeks in overweight and obese women participating in a community weight management program.

DESIGN

Intervention, with subjects prescribed an energy-restriction diet and exercise program for 32 weeks and body composition measured pre-study and after 12 and 32 weeks.

SUBJECTS AND SETTING

Overweight and obese premenopausal women (n=201) with no overt disease were recruited at six sites into community-based weight loss programs. One hundred and twenty-four women completed all aspects of the study.

INTERVENTION

Energy intake was set at 0.8 x resting metabolic rate (RMR) for weeks 1 through 12, 1.0 x RMR for weeks 13 through 20 and 1.2 x RMR for weeks 21 through 32. Energy intake was based on a food exchange table, with the number of food exchanges adjusted to encourage a percent distribution of 55% carbohydrate, 30% fat and 15% protein. Subjects increased their daily walking distance by 3.2 km above pre-study levels.

MEASURES OF OUTCOME

Underwater weighing, seven skinfolds, and leg-to-leg BIA tests were used to assess body composition.

RESULTS

A 3 x 3 repeated measures ANOVA revealed no significant difference in detecting change in FFM at 12 and 32 weeks among underwater weighing, BIA and skinfold, (F(4,492)=1.73, p=0.141) (decrease in FFM of 1.0+/-3.3 kg, 1.7+/-2.2 kg, and 1.4+/-3.3 kg respectively, 32 weeks).

CONCLUSIONS

The leg-to-leg BIA system provides a valid measure of body composition change in overweight premenopausal women during a 32-week community-based weight loss program.

The influence of weight loss on fibrinolytic and metabolic parameters in obese children and adolescents

We studied i) whether short-term weight loss alters plasminogen activator inhibitor-1 antigen (PAI-1-Ag) and tissue-type plasminogen activator antigen (tPA-Ag) in obese children, and ii) whether changes in body composition and/or abdominal adiposity are responsible for changes in PAI-1 and tPA-Ag. 20 obese boys (mean age 11.9 yr) and 40 obese girls (mean age 12 yr) were studied before and after three weeks of low-caloric diet and physical activity. Body composition was assessed by means of bioelectrical impedance, and the waist-to-hip ratio (WHR) was measured. Blood samples were determined for insulin, glucose, triglycerides, PAI-1-Ag, tPA-Ag, and the fasting insulin resistance index (FIRI) was calculated. Boys had a greater WHR, higher levels of glucose, and a slightly greater FIRI than girls. Estimates of adiposity, insulin, and triglycerides were correlated with PAI-1 and tPA-Ag. WHR was significantly correlated with fibrinolytic parameters only in girls. Insulin and tPA-Ag contributed to PAI-1 (adj. R2 = 0.36, p <0.0001), whereas percentage fat mass and triglycerides contributed to tPA-Ag (adj. R2 = 0.469, p <0.0001). The weight loss program significantly reduced adiposity, abdominal adiposity, and lowered fibrinolytic and metabolic parameters. Initial levels of PAI-1 and changes in body mass contributed to the fall in PAI-1 (adj. R2 = 0.18, p = 0.0016) and initial levels of tPA-Ag contributed significantly to changes in tPA-Ag (adj. R2 = 0.57, p <0.0001). The results suggest that changes in fibrinolytic parameters are associated with the loss in body mass but can occur independently of a concomitant reduction in fatness. Although initial PAI-1 and tPA-Ag predict the changes of these fibrinolytic parameters, the results do not exclude the possibility that the improvement in metabolic state and changes in unmeasured parameters related to physical activity and low-caloric diet could have influenced our findings.

Validating a practical approach to determine weight control in obese children and adolescents

OBJECTIVE

To study the usefulness of a mathematical index for assessing changes in body composition of obese children and adolescents who undergo a weight control program.

DESIGN

A short-term longitudinal (mean of 19 months) cohort study.

SUBJECTS

Sixty-seven obese children and adolescents (38 M, 29 F, age 6-16 (mean 11)y) who took part in a clinic-based weight control program.

MEASUREMENTS

Percentage body fat was assessed at the start of the program by underwater weighing (UWW) and by bioelectrical impedance (BIA). Response to the program was assessed by a mathematical index (MI), based on observed and expected changes in height and weight, and by changes in percentage fat as measured by BIA.

RESULTS

Adiposity, as assessed by BIA at the start of the program, was highly correlated to that obtained by UWW (r = 0.96 for fat-free mass). Changes in the MI over the program were correlated fairly well (r = -0.81, SEE = 3.57 kg) with changes in percentage fat as assessed by BIA.

CONCLUSION

Using change in BIA as criterion, the MI is valid for assessing changes in percentage body fat of obese children and adolescents over time. This index is of use to clinicians who lack body composition equipment and need a quick method to analyze the effectiveness of a weight control program in obese children and adolescents.

