Abstract
Background
Several studies have shown that liquid and food intake interfere with the evaluation of body composition in adults. However, since there are no reports about this interference in the elderly population, the need to fast for this evaluation may be dispensable.
Objectives
The objective of the present study was to assess the influence of liquid and solid food on the measurement of body composition by bioelectrical impedance analysis (BIA) and by dual energy X-ray absorptiometry (DXA).
Design
Forty-one male volunteers aged 62 to 87 years participated in the study. The subjects were submitted to evaluation of body composition by DXA and BIA under fasting conditions and 1 hour after the ingestion of breakfast (500 ml of orange juice and one 50 g bread roll with butter).
Results
There was no significant difference in the variables fat-free mass (FFM) or fat mass (FM) between the fasting condition and the evaluation performed 1 hour after the meal as measured by BIA or DXA. There was also no significant difference when the same variables were compared between methods.
Conclusion
In the present study, the ingestion of 500 ml orange juice and of one bread roll with butter by elderly subjects did not affect the results of the parameters of body composition determined by BIA or DXA. Thus, these exams could be performed without the rigor of fasting, often poorly tolerated by the elderly.
Key words: Body composition, bioelectrical impedance, dual-energy X-ray absorptiometry, meal ingestion, hydration, elderly
Introduction
One of the changes occurring with aging is related to body composition, with the observation of a relative increase in body fat, a reduction in lean body mass, as well as modifications in the amount of minerals in the lean mass and in the proportion between intra- and extracellular water (1). In this process, the increase in adipose tissue follows a typical pattern that delineates a centripetal distribution, with a special increase in visceral fat, while the extremities lose lean mass, fat and bone mass (2).
Other changes are also part of the aging process, such as reduced taste, olfact and visual acuity, and cognitive, psychological and social alteration, which usually provoke inadequate food ingestion, consequently leading to weight loss. Taken together, weight loss and modification of body composition are associated with micronutrient deficiency, fragility, increased number of hospital admissions, increased risk of falls due to functional incapacity, and ultimately with premature death. In addition, the aged population, even healthy, has difficulty in recovering lost weight, during a relatively long follow-up period (6 months), (3).
Thus, the evaluation of body composition is an important part of clinical assessment of older persons and different methods have been applied with this aim.
The methods most frequently used for the evaluation of body composition establish a quantitative relation between fat mass (FM) and fat-free mass (FFM) according to a bicompartmental model. Among them, bioelectrical impedance analysis (BΙA) is extensively used in clinical practice because of its reproducibility and easy application (4). It is a noninvasive low-cost method that permits a rapid and precise analysis (5). Previous studies have shown that this technique is reliable for use in the aged, but with the need to use specific equations for this population (6, 7). This technique is usually precise in healthy individuals, but its results are impaired in obese subjects and in individuals with edema and chronic renal failure (8).
Other method, dual-energy X-ray absorptiometry (DXA), is being extensively used for the determination of body composition. It is a noninvasive and safe method that requires a short time for application, involving a low radiation dose (<0.1 μGy) and permitting the estimate not only of whole body composition, but also of the various body segments (9). DXA permits the evaluation of the three body compartments with high precision and accuracy (10) properties that have led it to be considered the gold standard for the measurement of body composition (11) and as the reference method for the standardization of measurements obtained with other techniques.
It is recommended in clinical practice that BΙA be performed after about 8 hours of fasting due to the possible influence of food on the measurement of body composition (12). However, few studied have evaluated the effect of food on the body composition of adults and, to the best of our knowledge, studies about this topic in the elderly are scarce (13). Since in this age range prolonged fasting is often poorly tolerated and may lead to deficient calorie intake on that day, it is especially relevant to clarify this aspect in view of the importance of a reliable determination of this measurement, especially in the elderly. Thus, the objective of the present study was to assess the effect of liquid and solid food ingestion on the measurement of body composition by BΙA and DXA in elderly subjects.
