Omega-3 Fatty Acids and Muscle Growth: What the Science Says

If you spend any time in fitness circles, you've probably heard someone extol the benefits of fish oil. Traditionally, the conversation centers around heart health, joint inflammation, and brain function. But here's a question that doesn't get asked enough: Can omega-3 fatty acids actually help you build muscle?

It's a fair question. The research has been mixed, and the fitness supplement industry has a habit of extrapolating wild claims from thin evidence. So let's dig into what the science actually shows—particularly the 2024 and 2025 meta-analyses that have tried to bring some clarity to this debate.

The Biological Case for Omega-3s

Before we get into the human data, let's talk mechanism. Omega-3 fatty acids—primarily EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid)—are incorporated into cell membrane phospholipids. This matters for muscle because:

• mTOR Activation: Some research suggests omega-3s may support the mTOR signaling pathway, which is essentially the "on switch" for muscle protein synthesis.

• Anti-Inflammatory Effects: Resistance training creates muscle damage and inflammation. Omega-3s can modulate the inflammatory response, potentially reducing delayed onset muscle soreness (DOMS) and improving recovery.

• Satellite Cell Function: Omega-3s may support satellite cells—the muscle stem cells responsible for repair and growth. Animal studies have shown promising results here, though human evidence is thinner.

• Muscle Protein Synthesis: Some studies suggest omega-3s can increase the sensitivity of muscle tissue to amino acids, making your protein intake more effective.

What the 2024-2025 Research Shows

A 2024 meta-analysis published in Clinical Nutrition ESPEN by Uchida et al. reviewed randomized controlled trials examining omega-3 supplementation combined with resistance training. The findings were interesting:

• Muscle Strength: Omega-3 supplementation + resistance training significantly improved muscle strength compared to placebo + resistance training
• Muscle Mass: No significant effects were observed for muscle mass specifically

The researchers noted this combination "shows promise as a countermeasure against muscular dysfunction" and holds implications for maintaining quality of life, particularly in older adults.

Another 2025 review in Nutrition Reviews examined omega-3 effects across multiple studies, noting that doses above 2g/day may contribute to muscle mass gains (around 0.67 kg) and improve walking speed in older populations.

The Nuance You Need to Understand

Here's where honest interpretation matters:

The strength benefits appear real, but they're not magic. We're not talking about transformative changes—we're talking about modest improvements that might accelerate your progress by a few percentage points. The muscle mass findings are less consistent. Some studies show nothing. Others show small gains, particularly in older adults or untrained individuals. If you're already several years into serious training, don't expect omega-3s to magically add inches to your arms. Dosing matters. The research that shows benefits typically uses 2-3+ grams of combined EPA/DHA daily. That's more than most standard fish oil softgels provide. You'd need to either take many capsules or spring for a concentrated fish oil. Training status matters. The biggest benefits seem to appear in:

• Older adults (counteracting age-related muscle loss)
• Untrained individuals (anyone new to resistance training)
• People with inflammatory conditions

Practical Recommendations

Based on the current evidence, here's what makes sense:

• Don't rely on omega-3s for muscle growth. Treat them as a potential辅助—something that might nudge the needle slightly, not a primary driver of gains.

• Prioritize the basics first. Adequate protein (1.6-2.2g/kg), progressive overload, sufficient sleep, and proper training volume matter far more than supplementation.

• If you do supplement, dose properly. Aim for 2-3g of combined EPA/DHA daily. Standard fish oil often has less, so check labels or consider concentrated forms.

• Consider the other benefits. Even if the muscle-building effects are modest, omega-3s support heart health, brain function, and may reduce inflammation. That's not nothing.

• Get them from food when possible. Fatty fish like salmon, mackerel, and sardines provide omega-3s along with quality protein and other nutrients. Eat fish 2-3 times weekly and you may not need supplements at all.

The Bottom Line

Omega-3 fatty acids aren't a shortcut to bigger muscles. The 2024-2025 research shows they may provide a modest edge in strength when combined with resistance training, particularly for older adults or those just starting out. But they're not going to transform your physique on their own.

Think of them as one piece of a larger puzzle—potentially helpful, certainly not harmful for most people, but nowhere near as important as nailing the fundamentals of training and nutrition.

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References

• Uchida Y, et al. Effects of Omega-3 fatty acids supplementation and resistance training on skeletal muscle. Clin Nutr ESPEN. 2024;61:189-196.

• Effects of omega-3 polyunsaturated fatty acids on muscle and whole-body protein synthesis. Nutrition Reviews. 2025;83(2):e131.

• Effects of Omega-3 Fatty Acids on Muscle Mass, Muscle Strength and Muscle Performance among the Elderly: A Meta-Analysis. PubMed. 2020;33291698.

• Omega-3 supplementation combined with strength training on neuro-biomarkers and inflammatory responses. PMC. 2025.