A hypocaloric diet impairs muscle protein synthesis[1][2][3] and increases muscle protein breakdown.[4] It can also unfavorably alter the anabolic hormone response to resistance exercise.[5] Furthermore, prolonged consumption of a hypocaloric diet can facilitate endocrine system dysfunction, resulting in a suppression of reproductive and metabolic hormones and unfavorable alterations in markers of bone metabolism.[6] For these reasons, a hypocaloric diet would be expected to negatively affect muscle strength.
However, a 2021 meta-analysis that compared the effects of performing resistance training in an energy deficit or without an energy deficit reported that, while an energy deficit impaired lean mass gains, it did not impair strength gains;[7] interventions that prescribed resistance training in an energy deficit and without an energy deficit both resulted in a large increase in muscle strength. Furthermore, the average energy deficit in the included studies was 567 kcal per day.
A caveat to these findings is that the studies included in this meta-analysis were between 3 and 28 weeks long, with an average intervention duration of about 16 weeks. While the results suggest that increases in muscle strength can occur in an energy deficit in the short term, spending too much time in an energy deficit will undoubtedly compromise long-term strength gains. This stems from the fact that, as outlined in “Which other factors affect muscle strength?,” differences in muscle mass largely explain differences in muscle strength. Because an energy surplus enhances muscle gain (while an energy deficit impairs gains in muscle mass and can cause muscle loss), and a larger muscle has greater force-generating capacity, individuals interested in maximizing strength gains should spend a notable amount of time performing resistance training in an energy surplus.
References
- ^Stefan M Pasiakos, Lisa M Vislocky, John W Carbone, Nicholas Altieri, Karen Konopelski, Hedley C Freake, Jeffrey M Anderson, Arny A Ferrando, Robert R Wolfe, Nancy R RodriguezAcute energy deprivation affects skeletal muscle protein synthesis and associated intracellular signaling proteins in physically active adultsJ Nutr.(2010 Apr)
- ^Hector AJ, McGlory C, Damas F, Mazara N, Baker SK, Phillips SMPronounced energy restriction with elevated protein intake results in no change in proteolysis and reductions in skeletal muscle protein synthesis that are mitigated by resistance exercise.FASEB J.(2018-Jan)
- ^José L Areta, Louise M Burke, Donny M Camera, Daniel W D West, Siobhan Crawshay, Daniel R Moore, Trent Stellingwerff, Stuart M Phillips, John A Hawley, Vernon G CoffeyReduced resting skeletal muscle protein synthesis is rescued by resistance exercise and protein ingestion following short-term energy deficitAm J Physiol Endocrinol Metab.(2014 Apr 15)
- ^John W Carbone, Stefan M Pasiakos, Lisa M Vislocky, Jeffrey M Anderson, Nancy R RodriguezEffects of short-term energy deficit on muscle protein breakdown and intramuscular proteolysis in normal-weight young adultsAppl Physiol Nutr Metab.(2014 Aug)
- ^Chaise Murphy, Karsten KoehlerCaloric restriction induces anabolic resistance to resistance exerciseEur J Appl Physiol.(2020 May)
- ^José L Areta, Harry L Taylor, Karsten KoehlerLow energy availability: history, definition and evidence of its endocrine, metabolic and physiological effects in prospective studies in females and malesEur J Appl Physiol.(2021 Jan)
- ^Chaise Murphy, Karsten KoehlerEnergy deficiency impairs resistance training gains in lean mass but not strength: A meta-analysis and meta-regressionScand J Med Sci Sports.(2021 Oct 8)