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Front. Nutr. | doi: 10.3389/fnut.2019.00102

Influence of fish oil-derived n-3 fatty acid supplementation on changes in body composition and muscle strength during short-term weight loss in resistance-trained men

  • 1Physiology, Exercise and Nutrition Research, Faculty of Health Sciences and Sport, University of Stirling, United Kingdom
  • 2School of Exercise and Nutrition Sciences, Deakin University, Australia
  • 3Institute of Aquaculture, Faculty of Natural Sciences, University of Stirling, United Kingdom
  • 4Department of Health Sciences and Technology, ETH Zürich, Switzerland
  • 5Department of Sport, Exercise and Physical Activity, School of Applied Social Sciences, Durham University, United Kingdom

Background: A common detrimental consequence of diet-induced weight loss is muscle loss. Dietary omega-3 polyunsaturated fatty acids (n-3PUFA) exhibit a protective effect on the loss of muscle tissue during catabolic situations such as injury-simulated leg immobilisation. This study aimed to investigate the influence of dietary n-3PUFA supplementation on changes in body composition and muscle strength following short-term diet-induced weight loss in resistance-trained men.
Methods: Twenty resistance-trained young (23 ± 1 yrs) men were assigned to a fish oil supplementation group containing 4g n-3PUFA, 18g carbohydrate and 5g protein (FO) or placebo group containing an equivalent carbohydrate and protein content (CON) over a 6 wk period. During wks 1-3, participants continued their habitual diet. During wk 4, participants received all food items to control energy balance and a macronutrient composition of 50% carbohydrate, 35% fat and 15% protein. During wks 5 and 6, participants were fed an energy-restricted diet equivalent to 60% habitual energy intake. Body composition and strength were measured during wks 1, 4 and 6.
Results: The decline in total body mass (FO = -3.0 ± 0.3 kg, CON = -2.6 ± 0.3 kg), fat free mass (FO = -1.4 ± 0.3 kg, CON = -1.2 ± 0.3 kg) and fat mass (FO = -1.4 ± 0.2 kg, CON = -1.3 ± 0.3 kg) following energy restriction was similar between groups (all p > 0.05; d: 0.16-0.39). Non-dominant leg extension 1RM increased (6.1 ± 3.4 %) following energy restriction in FO (p < 0.05, d = 0.29), with no changes observed in CON (p > 0.05, d = 0.05). Dominant leg extension 1RM tended to increase following energy restriction in FO (p = 0.09, d = 0.29), with no changes in CON (p > 0.05, d = 0.06). Changes in leg press 1RM, maximum voluntary contraction and muscular endurance following energy restriction were similar between groups (p > 0.05, d = 0.05).
Conclusion: Any possible improvements in muscle strength during short-term weight loss with n-3PUFA supplementation are not related to the modulation of FFM in resistance-trained men.

Keywords: Omega-3 polyunsaturated fatty acids (n-3 PUFAs), Energy restriction, Fat-free mass, fat mass, performance, Athletes

Received: 06 Apr 2019; Accepted: 20 Jun 2019.

Edited by:

Daniel Moore, University of Toronto, Canada

Reviewed by:

Gordon Smith, Washington University in St. Louis, United States
Philip Chilibeck, University of Saskatchewan, Canada  

Copyright: © 2019 Philpott, Bootsma, Hamilton, Mackinlay, Dick, Mettler, Galloway, Tipton and Witard. 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.

* Correspondence: Dr. Oliver Witard, Physiology, Exercise and Nutrition Research, Faculty of Health Sciences and Sport, University of Stirling, Stirling, FK9 4LA, Scotland, United Kingdom, oliver.witard@stir.ac.uk