Calculation of protein requirements; a comparison of calculations based on bodyweight and fat free mass.

BACKGROUND & AIMS: In dietary practice, it is common to estimate protein requirements on actual bodyweight, but corrected bodyweight (in cases with BMI <20 kg/m2 and BMI ≥30 kg/m2) and fat free mass (FFM) are also used. Large differences on individual level are noticed in protein requirements using these different approaches. To continue this discussion, the answer is sought in a large population to the following question: Will choosing actual bodyweight, corrected bodyweight or FFM to calculate protein requirements result in clinically relevant differences? METHODS: This retrospective database study, used data from healthy persons ≥55 years of age and in- and outpatients ≥18 years of age. FFM was measured by air displacement plethysmography technology or bioelectrical impedance analysis. Protein requirements were calculated as 1) 1.2 g (g) per kilogram (kg) actual bodyweight or 2) corrected bodyweight or 3) 1.5 g per kg FFM. To compare these three approaches, the approach in which protein requirement is based on FFM, was used as reference method. Bland-Altman plots with limits of agreement were used to determine differences, analyses were performed for both populations separately and stratified by BMI category and gender. RESULTS: In total 2291 subjects were included. In the population with relatively healthy persons (n = 506, ≥55 years of age) mean weight is 86.5 ± 18.2 kg, FFM is 51 ± 12 kg and in the population with adult in- and outpatients (n = 1785, ≥18 years of age) mean weight is 72.5 ± 18.4 kg, FFM is 51 ± 11 kg. Clinically relevant differences were found in protein requirement between actual bodyweight and FFM in most of the participants with overweight, obesity or severe obesity (78-100%). Using corrected bodyweight, an overestimation in 48-92% of the participants with underweight, healthy weight and overweight is found. Only in the Amsterdam UMC population, protein requirement is underestimated when using the approach of corrected bodyweight in participants with severe obesity. CONCLUSION: The three approaches in estimation of protein requirement show large differences. In the majority of the population protein requirement based on FFM is lower compared to actual or corrected bodyweight. Correction of bodyweight reduces the differences, but remain unacceptably large. It is yet unknown which method is the best for estimation of protein requirement. Since differences vary by gender due to differences in body composition, it seems more accurate to estimate protein requirement based on FFM. Therefore, we would like to advocate for more frequent measurement of FFM to determine protein requirements, especially when a deviating body composition is to be expected, for instance in elderly and persons with overweight, obesity or severe obesity.

Instrumented measures of sedentary behaviour and physical activity are associated with mortality in community-dwelling older adults: A systematic review, meta-analysis and meta-regression analysis.

BACKGROUND: Sedentary behaviour (SB) and physical activity (PA) can be objectively assessed with inertial sensors to describe bodily movement. Higher SB and lower PA is associated with higher chronological age and negative health outcomes. This study aimed to quantify the association between instrumented measures of SB (i-SB) and PA (i-PA) and mortality in community-dwelling older adults, to subsequently compare the quantitative effect sizes and to determine the dose-response relationships. METHODS: An electronic search in six databases from inception to 27th of June 2019 was conducted. All articles reporting on i-SB or i-PA and mortality in community-dwelling older adults aged 60 years or older were considered eligible. A meta-analysis was conducted for the association between i-SB and i-PA and mortality expressed in Hazard Ratios (HR) and 95% Confidence Intervals (95% CI). A meta-regression analysis was performed to determine the dose-response relationship between i-SB and steps per day and mortality. RESULTS: Twelve prospective articles representing eleven cohorts, reporting data of 38,141 participants were included. In total 2502 (6.4%) participants died during follow-up (2.0 to 9.8 years). Comparing the most sedentary with the least sedentary groups of participants resulted in a pooled HR of 2.44 (95% CI 1.82-3.25). Comparing the least active with the most active groups of participants resulted in a pooled HR of 1.93 (95% CI 1.39-2.69); 2.66 (95% CI 2.11-3.35); 3.43 (95% CI 2.61-4.52), and 3.09 (95% CI 2.33-4.11) for light, moderate-to-vigorous-, total PA and steps per day, respectively. Meta-regression analyses showed clear dose-response relationships between i-SB and steps per day and mortality risk. CONCLUSION: Both i-SB and i-PA are significantly associated with mortality in community-dwelling older adults, showing the largest effect size for total physical activity. Dose-response relationships could be observed for i-SB and steps per day.