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 disrupt endocrine system function, suppressing levels of reproductive and metabolic hormones and causing unfavorable changes in bone metabolism biomarkers.[6] For these reasons, a hypocaloric diet would be expected to negatively affect muscle size and strength.
A 2021 meta-analysis that compared the effects of performing resistance training in an energy deficit or without an energy deficit reported that an energy deficit impaired lean mass gains;[7] more specifically, it was estimated that an energy deficit of 500 kcal per day could prevent gains in lean mass. However, an energy deficit did not impair strength gains; interventions that prescribed resistance training with and without an energy deficit both resulted in a significant increase in muscle strength. The average energy deficit in these studies was 567 kcal per day.
A caveat to these findings is that the studies included in the above meta-analysis were between 3 and 28 weeks long, with an average intervention duration of 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. Because larger muscles have greater force-generating capacity,[8] and an energy surplus enhances muscle gain,[9] individuals interested in maximizing strength gains should spend a notable amount of time consuming a hypercaloric diet.
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)
- ^Taber CB, Vigotsky A, Nuckols G, Haun CTExercise-Induced Myofibrillar Hypertrophy is a Contributory Cause of Gains in Muscle StrengthSports Med.(2019 Jul)
- ^Aragon and SchoenfeldMagnitude and composition of the energy surplus for maximizing muscle hypertrophy: implications for bodybuilding and physique athletesStrength and Conditioning Journal.(2020-10)