Methods
Studied Population
Forty-one male volunteers aged 62 to 87 years participated in the study. Inclusion criteria were age of more than 60 years and not being unable to walk or to perform the exams proposed. Severely debilitated and obese elderly subjects, subjects with decompensated kidney and liver disease, bedridden patients, patients with a heart pacemaker, using an orthopedic prosthesis, patients with osteosynthesis or presenting advanced demential syndromes, edema and ascites were excluded. The study was approved by the Research Ethics Committee of the University Hospital, Faculty of Medicine of Ribeirão Preto, University of São Paulo, and all subjects gave written informed consent to participate.
Experimental Design and Methods
The study model was cross-sectional. The evaluations were performed in the morning after a 12 hour fast and immediately after micturition. Weight was determined and the DXA exam was performed, followed by BΙA. A standardized meal was then offered, consisting of one 50 g bread roll with 6 g of margarine and 500 ml of orange juice (298,5 kcal, 71,8% of energy from carbohydrate, 8,58% of energy from protein and 19,61% of energy from lipid).
The subjects were instructed to eat the complete meal offered. After one hour they were asked to empty their bladder again and the same exams were repeated.
Body Composition
Body composition was determined by whole body DXA (Hologic, QDR 4500W, Waltham, MA, USA). The coefficient of variation of DXA detected in the present group was 0.39% for body weight, 1.83% for lean mass and 6.48% for fat mass. The coefficient of variation was estimated by the method suggested by Gluer et al. (14).
Body composition was also assessed by BΙA (BΙA 101, Q-RJL Systems, Detroit, MI, USA). The subjects were instructed to empty their bladder before the analyses and to remain in the supine position 10 minutes before the evaluation in a climatically controlled room with a temperature ranging from 24 °C to 26 °C. During the analysis the subjects kept their limbs in abduction (12). The equation of Roubenoff et al. (15), specifically developed for use in the elderly, was employed to estimate FFM by BΙA.
Statistical Analysis
Data are reported as mean and standard deviation and were analyzed using the Sotware R (version 2.6.2). Data obtained before and after the ingestion of breakfast were analyzed by the paired t-test with the level of significance set at 5% (16).
Results
The characteristics of the elderly subjects who participated in the study are described in Table 1 as range and mean ± SD.
Table 1.
Characteristics of the Elderly Subjects Evaluated, Reported as Means ± Standard Deviation
| Variable (N=41) | Range | Mean ± SD |
|---|---|---|
| Age (years) | 62-91 | 74.78±6.48 |
| Height (m) | 1.56-1.75 | 1.65±0.04 |
| Weight (Kg) | 42-84 | 60.3±11.99 |
| BMI (Kg/m2) |
16-30 |
22.08±4.07 |
N, number of volunteers.
Analysis of weight (60.3±12.0 and 60.5±12.0 Kg), FFM DXA (46.2±6.7 and 46.5±6.8 Kg), FFM BΙA (46.8±5.3 and 47.0±5.1 Kg), FM DXA (13.3±6.2 and 13.4±6.0 Kg), and FM BΙA (13.5±7.5 and 13.5±7.7 Kg), before and after the meal, respectively, revealed that there was no difference, showing that the consumption of this amount of food did not affect the evaluation of these data. When FFM obtained by BΙA before (46.8±5.3) and after (47.0±5.1) the meal was compared to the results obtained by DXA before (46.2±6.7) and after (46.5±6.8) the meal, there was no statistically significant differences and when FM obtained by BΙA before (13.5±7.5) and after (13.5±7.7) the meal was compared to that obtained by DXA before (13.3±6.2) and after (13.4±6.0) the meal, again no statistically significant differences were observed.
Aditionally, when the differences of the results obtained for each patient before and after the meal were analyzed, the variation rate was small (table 2), with small significant differences observed only in weight and BMI, as expected following a meal.
Table 2.
