High-Protein Energy-Restriction: Effects on Body Composition, Contractile Properties, Mood, and Sleep in Active Young College Students

Abstract

Background: It is often advised to ensure a high-protein intake during energy-restricted diets. However, it is unclear whether a high-protein intake is able to maintain muscle mass and contractility in the absence of resistance training.Materials and Methods: After 1 week of body mass maintenance (45 kcal/kg), 28 male college students not performing resistance training were randomized to either the energy-restricted (ER, 30 kcal/kg, n = 14) or the eucaloric control group (CG, 45 kcal/kg, n = 14) for 6 weeks. Both groups had their protein intake matched at 2.8 g/kg fat-free-mass and continued their habitual training throughout the study. Body composition was assessed weekly using multifrequency bioelectrical impedance analysis. Contractile properties of the m. rectus femoris were examined with Tensiomyography and MyotonPRO at weeks 1, 3, and 5 along with sleep (PSQI) and mood (POMS).Results: The ER group revealed greater reductions in body mass (Δ −3.22 kg vs. Δ 1.90 kg, p < 0.001, partial η2 = 0.360), lean body mass (Δ −1.49 kg vs. Δ 0.68 kg, p < 0.001, partial η2 = 0.152), body cell mass (Δ −0.85 kg vs. Δ 0.59 kg, p < 0.001, partial η2 = 0.181), intracellular water (Δ −0.58 l vs. Δ 0.55 l, p < 0.001, partial η2 = 0.445) and body fat percentage (Δ −1.74% vs. Δ 1.22%, p < 0.001, partial η2 = 433) compared to the CG. Contractile properties, sleep onset, sleep duration as well as depression, fatigue and hostility did not change (p > 0.05). The PSQI score (Δ −1.43 vs. Δ −0.64, p = 0.006, partial η2 = 0.176) and vigor (Δ −2.79 vs. Δ −4.71, p = 0.040, partial η2 = 0.116) decreased significantly in the ER group and the CG, respectively.Discussion: The present data show that a high-protein intake alone was not able to prevent lean mass loss associated with a 6-week moderate energy restriction in college students. Notably, it is unknown whether protein intake at 2.8 g/kg fat-free-mass prevented larger decreases in lean body mass. Muscle contractility was not negatively altered by this form of energy restriction. Sleep quality improved in both groups. Whether these advantages are due to the high-protein intake cannot be clarified and warrants further study. Although vigor was negatively affected in both groups, other mood parameters did not change.

Lean mass sparing in resistance-trained athletes during caloric restriction: the role of resistance training volume

“…During CR, activation of mTORC1 and its downstream targets, as well as MPS is reduced, while proteolysis appears to be increased (Margolis et al 2016 ; Carbone et al 2014 ; Berryman et al 2017 ); however, the results in this regard are somewhat conflicting (Carbone et al 2019 ). Without any counteracting stimuli (e.g., RT), attenuation of MPS ultimately leads to a negative net protein balance and, hence, to lean tissue loss (Roth et al 2021 ; Pasiakos et al 2013 ). This is supported by the data of athletes taking performance-enhancing drugs who, due to ergogenic effects on protein turnover, do not show significant lean tissue loss (Pasiakos et al 2019 ; de Souza et al 2018 ; Howard et al 2020 ).…”

Resistance training volume does not influence lean mass preservation during energy restriction in trained males

“…7 We lowered the effect size to account for individual variability in lean mass loss. 15 An a priori power analysis was performed using G*Power 3.1 (University Duesseldorf, GER) which revealed that 38 participants were required to achieve a power = 0.80, an effect size of f = 0.23, and an α = 0.05.…”

“…For the daily weigh-ins, the participants reported body mass to the nearest 0.1 kg on their own digital scale wearing only underwear after an overnight fast and after emptying their bladder. The dietary prescription employed during the study was adapted from Roth et al 15 Briefly, during the familiarization phase all participants consumed 45 kcal/kg for weight maintenance, followed by a six-week hypocaloric period (30 kcal/kg); the energy deficit in the hypocaloric intervention is consistent with recommendations for natural bodybuilders during contest preparation. 18 Protein intake was set at 2.8 g/kg fat-free mass (FFM) in both groups throughout the study period, 19 with the remaining energy distributed between carbohydrates and fats based on individual preference.…”

“…The assessment adhered to ESPEN guidelines, with the detailed testing procedure described elsewhere. 15 Briefly, MFBIA (whole-body) was tested foot-to-hand on the dominant side of the body in a supine position at weeks 1, 4, and 6. Participants were tested subsequent to an overnight fast and after emptying their bladder.…”

“…TMG description and conduction of measurements are extensively described elsewhere. 15 Briefly, self-adhesive gel electrodes (dura-stick plus, 50 × 50 mm) were attached with an inter-electrode distance of 5 cm. In order to keep the leg angle constant at 120°, the TMG leg cushion for thigh measurements was placed under the knee joint.…”