Frontiers in Nutrition 01 frontiersin.org Timing matters? The effects of two different timing of high protein diets on body composition, muscular performance, and biochemical markers in resistance-trained males Mohammadyasin Lak 1 , Reza Bagheri 2 *, Hamid Ghobadi 3 , Bill Campbell 4 , Alexei Wong 5 , Amin Shahrbaf 6 *, Mohammad Shariatzadeh 1 and Fred Dutheil 7 1 Sport Sciences Research Institute of Iran, Tehran, Iran, 2 Department of Exercise Physiology, University of Isfahan, Isfahan, Iran, 3 Department of Exercise Physiology, Ferdowsi University of Mashhad, Mashhad, Iran, 4 Performance and Physique Enhancement Laboratory, University of South Florida, Tampa, FL, United States, 5 Department of Health and Human Performance, Marymount University, Arlington, TX, United States, 6 Faculty of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran, 7 Université Clermont Auvergne CNRS, LaPSCo, Physiological and Psychosocial Stress, CHU Clermont-Ferrand, University Hospital of Clermont-Ferrand, Preventive and Occupational Medicine, Clermont-Ferrand, France Background: It is unclear whether resistance training in combination with different timing of protein intake might have differential effects on muscle hypertrophy, strength, and performance. Therefore, we compared the effects of 8  weeks of resistance training combined with two different high-protein diet strategies (immediately pre-and after, or 3  h pre and after exercise) in resistance- trained males. Methods: Forty resistance-trained males (24 ±  4  years) performed 8  weeks of resistance training combined with 2  g  kg −1  d −1 protein. Body composition, muscular performance, and biochemical markers were assessed pre and post- intervention. Results: Nine participants (four from 3  h group and five from the immediate group) withdrew from the study. Therefore, 31 participants completed the study. All measures of skeletal muscle mass, Australian pull-up, and muscle strength, significantly increased post-intervention in both groups (p <  0.05). The biochemical marker urea also significantly increased from pre to post in both groups (p <  0.05). There were no significant between-group differences (p >  0.05). Conclusion: High-protein diet enhances muscular performance and skeletal muscle mass in resistance-trained males, irrespective of intake time. Consequently, the total daily protein intake appears to be the primary factor in facilitating muscle growth induced by exercise. KEYWORDS exercise, dietary protein, nutrition, muscle hypertrophy, strength OPEN ACCESS EDITED BY José Joaquín Muros, University of Granada, Spain REVIEWED BY Robert Percy Marshall, RasenBallsport Leipzig GmbH/University Hospital Halle, Germany Paul A. Roberson, University of Colorado Anschutz Medical Campus, United States *CORRESPONDENCE Reza Bagheri Will.fivb@yahoo.com Amin Shahrbaf Aminshahrbaf41@gmail.com RECEIVED 06 March 2024 ACCEPTED 29 April 2024 PUBLISHED 23 May 2024 CITATION Lak M, Bagheri R, Ghobadi H, Campbell B, Wong A, Shahrbaf A, Shariatzadeh M and Dutheil F (2024) Timing matters? The effects of two different timing of high protein diets on body composition, muscular performance, and biochemical markers in resistance-trained males. Front. Nutr. 11:1397090. doi: 10.3389/fnut.2024.1397090 COPYRIGHT © 2024 Lak, Bagheri, Ghobadi, Campbell, Wong, Shahrbaf, Shariatzadeh and Dutheil. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms. TYPE Original Research PUBLISHED 23 May 2024 DOI 10.3389/fnut.2024.1397090