Characteristics of the Volunteers Regarding Weight, BMI, Resistance, Reactance and Body Composition Determined by DXA (Kg) and BΙA (Kg) Before and After a Meal, Reported as Mean±Standard Deviation
| Before the meal | After the meal | Mean differences | Percent differences | |
|---|---|---|---|---|
| Weight (Kg) | 60.3 ±12.0 | 60.5±12.0 | 0.26±0.11* | 0.45±0 |
| BMI (Kg/m2) | 22.08±4.08 | 22.18±4.06 | 0.09±0.04* | 0.45±0 |
| Resistance () | 545±96 | 540±89 | -5.15±8.76 | -0.71±3 |
| Reactance () | 50.87±11 | 51.75±12 | 0.87±7.35 | 2.02±14 |
| FFM DXA (Kg) | 46.2±6.7 | 46.5±6.8 | 0.26±1.14 | 0.56±2 |
| FFM BΙA (Kg) | 46.8±5.3 | 47.0±5.1 | -0.23±0.88 | 0.57±2 |
| FM DXA (Kg) | 13.3±6.2 | 13.4±6.0 | 0.04±1.30 | 1.32±10 |
| FM BΙA (Kg) |
13.5±7.5 |
13.5±7.7 |
0.05±1.30 |
-0.04±11 |
*p<.05, paired t-test; BMI, body mass index;, ohms; FFM DXA, Fat-free mass assessed by DXA; FFM BΙA, Fat-free m assessed by BΙA; FM DXA, Fat mass assessed by DXA; FM BΙA, Fat mass assessed by BΙA.
Discussion
The changes in body composition of the elderly are associated with the effects of aging itself and with the various disorders that may arise with aging. However, there are no literature data about several physiological factors that may influence the determination of body composition by BΙA, the method more frequently used in clinical practice for the measurement of lean and fat mass. In the present study we observed that a mixed meal containing solid and liquid food did not interfere with the results obtained by BΙA in elderly subjects.
In the present study, DXA was used as the reference standard in relation to BΙA due to its precision in the analysis of body composition. The calculation of body fat by DXA has been previously validated (17), who demonstrated a strong correlation between the fat content measured by DXA and by computed tomography (CT). Thus, this technique is being widely used in studies on the elderly in order to estimate quantitatively the three major components of body composition, i.e., bone, fat and lean mass (18). The equipment used in the present study was previously used by Visser et al. (1999), who observed a good correlation (r2=0.98) between FFM measurements obtained by DXA and CT in the elderly (19).
In the present study we used the BΙA equation of Roubenoff et al. (15) which has been specifically validated for the elderly. That study (15) observed a strong correlation between the body composition measurements obtained by the same techniques as used in the present study. The use of specific equations for this age range has been recommended, since these equations are based on the changes in body composition that occur physiologically in the elderly.
In the present study, the body composition of the subjects was assessed under fasting conditions and one hour after the consumption of breakfast, with no significant difference being detected between the two measurements, demonstrating that it is not necessary to recommend fasting to this population. Small significant differences were observed in weight and BMI, but they were clinically insignificant and expected after a meal; other differences were random and non-significant. These findings are in contrast to the recommendations made by Kyle et al. (12), who emphasized that, for adults, the consumption of food and drink 2 to 4 hours before the evaluation of body composition by BΙA may lead to an error in the estimate of body compartments, with rigorous fasting thus being recommended for at least 8 hours before the exam.
Another study similar to the present one, (13) evaluated by DXA the influence of hydration and food ingestion on the body composition of healthy young people under fasting conditions and one hour after the ingestion of breakfast, lunch and dinner. The authors did not detect changes in the data evaluated (body weight, fat mass and lean mass) after breakfast, when the subjects ingested 400 ml of liquid, but did detect an increase in lean mass in the trunk region when the subjects ingested a liquid amount of more than 2400 ml. Thus, their study indicated that there may be an interference of liquid ingestion with the measurement of lean mass by DXA, but only when an unusually large amount of liquid is ingested.
