Higher Protein Intake Does Not Improve Lean Mass Gain When Compared with RDA Recommendation in Postmenopausal Women Following Resistance Exercise Protocol: A Randomized Clinical Trial

Abstract

The aim of this study was to evaluate the effect of a higher protein intake on lean body mass (LBM) gain in postmenopausal women practicing resistance exercise and compare it to the Recommended Dietary Allowance (RDA) recommendation. Twenty-three postmenopausal women (63.2 ± 7.8 years) were randomized into two groups. The group with higher protein intake (n = 11) (HP) received a dietary plan with ~1.2 g·kg−1·day−1 of protein, while the normal protein (NP) group (n = 12) was instructed to ingest ~0.8 g·kg−1·day−1 of protein (RDA recommendation). Both groups performed the same resistance training protocol, 3 times a week, with progression of the number of sets (from 1 to 6 sets) and 8–12 repetitions. The intervention occurred over 10 weeks. Body composition evaluation was performed by dual-energy X-ray absorptiometry. The diet was evaluated by nine 24-h food recall summaries over the course of the study. During the intervention period, the HP group presented a higher protein (1.18 ± 0.3 vs. 0.87 ± 0.2 g·kg−1·day−1, p = 0.008) and leucine (6.0 ± 1.4 vs. 4.3 ± 0.9 g/day, p < 0.001) intake than the NP group, respectively. At the end of the intervention, there were increases in LBM both in HP (37.1 ± 6.2 to 38.4 ± 6.5 kg, p = 0.004) and in NP (37.6 ± 6.2 to 38.8 ± 6.4 kg, p < 0.001), with no differences between the groups (p = 0.572). In conclusion, increased protein intake did not promote higher LBM gain when compared to RDA recommendation in postmenopausal women performing resistance exercise during 10 weeks. This trial was registered at as NCT03024125.

Moderate Increase in Protein Intake Promotes a Small Additional Improvement in Functional Capacity, But Not in Muscle Strength and Lean Mass Quality, in Postmenopausal Women Following Resistance Exercise: A Randomized Clinical Trial

“…However, it is important to remember that this does not invalidate our data, because when we performed the analyses without statistical imputation the results remained the same (Table S1). In addition, the dietary and body composition data evaluating only the individuals who completed the study (without intention-to-treat analysis) can be observed in our previous study [23] and the results remained the same of the present study.…”

“…Regarding total fat mass, (NP—pre: 28.6 ± 2.2 vs. post: 28.2 ± 1.6 kg; and HP—pre: 27.6 ± 1.7 vs. post: 28.2 ± 1.6 kg) no changes were noted after intervention ( p = 0.902), with no differences for group ( p = 0.842) and the time × group interaction ( p = 0.680). The effect of the intervention on body composition changes evaluating only the individuals who completed the study (without intention-to-threat analysis) can be observed in our previous publication [23].…”

“…Mean values of VO 2 and VCO 2 were used in the Weir equation for the REE measurement [39]. Additional information about the REE measurement was previously described [23]. For the calculation of total energy expenditure (TEE), the following formula was used: TEE = (REE × FA) + MET [40].…”

“…Evaluating older adults, Finger et al [22] performed a meta-analysis and observed that protein supplementation does not seem to promote additional strength gains; however, the studies included in the meta-analysis presented a great variation in additional protein doses (6 g to 0.8 g/kg), which makes it difficult to conclude if increased protein intake promotes further improvements in muscle function. Therefore, evaluating all these data together [20,22], it is unknown if a moderate increase in protein intake can promote additional strength and functional capacity gains when the baseline protein intake is ~0.8 g·kg −1 ·d −1 , which is commonly ingested by untrained postmenopausal women [18,23,24].…”

“…Our research group previously showed that a moderate increase in protein intake (~1.2 g·kg −1 ·d −1 ) does not promote additional lean mass gain in non-frail postmenopausal women performing resistance exercise when compared with RDA recommendations [23]. However, since the lean mass gain does not seem to determine strength and functional capacity improvements [30,31], it is necessary to evaluate the effect of these protein recommendations on strength and functional capacity.…”