Joseph J Matthews, Gohar Azhar, Katie R Hirsch, Robert R Wolfe, David D Church, Arny A Ferrando, Shiloah A Kviatkovsky, Reino A Henderson
Journal: The Journal of nutrition 2025;155(5):1364-1372
PMID: 39736329
Fasting has become popular for weight loss, maintenance and other health reasons. However, fasting may be associated with the loss of lean body mass due to an extended period of time during which protein is broken down. In older adults this may be particularly problematic as less muscle is associated with poorer health outcomes. This randomised control trial of 30 individuals aged 50-70 years investigated how different daily protein intakes affect protein turnover in middle-aged and older adults who eat two meals a day. Protein turnover refers to the balance between protein breakdown and building new proteins.
The results showed that protein intakes of 1.5 g/kg/d gave a better protein balance than amounts of 0.8 g/kg/d and 1.1 g/kg/d, which may be important for maintaining muscle mass and overall health in older adults. However, muscle protein synthesis was not affected by different protein amounts.
It was concluded that when eating a 2-meal dietary plan, a large amount of dietary protein is require to achieve a net positive protein balance. This study could be used by healthcare professionals to understand that individuals on a 2-meal dietary plan may require a larger amount of dietary protein in order to preserve lean muscle mass and longevity. Research on how exercise affects muscle building in individuals undergoing a fasting eating pattern may also be of benefit.
BACKGROUND
Reduced meal frequency patterns have become popular for weight loss, maintenance, and improving cardiometabolic health. The extended fasting windows with these dietary patterns could lead to greater protein breakdown, which is a concern for middle-aged and older adults who may need higher protein intakes to maintain or increase net protein balance.
OBJECTIVES
This study aimed to quantify muscle and whole-body protein kinetic responses to 3 different daily protein intakes within a 2-meal eating pattern.
METHODS
Thirty participants (age: 61 ± 6 y, BMI: 26.5 ± 4.8 kg/m) participated in this 24-h metabolic study using oral stable isotope tracer techniques and were randomized to 1 of 3 protein intakes: 1) recommended dietary allowance (RDA): 0.8 g/kg/d; 2) habitual United States intake: 1.1 g/kg/d; or 3) ≈2RDA: 1.5 g/kg/d distributed across 2 meals, consumed within a 9-h window.
RESULTS
Whole-body net protein balance was significantly higher for 1.5 g/kg/d compared with 0.8 g/kg/d [mean difference: 0.55 g/kg; lean body mass (LBM)/d; 95% confidence interval (CI): 0.17, 0.93 g/kg LBM/d; P = 0.004] and 1.1 g/kg/d (mean difference: 0.6 g/kg LBM/d; 95%CI: 0.23, 0.97 g/kg LBM/d; P = 0.001), with no difference between 0.8 and 1.1 g/kg/d (mean difference: 0.05 g/kg LBM/d; 95%CI: -0.31, 0.40 g/kg LBM/d; P = 0.936). Muscle protein synthesis was not significantly different between any groups (P = 0.388).
CONCLUSION
s: Within a 2-meal eating pattern, a protein intake of 1.5 g/kg/d led to a more positive whole-body net protein balance than intakes of 0.8 and 1.1 g/kg/d in middle-aged and older adults. This trial was registered at clinicaltrials.gov as NCT04830514.
Copyright © 2024. Published by Elsevier Inc.
© Copyright 2026, Nutrition Evidence
NED wishes to thank the following organisations for their support:
We use cookies to improve your experience and analyze site traffic with Google Analytics. By continuing to use our site, you agree to our use of cookies. Learn more.