Higher Protein Intake Did Not Prevent Muscle Loss During a Calorie Deficit Without Strength Training
Both is best.
This study, published in Frontiers in Sports and Active Living, investigated the effects of a high-protein, moderately energy-restricted diet on body composition, muscle contractile properties, mood, and sleep in active male college students who did not perform resistance training. The aim was to determine whether such a diet could preserve lean body mass and muscle function during energy restriction.
PMID: 34212136
Key Points
Aim: To assess whether a high-protein diet (2.8 g/kg fat-free mass) combined with moderate energy restriction (30 kcal/kg) preserves lean body mass and muscle contractility in the absence of resistance training.
Participants: 28 healthy male college students (aged ~26 years) with no prior resistance training experience, divided into an energy-restricted group (ER) and a eucaloric control group (CG).
Methods:
Weekly assessments of body composition using bioelectrical impedance analysis.
Muscle contractility was measured at weeks 1, 3, and 5 using Tensiomyography and MyotonPRO.
Mood and sleep quality were evaluated using standardised questionnaires (POMS and PSQI).
Diet Protocol: Both groups consumed 2.8 g/kg fat-free mass of protein daily. The ER group reduced caloric intake to 30 kcal/kg for six weeks, while the CG maintained intake at 45 kcal/kg.
Results
Body Composition:
ER group experienced greater reductions in body mass (-3.22 kg vs. -1.90 kg), lean body mass (-1.49 kg vs. -0.68 kg), body cell mass (-0.85 kg vs. -0.59 kg), intracellular water (-0.58 L vs. -0.55 L), and body fat percentage (-1.74% vs. -1.22%) compared to CG (all p < 0.001).
High protein intake did not prevent lean mass loss during energy restriction.
Muscle Contractility:
No significant changes were observed in muscle contractile properties for either group (p > 0.05).
Mood and Sleep:
Sleep quality improved in both groups (p = 0.006 for PSQI score).
Vigour decreased significantly in both groups (p = 0.040), but other mood parameters like depression, fatigue, and hostility remained unchanged.
Related
Practical Takeaways
For lifters or fitness enthusiasts:
High protein intake alone (2.8 g/kg fat-free mass) is insufficient to fully preserve lean muscle mass during energy restriction without resistance training.
Muscle contractility remains unaffected by moderate caloric deficits if protein intake is high.
Sleep quality may improve during calorie restriction, but mood disturbances like reduced vigour could occur.
Resistance training should be incorporated during dieting to help maintain lean muscle mass.
Key Takeaways
A high-protein diet during moderate energy restriction leads to significant weight loss but does not prevent lean muscle loss entirely in the absence of resistance training.
Muscle contractile properties are preserved despite caloric deficits.
Sleep quality improves slightly during dieting, but vigour may decline regardless of caloric intake levels.
Future studies should explore whether higher protein levels or additional interventions like resistance training can further mitigate muscle loss during dieting.
This study highlights the importance of combining sufficient protein intake with strength training for optimal results in preserving muscle during weight loss phases.
Reference
Roth C, Rettenmaier L, Behringer M. High-Protein Energy-Restriction: Effects on Body Composition, Contractile Properties, Mood, and Sleep in Active Young College Students. Front Sports Act Living. 2021 Jun 15;3:683327. doi: 10.3389/fspor.2021.683327. Erratum in: Front Sports Act Living. 2021 Nov 08;3:762606. doi: 10.3389/fspor.2021.762606. PMID: 34212136; PMCID: PMC8239143.