A systematic review of dietary protein during caloric restriction in resistance trained lean athletes: a case for higher intakes.
Level 1 - systematic review of randomized trials
Systematic review of interventional studies in resistance-trained humans
PubMed 24092765 · doi:10.1123/ijsnem.2013-0054
What was done
A systematic review was conducted of studies published up to July 2013 evaluating the effect of dietary protein intake on body composition in energy-restricted, resistance-trained adults (aged ≥18 years, training experience >6 months, baseline body fat ≤23% for males and ≤35% for females). Six studies comprising 13 intervention groups were identified that reported protein intake, fat-free mass (FFM), and body fat changes.
What was found
Body fat percentage decreased across all 13 study groups by 0.5% to 6.6%. Fat-free mass decreased by 0.3 to 2.7 kg in 9 of the 13 groups. Six groups preserved or gained FFM; five of these six had higher baseline body fat, lower caloric deficits, or unaccustomed training stimuli. The single lean group undergoing substantial energy restriction without novel training stimuli that preserved FFM consumed the highest protein intake (2.5–2.6 g/kg). Based on these patterns, the authors suggested protein requirements range from 2.3 to 3.1 g/kg FFM during caloric restriction.
Why it matters
It synthesizes available evidence to establish higher protein targets specifically for lean, resistance-trained athletes attempting to lose body fat while minimizing lean tissue loss.
Limits
The review included only 6 studies, and total participant count was not reported in the abstract. Interventions differed in the severity of energy restriction, baseline adiposity, and whether resistance training protocols provided a novel stimulus, confounding direct comparisons.
Cited by
- supports A meta-regression by Eric Helms showed that protein intakes up to approximately 3.1 grams per kilogram of lean mass improved lean mass retention during a caloric deficit.