Key Takeaways for Best Protein Intake While Dieting
- Higher protein intake helps retain muscle mass during dieting, with a recommended range of 0.86–1.45 grams per pound (1.9–3.2 grams per kilogram) of body weight per day.
- Leaner individuals require more protein, as they have fewer fat stores to rely on during a caloric deficit.
- A linear relationship exists between protein intake and fat-free mass retention, with higher intakes leading to better outcomes.
Best Protein Intake to Keep Your Gains While Dieting?
Every bodybuilder and fitness enthusiast knows that protein is essential for muscle growth. But when you are in a caloric deficit (i.e., dieting), how much protein should you eat to maintain your hard-earned muscle? A new study published in the Strength & Conditioning Journal provides a comprehensive answer. Conducted by Martin Refalo, Eric Trexler, and Eric Helms, the study analyzed 29 different studies to determine the best protein intake for muscle retention during weight loss.1
Unlike previous recommendations based on limited experimental data, this new research offers a more refined approach that accounts for factors like lean body mass and body fat percentage. Their findings suggest that eating at least 0.86 grams per pound (1.9 grams per kilogram) of body weight daily is necessary to prevent muscle loss. However, if you are lean, lifting heavy, and in a calorie deficit, you may benefit from even higher protein intake—up to 1.45 grams per pound (3.2 grams per kilogram) of body weight per day.
The Significance of Protein in Maintaining Muscle
Your body is in a catabolic condition when you lose weight, which means it uses both muscle and fat as fuel. Higher protein intake is crucial for preserving fat-free mass during caloric restriction. Studies show that young, healthy subjects undergoing a moderate energy deficit (750 kcal/day) significantly reduce muscle mass when protein intake is limited to the Recommended Dietary Allowance (RDA). However, those consuming higher protein levels (1.6 and 2.4 g/kg body mass) or 0.73 to 1.09 grams per pound of body weight per day can rescue muscle loss, suggesting that protein intake above the RDA is essential during periods of energy deficit.2 Hector et al. found that while increased protein intake did not completely prevent declines in muscle protein synthesis during energy restriction, it helped mitigate the loss, particularly when paired with resistance exercise.3
While on a calorie deficit, it supplies the building blocks (amino acids) required to maintain and rebuild muscle. Your body may break down muscle tissue to meet its energy needs if you don’t get enough protein.4 For this reason, determining the ideal protein consumption is crucial for anyone trying to maintain muscle mass while losing fat.
How Much Protein is Needed? Best Protein Intake Insights from Previous Studies
Several studies over the years have attempted to determine the best protein intake for muscle retention.
- Helms et al. (2014) recommended 2.3–3.1 grams per kilogram (1.04–1.4 grams per pound) of fat-free mass per day for lean, resistance-trained individuals in a caloric deficit.5 However, this range was based on limited experimental data, primarily from six studies.
- Pasiakos et al. (2013) demonstrated that higher protein diets could help preserve fat-free mass in a hypocaloric context, reinforcing the need for increased protein consumption to counteract muscle loss.6 However, this was a short-term study of military personnel.
- Longland et al. (2016) demonstrated that high-intensity resistance training combined with 2.4 grams per kilogram (1.1 grams per pound) of protein intake resulted in muscle gains, even in a 40% calorie deficit.7
- Murphy et al. (2021) observed that more significant calorie deficits correlated with greater lean mass loss, even when resistance training was performed. However, this study did not establish an exact protein intake threshold to prevent muscle loss. 8
These studies suggest that higher protein intakes improve muscle retention but do not clarify the optimal range for dieting athletes.
Findings from the Recent Research on Protein Intake for Optimal Muscle Preservation
🔹 More Protein Leads to Better Muscle Retention
The study found a linear relationship between protein intake and muscle retention. The more protein consumed (up to a certain point), the less muscle was lost. Researchers concluded that 0.86 grams per pound (1.9 grams per kilogram) of body weight per day is the minimum required for muscle retention.
🔹 Leaner Individuals Need More Protein
If you have a lower body fat percentage, you are at a higher risk of losing muscle during a calorie deficit. This is because your body has fewer fat stores to use as energy, so it relies more on muscle tissue. For individuals with less than 12% body fat (males) or less than 20% body fat (females), the study recommends a higher protein intake—up to 1.45 grams per pound (3.2 grams per kilogram) of body weight per day.
🔹 Energy Deficit Size Did Not Impact Protein Needs
Contrary to expectations, larger calorie deficits did not significantly increase protein needs. Whether participants had a small deficit (300 calories per day) or a large deficit (500+ calories per day), their protein requirements remained the same.
How Much Protein Should You Eat?
- If you are in a calorie deficit but want to maximize muscle retention, aim for at least 1.0 grams per pound (2.3 grams per kilogram) of body weight daily.
- For leaner individuals or those on aggressive fat loss plans, increasing protein intake to 1.2–1.45 grams per pound (2.7–3.2 grams per kilogram) may help prevent muscle breakdown.
References
1 Refalo, M. C., Trexler, E. T. & Helms, E. R. Effect of Dietary Protein on Fat-Free Mass in Energy Restricted, Resistance-Trained Individuals: An Updated Systematic Review With Meta-Regression. Strength & Conditioning Journal (9900).
2 Areta, J. L. et al. Reduced Resting Skeletal Muscle Protein Synthesis Is Rescued by Resistance Exercise and Protein Ingestion Following Short-Term Energy Deficit. Ajp Endocrinology and Metabolism 306, E989-E997 (2014). https://doi.org/10.1152/ajpendo.00590.2013
3 Hector, A. J. et al. Pronounced 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. The Faseb Journal 32, 265-275 (2017). https://doi.org/10.1096/fj.201700158rr
4 Slater, G. J. et al. Is an Energy Surplus Required to Maximize Skeletal Muscle Hypertrophy Associated With Resistance Training. Front Nutr 6, 131 (2019). https://doi.org/10.3389/fnut.2019.00131
5 Helms, E. R., Aragon, A. A. & Fitschen, P. J. Evidence-based recommendations for natural bodybuilding contest preparation: nutrition and supplementation. Journal of the International Society of Sports Nutrition 11, 20 (2014). https://doi.org/10.1186/1550-2783-11-20
6 Pasiakos, S. M. et al. Effects of high-protein diets on fat-free mass and muscle protein synthesis following weight loss: a randomized controlled trial. The FASEB Journal 27, 3837-3847 (2013). https://doi.org/https://doi.org/10.1096/fj.13-230227
7 Longland, T. M., Oikawa, S. Y., Mitchell, C. J., Devries, M. C. & Phillips, S. M. Higher compared with lower dietary protein during an energy deficit combined with intense exercise promotes greater lean mass gain and fat mass loss: a randomized trial. Am J Clin Nutr 103, 738-746 (2016). https://doi.org/10.3945/ajcn.115.119339
8 Murphy, C. & Koehler, K. Energy deficiency impairs resistance training gains in lean mass but not strength: A meta-analysis and meta-regression. Scand J Med Sci Sports 32, 125-137 (2022). https://doi.org/10.1111/sms.14075
