Calories and Muscle Growth: Gain Muscle in One Area, Lose in Another

Calories and Muscle Growth: Gain Muscle in One Area, Lose in Another Summary

• The relationship between calories and muscle growth was evident: Higher daily protein and calorie intake were linked to greater muscle growth and less muscle atrophy.
• Muscles not directly trained, like the adductor magnus and soleus, experienced significant atrophy when not engaged in the training.
• The body reallocates energy from non-recruited to recruited muscles, emphasizing the need for a caloric surplus to support overall muscle growth.

Calories and Muscle Growth: Unlocking the Secret to Optimal Muscle Gain

Many experts have discussed the roles of calories and muscle growth. Some have suggested that a big calorie surplus is not necessary to enhance muscle growth. However, the newest study titled Evidence for Simultaneous Muscle Atrophy and Hypertrophy in Response to Resistance Training in Humans by Van Vossel et al. (2024) suggests that a calorie surplus may be necessary for muscle growth.¹ This study found positive correlations between daily protein intake and net muscle growth, as well as between daily energy intake and changes in non-recruited muscle (i.e., Non-recruited muscles are those that are not directly engaged or used during a specific exercise.)  The new study found that muscles that are trained directly increase in size, whereas muscles that are not directly trained experience muscle atrophy.

Calories and Muscle Growth: Review of the Literature

Muscle growth, or hypertrophy, is a complex process influenced by various factors, including calories and muscle growth, exercise, and genetics. Many studies have examined the relationship between protein intake, caloric surplus, and muscle hypertrophy. For instance, Morton et al. (2018) conducted a meta-analysis indicating that higher protein intakes are associated with greater gains in muscle mass and strength during resistance training.² Similarly, a study by Phillips et al. (2017) highlighted the importance of protein quality and distribution throughout the day to maximize muscle protein synthesis.³

Moreover, This is consistent with the findings of (Phillips & Loon, 2011), which stress the role of dietary protein in supporting muscle protein synthesis, a critical aspect of muscle growth in resistance-trained athletes.⁴ In terms of specific calorie intake, research by Helms et al. (2014) recommended a moderate calorie surplus of approximately 10-20% above maintenance levels to support calories and muscle growth while minimizing fat gain.⁵ This is echoed by more recent findings from Iraki et al. (2019), who suggested that a strategic caloric surplus combined with adequate protein intake can enhance muscle hypertrophy.⁶

Overview of the Study Protocol

The study by Van Vossel et al. (2024) explored the simultaneous occurrence of muscle atrophy and hypertrophy in response to resistance training. The study involved 21 untrained individuals (10 females and 11 males) who underwent a 10-week resistance training protocol. Participants performed exercises targeting both upper and lower body muscles, including biceps curls, triceps extensions, leg curls, and leg extensions.

Each participant trained one arm and leg three times per week and the contralateral limbs twice per week. The training regimen consisted of three to four sets per exercise, performed to failure with 60% of one-repetition maximum (1RM), with two minutes of rest between sets and three minutes between exercises. Muscle volume changes were assessed using whole-body MRI scans, focusing on the upper arms and 28 muscles of the lower limbs.

Results

The study yielded several noteworthy findings:

Muscle Hypertrophy: Significant increases in muscle growth were observed in all primary and secondary recruited muscles. (i.e., muscle trained and indirectly trained), while non-recruited muscles showed no hypertrophy, and some experienced significant atrophy.

Primary Recruited Muscles:

Biceps Brachii: Targeted by biceps curls.

Triceps Brachii: Targeted by triceps extensions.

Quadriceps: Targeted by leg extensions.

Hamstrings: Targeted by leg curls.

 Secondary Recruited Muscles:

Brachialis: Engaged during biceps curls.

Brachioradialis: Engaged during biceps curls.

Anconeus: Assists during triceps extensions.

Adductors: Stabilize during leg curls and leg extensions.

Gluteus Maximus: Stabilizes and assists during leg extensions and leg curls.

Muscle Atrophy: Two non-recruited muscles, the adductor magnus (i.e., This muscle is located in the inner thigh and helps bring the legs together.) and soleus (i.e., This muscle is found in the lower leg and helps with pushing off the ground when walking or running.), experienced significant atrophy or loss of muscle size.

Calories and Muscle Growth: Nutritional Impact:

The study found two important connections related to nutrition and muscle growth:

Protein and Muscle Growth: Eating more protein each day was linked to greater overall muscle growth.

Calories and Muscle Maintenance: Consuming more calories daily helped prevent the muscles that weren’t directly exercised from shrinking.

Discussion

One of the key takeaways from the study is the importance of training all muscle groups while dieting. The research suggests that preventing muscle atrophy in untrained muscles can contribute to overall energy balance and support muscle gain in the muscles that are being actively trained. The study by Van Vossel et al. (2024) provides compelling evidence that both protein and caloric intake play crucial roles in calories and muscle growth. The observed muscle atrophy in non-recruited muscles (i.e., muscles not directly trained) suggests that the body may reallocate resources (i.e., steal from other body parts) to support hypertrophy in trained muscles, especially when nutritional intake is suboptimal.

The positive relationship between daily protein intake and muscle growth reinforces the importance of protein for muscle repair and synthesis. Moreover, the significant relationship between total calories and loss of muscle mass in muscle not being directly trained emphasizes the necessity of a caloric surplus for optimal muscle growth. These findings challenge the notion that muscle hypertrophy can be achieved without a caloric surplus. Instead, they suggest that adequate energy intake is essential to support the metabolic demands of muscle growth while preventing atrophy in untrained muscles.

Practical Applications for Calories and Muscle Growth

For fitness enthusiasts and bodybuilders, the practical applications of this study are clear:

Ensure Adequate Protein Intake: Aim for a daily protein intake that supports muscle repair and muscle gains. Studies suggest consuming 1.6-2.2 grams of protein per kilogram of body weight.

Maintain a Caloric Surplus: To maximize calories and muscle growth, maintain a moderate caloric surplus of approximately 10-20% above maintenance levels. This provides the necessary energy for muscle repair and growth.

Train All Muscle Groups: Even when targeting specific muscles for hypertrophy, include exercises that engage all muscle groups to prevent atrophy and promote balanced muscle development.

Monitor Nutritional Intake: Pay attention to both macronutrient composition and overall caloric intake. Ensure that your diet supports your training goals and provides sufficient energy and nutrients.

 References

1               Van Vossel, K. et al. Evidence for Simultaneous Muscle Atrophy and Hypertrophy in Response to Resistance Training in Humans. Med Sci Sports Exerc (2024). https://doi.org:10.1249/mss.0000000000003475

2               Morton, R. W. et al. A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength in healthy adults. Br J Sports Med 52, 376-384 (2018). https://doi.org:10.1136/bjsports-2017-097608

3               Phillips, S. M., Chevalier, S. & Leidy, H. J. Protein “requirements” beyond the RDA: implications for optimizing health. Appl Physiol Nutr Metab 41, 565-572 (2016). https://doi.org:10.1139/apnm-2015-0550

4               Phillips, S. M. & Loon, L. J. C. v. Dietary Protein for Athletes: From Requirements to Optimum Adaptation. Journal of Sports Sciences 29, S29-S38 (2011). https://doi.org:10.1080/02640414.2011.619204

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               Iraki, J., Fitschen, P., Espinar, S. & Helms, E. Nutrition Recommendations for Bodybuilders in the Off-Season: A Narrative Review. Sports (Basel) 7 (2019). https://doi.org:10.3390/sports7070154