REF-879 · Helms et al., 2014 · International Journal of Sport Nutrition and Exercise Metabolism, Vol. · Paper · PubMed

A Systematic Review of Dietary Protein During Caloric Restriction in Resistance Trained Lean Athletes: A Case for Higher Intakes

A-fairly strong evidenceMeasured on a mixed groupWritten before October 2026, being re-checked

When athletes cut calories to lose fat or make weight, their protein needs may rise, especially when they are already lean. This systematic review searched databases to July 2013 for studies of energy-restricted, resistance-trained (> 6 months) adults with lower body fat (men ≤ 23%, women ≤ 35%) that reported protein intake, fat-free mass (FFM) and body fat.

Six studies (13 groups) qualified. Body fat fell in every group and FFM fell in nine of 13. The groups that kept FFM were mostly those with more body fat, a smaller deficit or a new training stimulus — except one lean, substantially restricted group without a new stimulus, which ate the most protein (2.5-2.6 g/kg).

The authors conclude that protein needs for energy-restricted, resistance-trained athletes are likely 2.3-3.1 g/kg of FFM, scaled upwards with the severity of the deficit and leanness.

Participants

6 studies (abstract: "Studies (N = 6)") comprising 13 study groups of adults (≥ 18 yrs), resistance-trained (> 6 months), with lower body fat (males ≤ 23%, females ≤ 35%), under energy restriction while resistance training.

Protocol

Database searches from earliest record to July 2013 (protein, intake/diet, weight, train, restrict, energy, strength, athlete).
Inclusion: adult, energy-restricted, resistance-trained, lean, performing resistance training; protein intake, FFM and body fat reported.
Narrative synthesis across groups; no meta-analysis.

Key Results

Body fat percentage decreased 0.5-6.6% in all 13 groups.
FFM decreased 0.3-2.7 kg in nine of 13 groups.
Six groups gained, did not lose, or lost non-significant FFM; five of these six were among the highest in body fat, lowest in caloric restriction, or had a novel resistance-training stimulus.
The one group that was lean, substantially restricted and without a novel stimulus yet kept FFM ate the most protein of all groups: 2.5-2.6 g/kg.
Authors' recommendation: 2.3-3.1 g/kg of FFM, scaled up with the severity of caloric restriction and leanness.

Practical Application

Across 6 studies (13 groups) of lean, resistance-trained adults cutting calories, most groups lost some fat-free mass (0.3-2.7 kg in nine of 13); the only lean, hard-dieting group that kept it ate the most protein (2.5-2.6 g/kg), and the authors recommend 2.3-3.1 g/kg of fat-free mass, higher the leaner you are and the bigger the deficit. To "how much protein do I need while I'm losing weight?": more than usual — the review's range is per kg of fat-free mass, not body mass, and sits at its top end for an already-lean athlete in a steep deficit.
The range is expressed per kg of FFM; for a lean athlete that is a smaller number than the same figure per kg of body mass.
Keep lifting: the groups that held FFM often had a new resistance-training stimulus.
Inference, not tested here: the studies are resistance-trained populations; how the range transfers to an endurance athlete doing high aerobic volume in a deficit is not known.
Not from this paper; the base's own practice: SYNTH-54 screens for low energy availability before any deficit and keeps it slow; the same hypocaloric range appears in the ISSN position stand REF-578.

Limitations

Only 6 studies (13 groups), small and heterogeneous; no pooled estimate and no formal dose-response.
The recommended range is the authors' reading across groups that also differed in body fat, deficit size and training stimulus.
Resistance-trained populations; endurance athletes were not the target.
Written from the abstract and record metadata only (full text not read).
How this entry was checked and changed
Why this level

systematic review of few, small studies with no pooled estimate