Body composition modeling. Application to exploration of the resting energy expenditure fat-free mass relationship

Monitoring Energy Metabolism with Indirect Calorimetry: Instruments, Interpretation, and Clinical Application

Indirect calorimetry is the best measure to guide calorie administration during nutrition support. This article presents an update of the types of currently available indirect calorimeters and reviews the recent advances that guide the clinical application of indirect calorimetry. The emphasis of this report is placed on issues that the practicing clinician can use to evaluate, interpret, and apply measurements of energy expenditure.

Regulation of energy expenditure by estradiol in premenopausal women

Suppressing sex hormones in women for 1 wk reduces resting energy expenditure (REE). The effects of more chronic suppression on REE and other components of total energy expenditure (TEE), and whether the reduction in REE is specifically due to loss of estradiol (E2), are not known. We compared the effects of 5 mo of sex hormone suppression (gonadotropin releasing hormone agonist therapy, GnRHAG) with placebo (PL) or E2 add-back therapy on REE and the components of TEE. Premenopausal women received GnRHAG (leuprolide acetate 3.75 mg/mo) and were randomized to receive transdermal therapy that was either E2 (0.075 mg/d; n = 24; means ± SD, aged = 37 ± 8 yr, BMI = 27.3 ± 6.2 kg/m(2)) or placebo (n = 21; aged = 34 ± 9 yr, BMI = 26.8 ± 6.2 kg/m(2)). REE was measured by using a metabolic cart, and TEE, sleep EE (SEE), exercise EE (ExEE, 2 × 30 min bench stepping), non-Ex EE (NExEE), and the thermic effect of feeding (TEF) were measured by using whole room indirect calorimetry. REE decreased in GnRHAG+PL [mean (95% CI), -54 (-98, -15) kcal/d], but not GnRHAG+E2 [+6 (-33, +45) kcal/d] (difference in between-group changes, P < 0.05). TEE decreased in GnRHAG+PL [-128 (-214, -41) kcal/d] and GnRHAG+E2 [-96 (-159, -32) kcal/d], with no significant difference in between-group changes (P = 0.55). SEE decreased similarly in both GnRHAG+PL [-0.07 (-0.12, -0.03) kcal/min] and GnRHAG+E2 [-0.07 (-0.12, -0.02) kcal/min]. ExEE decreased in GnRHAG+PL [-0.46 (-0.79, -0.13) kcal/min], but not GnRHAG+E2 [-0.30 (-0.65, +0.06) kcal/min]. There were no changes in TEF or NExEE in either group. In summary, chronic pharmacologic suppression of sex hormones reduced REE and this was prevented by E2 therapy.

Accuracy of predictive equations for resting metabolic rates and daily energy expenditures of police officials doing shift work by type of work

The purpose of this study was to analyze the accuracy of predictive equations for resting metabolic rate (RMR) and daily energy expenditure in policemen on a rotating shift. Subjects were 28 healthy policemen on a rotating shift (males) age of 23-46 years. The participants' RMR was measured by using indirect calorimetry (TrueOne2400) and also calculated from various predicted equations of RMR (Harris-Benedict, Schofield(W)/(WH), FAO/WHO/UNU(W)/(W/H), Cunningham, Mifflin, Liu, Owen, IMNA and Henry(W)/(WH)). The accuracy of these equations were evaluated on basis of accurate prediction (the percentage of subjects whose RMR was predicted within 90% to 110% of the RMR measured), mean difference, root mean squared prediction error, mean % difference, limits of agreement of Bland-Altman method between predicted and measured RMR. The measured RMR value of subjects was 1748 ± 205.9 kcal. Of the predictive equations tested, the Harris-Benedict equation (mean difference: -14.8 kcal/day, RMSPE: 195.8 kcal/day, mean % difference: 0.1%) was the most accurate and precise, but accuracy in prediction of the equation were only 35.7%. The daily energy expenditure at night-duty was 3062 kcal calculated as multiplying RMR by its physical activity level. Subsequently, daily energy expenditure of day-duty was 2647 kcal and the lowest daily energy expenditure was, 2310 kcal at holiday duty. Daily energy intake of all study participants was 2351 kcal at day-duty, 1959 kcal at night-duty and 1796 kcal at holiday-duty in order. The estimated energy requirements for policemen on a rotating shift on day shift, night shift and holiday came to 2743.6 kcal/day, 2998.6 kcal/day and 2576.9 kcal/day, respectively. These results suggest that estimated energy requirements (EER) of policemen on a rotating shift should be differently proposed by a proper equation which can closely reflect their metabolic status at each time shift.