Regarding BΙA, previous studies have suggested little influence of feeding on the results. In this respect, Rallison et al. (20) stated that the abdominal cavity is considered to be an electrically silent area, so that the visceral content formed by food and by the gastric, biliary, pancreatic and intestinal secretions released as an effect of the feeding stimulus do not influence the measurement of body composition. Probably the low influence of feeding on the analysis of body composition by BΙA is due to the low body resistance generated by the trunk region compared to other regions of the body. The upper and lower limbs, where the electrodes are attached, are the major contributors to body resistance, with rates of 28% and 33%, respectively. Some studies have pointed out that the trunk generates only 9% of the resistance for total body impedance (21).
Another hypothesis that may be raised regarding the present results is that the BΙA technique used here may have not been sufficiently sensitive to detect changes in the body compartments after a small meal. The bioelectric impedance instrument used in our study produces a monofrequential electrical current of 50 kHz and does not cross the cell membrane, so that it does not run along intercellular spaces (8, 22).
As was the case for the measurement of FM, there was also a strong correlation between the measurements of FFM by BΙA and DXA, as also observed by Bolanowski and Nilsson, (23) who evaluated 100 volunteers aged 16 to 78 years. Similarly, Sun et al., (24) detected a good correlation in fat percent between DXA and BΙA in 591 healthy volunteers aged 19 to 60 years.
In the present study, an attempt was made to reduce errors in the analysis of body composition by BΙA by performing the exams with rigorous standardization of subject positioning, room temperature, time of day, placement of the electrodes, and always after bladder emptying. Thus, the chance of technical errors was significantly reduced.
BΙA produced statistically similar results compared to DXA, suggesting a strong association between the two methods of analysis and representing a more economic, more practical and easier method for the assessment of nutritional status.
The present results indicate that the ingestion of a small meal (up to 500 ml of liquid) did not affect the measurement of body composition of elderly subjects by BΙA and DXA one hour after consumption. This finding permits the execution of these exams for the evaluation of body composition without the rigor of fasting, which is often poorly tolerated by the elderly. Further studies are needed considering larger amounts of food and different time intervals after ingestion.
Financial disclosure: Karla Vilaça: During the research was supported by a scholarship Grant from Coordenação de Aperfeiçoamento de Pessoal de Nível Superior -CAPES. The institution did not interfere in the research design, development or results. Eduardo Ferriolli: no support or other form of conflicts of interest. Nereida Κ. da Costa Lima: no support or other form of conflicts of interest. Francisco Jose A. Paula: no support or other form of conflicts of interest. Julio C. Moriguti: no support or other form of conflicts of interest.
Author contributions: Karla Vilaça: research design, data collection, data analysis, article writing. Eduardo Ferriolli: data analysis, article writing and revision. Nereida Κ. da Costa Lima: data analysis, article revision. Francisco Jose A. Paula: data collection, data analysis, article revision. Julio C. Moriguti: research design, data collection, data analysis, article writing and revision.
