Use of the air displacement plethysmograph to monitor body composition: a beneficial tool for dietitians

RMR Estimation Model Accuracy Using Air Displacement Plethysmography-Derived Body Composition Measures in Young Adults

OBJECTIVE

Predictive equations derived from regression techniques based on large samples are extensively utilized in estimating resting metabolic rate (RMR). Body composition assessments utilize model equations to estimate RMR. However, the agreement of these predictive models with indirect calorimetery (IC) has come into question. Our aim is to investigate the agreement of RMR estimation models using air displacement plethysmography (ADP) measures against a gas exchange IC system (RMR-C).

METHODS

Sixty-six participants (25 men, 41 women) completed the study. RMR measurements were obtained from IC and ADP within 10 minutes of one another. IC RMR estimates were tested against 9 other validated models using ADP measures via analysis of variance (ANOVA) techniques with multiple comparisons testing and Bland-Altman analysis.

RESULTS

Based on the ANOVA, the Nelson (1992) model underpredicted RMR compared to IC (p < 0.001). The Doré et al. (1982) model was the best predictor of RMR compared to the IC measures (p = 0.907).

DISCUSSION

The current RMR estimation model using ADP measures underpredicts total caloric needs. The Doré et al. (1982) model more accurately predicted RMR in the entire sample.

Effects of a supra-sustained gelatin-milk protein diet compared with (supra-)sustained milk protein diets on body-weight loss

Diets higher in protein content result in increased satiety and energy expenditure. In the short term, gelatin showed stronger hunger suppression and less subsequent energy intake compared with other proteins. The present study investigated whether a supra-sustained gelatin-milk protein (GMP) diet promotes weight loss compared with a sustained milk protein (SMP) diet and a supra-sustained milk protein (SSMP) diet during an 8-week diet period. A total of seventy-two healthy subjects (31·2 (sd 4·8) kg/m2; 43 (sd 10) years) followed one of the three diets in a subject-specific amount: SMP, SSMP or GMP diet. During weeks 1-4, energy intake was 100 % of individual energy requirement: 10, 40 and 50 % of energy (En %) as protein, fat and carbohydrate, respectively (SMP diet), and 20, 30 and 50 En % as protein, fat and carbohydrate, respectively (SSMP diet or GMP diet). During weeks 5-8, energy intake was 33 % of individual energy requirement: 30, 35 and 35 En % as protein, fat and carbohydrate, respectively (SMP diet), and 60, 5 and 35 En % as protein, fat and carbohydrate, respectively (SSMP diet or GMP diet). Thus, absolute protein intake was kept constant throughout per subject. Significant decreases in BMI (P < 0·0001) were similar between the GMP ( - 1·7 (sd 0·5) kg/m2) and the SMP ( - 2·1 (sd 0·8) kg/m2) and SSMP ( - 1·6 (sd 0·5) kg/m2) diets. Decreases in fat-free mass (FFM), fat mass (FM) and FM %, and increases in FFM % were similar between the GMP and both control diets. Changes in RQ differed (P < 0·05) between the GMP ( - 0·01 (sd 0·06)) and SSMP ( - 0·04 (sd 0·04)) diets. Changes in HDL concentrations differed (P < 0·05) between the GMP ( - 0·21 (sd 0·18) mmol/l) and the SMP and SSMP diets ( - 0·08 (sd 0·18) mmol/l and - 0·09 (sd 0·26) mmol/l, respectively). In conclusion, a gelatin-milk protein diet does not induce more beneficial effects during an 8-week weight-loss period compared with a SMP or SSMP diet.

No long-term weight maintenance effects of gelatin in a supra-sustained protein diet

In the short-term, gelatin showed stronger hunger suppression and less energy intake compared with other proteins. This study investigated if a supra-sustained gelatin-milk protein (GMP) diet improves weight maintenance (WM) compared with a sustained milk protein (SMP) diet and supra-sustained milk protein (SSMP) diet during a 4-months WM period after 8-week weight loss (WL) in sixty-five healthy subjects (28.6+/-3.4kg/m(2); 44+/-10years). Absolute protein intake was kept constant (sustained) throughout per subject. Diets were: protein(P)/fat(F)/carbohydrate(C): 15/40/45% of energy (En%) (SMP) and 30/25/45 En% (SSMP or GMP) for weeks 9-16. Diets on weeks 17-24: P/F/C: 30/35/35 En% (SMP) and 60/5/35 En% (SSMP or GMP). From weeks 8 to 16, and weeks 16 to 24, changes in BMI were similar between the GMP (-0.4+/-0.6 and 0.3+/-0.7kg/m(2) respectively), and the SMP (-0.7+/-0.9 and 0.1+/-0.7kg/m(2) respectively) and SSMP (-0.6+/-0.6 and 0.3+/-0.6kg/m(2) respectively) diets. Sparing of fat free mass (FFM): increases/decreases in FFM%/fat-mass% from weeks 8 to 16 were similar between the GMP and both control diets, and maintained from weeks 16 to 24. In conclusion, all 3 diets resulted in a successful WM period, while a GMP diet does not improve body weight maintenance and related variables after weight loss compared with a SMP and SSMP diet.