Relationship between different subcutaneous adipose tissue layers, fat mass, and leptin in response to short-term energy restriction in obese girls

This study addresses whether the expected relationship of 15 specified subcutaneous adipose tissue layers (SAT layers) from 1-neck to 15-calf and body fat mass (FM) with leptin was influenced by a weight-loss program. In 30 obese girls (10 prepubertal, 15 pubertal, and 5 late/postpubertal) SAT layers were measured by means of the optical device Lipometer. Fat mass (FM) was estimated indirectly by means of bioelectrical impedance. Leptin and insulin were determined by means of radioimmunoassays. All measurements were performed before (pre) and after (post) 3 weeks of low-caloric diet and physical training. At the beginning of the study, there were significant correlations for all estimates of adiposity and leptin (0.67 to 0.79; P < 0.0001). Five SAT layers from the upper body and the trunk (0.48 to 0.67; P < 0.01) but none from the abdominal region and lower extremities were correlated with leptin. FM together with SAT layers 4-upper back and 8-lower abdomen (negative slope) explained 79% of the variation in pre leptin values (P < 0.0001). The weight-loss program significantly reduced leptin (P < 0.0001), insulin (P = 0.04), estimates of adiposity (P < 0.0001), and SAT layers 4-upper back (P = 0.0006), 11-front thigh, 13-rear thigh, and 14-inner thigh (P between <0.03 and <0.01). Although significant, the reductions in the four SAT layers were small. Estimated fat-free mass was significantly increased after three weeks (P < 0.05). Changes in SAT layers from the upper extremities and from the trunk were inversely correlated to the decrease in leptin (P between <0.05 and <0.001). Initial leptin was the best correlate of the decrease in leptin (adj. R(2) = 0.815; P < 0.0001). However, when only changes in adiposity and insulin were considered in the regression model, changes in insulin contributed to the fall in leptin (adj. R(2) = 0.23; P = 0.004). When changes in SAT layers were added to the model, changes in SAT layers 2-triceps and 10-hip (negative slopes) contributed to the decrease in leptin (adj. R(2) = 0.48; P < 0.0001). After weight loss, correlations between estimates of post adiposity and post leptin (0.40, P = 0.01 to 0.57, P = 0.0005) were lower compared with pre values. SAT layers 4-upper back and 3-biceps contributed independently to post leptin values (adj. R(2) = 0.50; P < 0.0001). It is suggested that fat mass and SAT layers from the upper body are the main determinants of leptin in obese girls before weight loss. The diet and sports intervention program reduced leptin independent of the reduction in adiposity. The distribution of subcutaneous fat might be a stable correlate of circulating leptin after a short-term reduction in energy intake. Am. J. Hum. Biol. 12:803-813, 2000. Copyright 2000 Wiley-Liss, Inc.

Daily hunger sensation and body compartments: II. Their relationships in obese patients

Hunger sensation (HS) is a signal whose levels change during the 24-h day. The daily mean level of HS was correlated with the human body compartments, as investigated by bioelectrical impedance analysis, to detect the relationship between the orectic perception and both the free fat mass (FFM) and the fat body mass (FBM) in 22 clinically healthy subjects (CHS) (2 M, 20 W, BMI: 18.5-24.0 kg/m2) and 48 obese patients (OP) (4 M, 44 W, BMI: 25.2-54.7 kg/m2). In CHS, the daily mean level of HS correlated positively with the FFM and negatively with the FBM. These correlations were not present in OP. This lack of relationships between HS and the body compartments where energy is maximally consumed (i.e., the FFM) and maximally stored (i.e., the FBM) indicates that the orectic response to energy expenditure and the orectic inhibition to fat accumulation are feedback mechanisms which are impaired in obesity.

Use of the leg-to-leg bioelectrical impedance method in assessing body-composition change in obese women

BACKGROUND

There is little information on whether bioelectrical impedance analysis (BIA) accurately predicts changes in body composition associated with energy restriction, exercise, or both.

OBJECTIVE

We had 2 objectives: to determine the validity of the leg-to-leg BIA system in 1) estimating body composition in obese and nonobese women, with a cross-sectional design, and 2) assessing changes in body composition in obese women in response to 12 wk of energy restriction, exercise training, or both.

DESIGN

Subjects were 98 moderately obese women (43.2 +/- 0.6% body fat, 45.0 +/- 1.1 y of age) and 27 nonobese control subjects (24.0 +/- 1.5% body fat, 43.5 +/- 2.5 y of age). Obese subjects were randomly divided into 1 of 4 groups, with fat-free mass, fat mass, and percentage body fat estimated with BIA and underwater weighing before and after 12 wk of intervention. The 4 groups were diet only (4.19-5.44 MJ/d), exercise only (five, 45-min sessions/wk at 78.5 +/- 0.5% of maximum heart rate), both exercise and diet, and control (no diet or exercise).

RESULTS

No significant difference was found between underwater weighing and BIA in estimating the fat-free mass of the obese and nonobese women (all subjects combined, r = 0.78, P < 0.001, SEE = 3.7 kg) or in estimating decreases in fat mass during 12 wk of energy restriction, exercise, or both in obese subjects (F[3.85] = 1.45, P = 0.233).

CONCLUSIONS

The leg-to-leg BIA system accurately assessed fat-free mass in obese and nonobese women, and changes in fat mass with diet alone or when combined with exercise.