Negative effects of obesity analyzed through bioimpedance, indirect calorimetry, the sympathovagal index and the orthoclinostatic test

Early analysis of the negative effects of obesity is important to prevent the development of chronic diseases related to this condition. There is a need to monitor these effects through simple instrumentation that measures fat-free mass (FFM) catabolism. Obesity leads to a decrease in the FFM energy expenditure and to an increase in the autonomic nervous system (ANS) activity. Thus, the measurement of FFM dynamic catabolism can provide information regarding the effects of obesity. The hypothesis is that this increased ANS activity produces an increase of energy expenditure of carbohydrates and fats when the subjects are under stress; in this case after an 8-hour fast and while they are undergoing an orthoclinostatic test. A pilot study was conducted on 29 volunteers, 16 women and 13 men. The results show significant statistical differences (p&#60;0.1) in fat and carbohydrate utilization during the orthoclinostatic tests: A move from the clinostatic to the orthostatic positions produced the following: Fat metabolism varied from 97.2 to 105.9 gr/day of fat for women and 24.9 to 35.7 gr/day of fat for men; carbohydrate metabolism changed from 38 to 39 gr/day for women and 239 to 277 gr/day for men; FFM averages were 47 Kg for women and 57.6 Kg for men; changes in the sympathovagal index (SVI) averages were 0.4 to 1.8 for women and 0.8 to 2.7 for men. The conclusions show that the methodology's sensitivity is such that gender differences can be used as a model to prove FFM metabolic differences. We believe that further studies will lead to the development of a robust methodology for the early detection of the negative effects of obesity.

Active metabolic weight estimation using bioimpedance, indirect calorimetry and the clino-ortho maneuver

The resting energy expenditure (REE) and substrate utilization are computed by indirect calorimetry technique (ICT). The REE represents 80-85% of the total energy expenditure (TEE) but only accounts for the 7% of the actual body weight (ABW). The TEE is produced by the organs plus muscles, whereas the REE accounts only for the main organs. An important problem comes up when the REE is computed throughout the fat free mass (FFM) computation or anthropometric measurements because they do not explain the tremendous catabolic variability by ICT when subjects show the same body composition. Therefore, the aim of this work is to develop a method to compute the metabolic active weight (MAW) as a new form that may help to understand the catabolic activity of the body composition. The premise was the clino-ortho maneuver can split the ABW in two parts: one in which the MAW reflects the FFM catabolism while the second part was not considered since there is not energy requirement in it. The experiment design studied 37 young volunteers undergoing the clino-ortho maneuver during fast and postprandial conditions. The results showed REE increments of 21% during phase I (fast), while in phase II (postprandial) only 14% was achieved in ortho-postprandial. Therefore, the computed MAWs were 65.5Kg and 58Kg, respectively, when the ABW average was 70 Kg and the FFM was 50 Kg. One first conclusion was that the 15.5 Kg of the MAW above the FFM could explain a catabolic equivalence which can be exclusively related to the fast-ortho position which can help to classify exclusively the dynamic over activity of the FFM.

Associations between energy demands, physical activity, and body composition in adult humans between 18 and 96 y of age

BACKGROUND

Associations between body composition and the energy expended on basal metabolism and activity are complex and age dependent.

OBJECTIVE

The objective was to examine associations between body composition and daily (DEE), basal (BEE), and activity energy expenditure (AEE) throughout the adult life span.

DESIGN

A cross-sectional study was conducted in 529 adults aged 18-96 y. DEE was measured by using doubly labeled water, BEE by using respirometry, and body composition by isotope dilution. AEE was calculated as DEE - BEE, and physical activity level (PAL) was calculated as DEE/BEE.

RESULTS

Up to age 52 y, fat-free mass (FFM) and fat mass (FM) were positively associated with age in men, but no significant effect was observed in women. No effects of age on DEE and AEE were observed. The average DEE in men (14.1 MJ/d) was 27% greater than that in women (10.7 MJ/d). PAL averaged 1.84 in men and 1.75 in women. Above and including the age of 52 y, FFM, FM, DEE, BEE, and AEE were all negatively associated with greater age. The effect of age on AEE was greater than on BEE; consequently, PAL by the age of 95 y was only 1.36. PAL and AEE were both unrelated to FFM (both age adjusted).

CONCLUSIONS

PAL and AEE were not associated with age in subjects aged <52 y. AEE, BEE, and PAL were all negatively associated with age in subjects aged ≥52 y. An absence of a relation between age-adjusted PAL and FFM suggested that greater physical activity was not associated with higher FFM in the elderly.