Financial disclosure: None of the authors had any financial interest or support for this paper.
References
- 1.Fontana L., Klein S. Aging, Adiposity, and Calorie Restriction. JAMA. 2007;297:986–994. doi: 10.1001/jama.297.9.986. 10.1001/jama.297.9.986 PubMed PMID: 17341713. [DOI] [PubMed] [Google Scholar]
- 2.Kyle U.G., Genton L., Lukaski H.C., Dupertuis Y.M., Slosman D.O., Hans D., Pichard C. Comparison of fat-free mass and body fat in Swiss and American adults. Nutrition. 2005;21:161–169. doi: 10.1016/j.nut.2004.04.023. 10.1016/j.nut.2004.04.023 PubMed PMID: 15723744. [DOI] [PubMed] [Google Scholar]
- 3.Moriguti J.C., Das S.K., Saltzman E., Corrales A., McCrory M.A., Greenberg A.S., Roberts S. Effects of a 6-week hypocaloric diet on changes in body composition, hunger and subsequent weight regain in healthy young and older adults. J. Gerontol. 2000;55A:B580–B587. doi: 10.1093/gerona/55.12.b580. [DOI] [PubMed] [Google Scholar]
- 4.Ravaglia G., Forti P., Maioli F., Boschi F., Cicognani A., Gasbarrini G. Measurement of body fat in healthy elderly men: a comparison of methods. J. Gerontol. A. Biol. Sci. Med. Sci. 1999;54(2):M70–M76. doi: 10.1093/gerona/54.2.m70. PubMed PMID: 10051858. [DOI] [PubMed] [Google Scholar]
- 5.Buffa R., Floris G., Marini E. Migration of the bioelectrical impedance vector in healthy elderly subjects. Nutrition. 2003;19:917–921. doi: 10.1016/s0899-9007(03)00180-1. 10.1016/S0899-9007(03)00180-1 PubMed PMID: 14624938. [DOI] [PubMed] [Google Scholar]
- 6.Dey D.K., Bosacus I. Comparison of bioelectrical impedance prediction equations for fat-free mass in a population-based sample of 75 y olds: the NORA study. Nutrition. 2003;19:858–864. doi: 10.1016/s0899-9007(03)00172-2. 10.1016/S0899-9007(03)00172-2 PubMed PMID: 14559321. [DOI] [PubMed] [Google Scholar]
- 7.Valencia M.E., Alemán-Mateo H., Salazar G., Triana M.H. Body composition by hydrometry (deuterium oxide dilution) and bioelectrical impedance in subjects aged > 60 y from rural regions of Cuba, Chile and Mexico. Int. J. Obesity. 2003;27:848–855. doi: 10.1038/sj.ijo.0802315. 10.1038/sj.ijo.0802315 [DOI] [PubMed] [Google Scholar]
- 8.Kyle U.G., Bosaeus I., De Lorenzo A.D., Deurenberg P., Elia M., Gómez J.M., Heitmann B.L., Kent-Smith L., Melchior J.C., Pirlich M., Scharfetter H., Schols A.M.W.J., Pichard C. Composition of the ESPEN Working Group. Bioelectrical impedance analysis — part I: review of principles and methods. Clin. Nutr. 2004;23:1226–1243. doi: 10.1016/j.clnu.2004.06.004. 10.1016/j.clnu.2004.06.004 PubMed PMID: 15380917. [DOI] [PubMed] [Google Scholar]
- 9.Mazess R.B., Barden H.S., Bisek J.P., Hanson J. Dual-energy x-ray absorptiometry for total body and regional bone-mineral and soft-tissue composition. Am. J. Clin. Nutr. 1990;51:1106–1112. doi: 10.1093/ajcn/51.6.1106. PubMed PMID: 2349926. [DOI] [PubMed] [Google Scholar]
- 10.Svendsen O.L., Haarbo J., Heitmann B.L., Gotfredsen A., Christiansen C. Measurement of body fat in elderly subjects by dual-energy x-ray absorptiometry, bioelectrical impedance, and anthropometry. Am. J. Clin. Nutr. 1991;53:1117–1123. doi: 10.1093/ajcn/53.5.1117. PubMed PMID: 2021122. [DOI] [PubMed] [Google Scholar]
- 11.Kamimura M.A., Avesani C.M., Cendoroglo M., Canziani M.E., Draibe S.A., Cuppari L. Comparison of skinfold thicknesses and bioelectrical impedance analysis with dual-energy X-ray absorptiometry for the assessment of body fat in patients on long-term haemodialysis therapy. Nephrol. Dial. Transplant. 2003;18:101–105. doi: 10.1093/ndt/18.1.101. 10.1093/ndt/18.1.101 PubMed PMID: 12480966. [DOI] [PubMed] [Google Scholar]
- 12.Kyle U.G., Bosaeus I., De Lorenzo A.D., Deurenberg P., Elia M., Gómez J.M., Heitmann B.L., Kent-Smith L., Melchior J.C., Pirlich M., Scharfetter H., Schols A.M.W.J., Pichard C. Bioelectrical impedance analysis — part II: utilization in clinical practice. Clin. Nutr. 2004;23:1430–1453. doi: 10.1016/j.clnu.2004.09.012. 10.1016/j.clnu.2004.09.012 PubMed PMID: 15556267. [DOI] [PubMed] [Google Scholar]
- 13.Horber F.F., Thomi F., Casez J.P., Fonteille J., Jaeger P. Impact of hydration status on body composition as measured by dual energy x-ray absorptiometry in normal volunteers and patients on haemodialysis. Br. J. Radiol. 1992;65:895–900. doi: 10.1259/0007-1285-65-778-895. 10.1259/0007-1285-65-778-895 PubMed PMID: 1422663. [DOI] [PubMed] [Google Scholar]
- 14.Glüer C.C., Blake G., Lu Y., Blunt B.A., Jergas M., Genant H.K. Accurate assessment of precision errors: how to measure the reproducibility of bone densitometry techniques. Osteoporos Int. 1995;5:262–270. doi: 10.1007/BF01774016. 10.1007/BF01774016 PubMed PMID: 7492865. [DOI] [PubMed] [Google Scholar]
- 15.Roubenoff R., Baumgartner R.N., Harris T.B., Dallal G.E., Hannan M.T., Economos C.D., Stauber P.M., Wilson P.W.F., Kiel D.P. Application of bioelectrical impedance analysis to elderly populations. J. Gerontol. 1997;52A:M129–M136. doi: 10.1093/gerona/52a.3.m129. [DOI] [PubMed] [Google Scholar]
- 16.Montgomery D.C. Design and analysis of experiments. John Wiley & Sons; New York: 1996. [Google Scholar]
- 17.Salamone L.M., Fuerst T., Visser M., Kern M., Lang T., Dockrell M., Cauley J., Nevitt M., Tylavsky F., Lohman T. Measurement of fat mass using DEXA: a validation study in elderly adults. J. Appl. Physiol. 2000;89:345–352. doi: 10.1152/jappl.2000.89.1.345. PubMed PMID: 10904070. [DOI] [PubMed] [Google Scholar]
- 18.Roubenoff R. Sarcopenia: Effects on body composition and function. J. Gerontol. 2003;58A:1012–1017. doi: 10.1093/gerona/58.11.m1012. [DOI] [PubMed] [Google Scholar]
- 19.Visser M., Fuerst T., Lang T., Salamone L., Harris T.B. Validity of fan-beam dualenergy X-ray absorptiometry for measuring fat-free mass and leg muscle mass. J. Appl. Physiol. 1999;87:1513–1520. doi: 10.1152/jappl.1999.87.4.1513. PubMed PMID: 10517786. [DOI] [PubMed] [Google Scholar]
- 20.Rallison L.R., Kushner R.F., Penn D., Schoeller D.A. Errors in estimating peritoneal fluid by bioelectrical impedance analysis and total body electrical conductivity. J. Am. Coll. Nutr. 1993;12:66–72. doi: 10.1080/07315724.1993.10718285. PubMed PMID: 8382711. [DOI] [PubMed] [Google Scholar]
- 21.Foster K.R., Lukaski H.C. Whole-body impedance — What does it measure? Am. J. Clin. Nutr. 1996;64:388S–396S. doi: 10.1093/ajcn/64.3.388S. PubMed PMID: 8780354. [DOI] [PubMed] [Google Scholar]
- 22.Chumlea W.C., Baumgartner R.N. Bioelectrical impedance methods for the estimation of body composition. Can. J. Spt. Sci. 1990;15:172–179. [PubMed] [Google Scholar]
- 23.Bolanowski M., Nilsson B.O. Assessment of human body composition using dualenergy x-ray absorptiometry and bioelectrical impedance analysis. Med. Sci. Monit. 2001;7:1029–1033. PubMed PMID: 11535954. [PubMed] [Google Scholar]
- 24.Sun G., French C.R., Martin G.R., Younghusband B., Green R.C., Xie Y., Mathews M., Barron J.R., Fitzpatrick D.G., Gulliver W., Zhang H. Comparison of multifrequency bioelectrical impedance analysis with dual-energy x-ray absorptiometry for assessment of percentage body fat in a large, healthy population. Am. J. Clin. Nutr. 2005;81:74–78. doi: 10.1093/ajcn/81.1.74. PubMed PMID: 15640463. [DOI] [PubMed] [Google Scholar]