Validation of Cosmed's FitMate in measuring oxygen consumption and estimating resting metabolic rate

The purpose of this study was to assess the validity and reliability of the FitMate metabolic system (Cosmed, Rome, Italy) in measuring oxygen consumption and estimating resting metabolic rate (RMR). The FitMate is a new, small (20 x 24 cm) metabolic analyzer designed for measurement of oxygen consumption and energy expenditure during rest and exercise. Subjects included 60 healthy adults (N = 30 males, N = 30 females) ranging in age from 19 to 65 years (mean +/- SD age, 36.9 +/- 13.4 years) and body mass index (BMI) from 19.2 to 44.8 kg/m2 (27.7 +/- 6.2 kg/m2). Subjects were given two 10 min RMR tests in one test session during which RMR was measured simultaneously with the Douglas bag and FitMate systems. No significant differences were found between Douglas bag and FitMate systems for oxygen consumption (242 +/- 49 and 240 +/- 49 ml/min, respectively, P = 0.066, r = 0.97, mean +/- SD absolute difference 2.83 +/- 11.68 ml/min) or RMR (1,662 +/- 340 and 1,668 +/- 344 kcal/day, P = 0.579, r = 0.97, mean +/- SD absolute difference 5.81 +/- 80.70 kcal/day). These data indicate that the FitMate is a reliable and valid system for measuring oxygen consumption and RMR in adults.

A new handheld device for measuring resting metabolic rate and oxygen consumption

OBJECTIVE

The purpose of this study was to test a new handheld device, the BodyGem (HealtheTech Inc., Golden, CO), that measures resting metabolic rate (RMR).

SUBJECTS/DESIGN

Sixty-three adults (43 women, 20 men) (mean+/-SD, age 41.3+/-11.2 years and body mass index, 26.5+/-6.6 kg/m(2)) were tested during two separate sessions within a 2-week period, and, in each session, two BodyGem and two Douglas bag RMR measurements were made in a random and counterbalanced order.

MAIN OUTCOME MEASURES

Resting oxygen consumption and energy expenditure.

STATISTICAL ANALYSES PERFORMED

A 2 (methods) x 4 (time points) repeated measures ANOVA, Pearson product-moment coefficients, Bland-Altman plots.

RESULTS

Within session reliability for measurement of O(2), consumption was high on both days for the BodyGem (r=0.97). During the 4 single tests, BodyGem and Douglas bag O(2) consumption values were significantly correlated (r=0.81-0.87), with SEEs ranging from 22 to 28 mL. min(-1). Mean O(2) consumption and RMR values for all 4 tests were 241+/-46 and 240+/-45 mL x min(-1) (r=0.91, SEE 18.7 mL x min(-1)) and 1,657+/-324 and 1,650+/-307 kcals x day(-1) (r=0.91, SEE 134 kcals x day(-1)) for the BodyGem and Douglas bag methods, respectively.

APPLICATIONS/CONCLUSIONS

These data indicate that the BodyGem is an accurate and reliable device for measuring oxygen consumption and calculating RMR during repeated tests within a day, single tests on separate days, or when measurements are averaged.

Body composition and energy expenditure: relationship and changes in obese subjects before and after biliopancreatic diversion

Changes in total and segmental body composition were studied in 101 obese women before and 2, 6, 12, and 24 months after biliopancreatic diversion (BPD) and data 24 months after surgery were matched to 53 control subjects. The patients were studied by anthropometry, indirect calorimetry, and double-emission x-ray absorptiometry (DXA). The combination of calorimetry and body composition analysis allowed estimation of visceral and muscle lean mass. We observed a significant (analysis of variance [ANOVA]: P <.05) progressive reduction of fat and lean body mass (LBM) following BPD, with stabilization of both parameters between 12 and 24 months at levels not different from controls. Fat loss was significant in the arms, legs, and trunk segments. After 24 months, there was no significant difference in segmental fat mass between post-BPD patients and controls. Calorimetric data seem to confirm lean body mass (LBM) reduction. Visceral lean mass (kg) was significantly reduced from 8.1 +/- 2.2 in obese subjects to 6.5 +/- 1.8 in post-BPD patients at 24 months (P <.05); the control value was 7.2 +/- 1.8. Muscular lean mass (kg) was also significantly reduced, from 50.2 +/- 5.8 to 39.8 +/- 5.7 in the same subjects (P <.05), with a control value of 42.5 +/- 5.9. The decrease in muscle and visceral LBM reached control values without significant differences. Viscera/muscle ratio in pre-BPD patients was preserved in post-BPD patients at 24 months, but it was reduced during weight loss. Body composition studies showed a logarithmic relationship between fat and lean mass and a physiological contribution of lean mass to weight loss in the BPD patients. In conclusion, weight loss after BPD was achieved with an appropriate decline of LBM and with all parameters reaching, at stable weight, values similar to weight-matched controls.