Curious about fish oil’s impact on metabolism? Studies show it can boost resting metabolic rate, fat oxidation, and lean mass. Here’s what you need to know.

Key takeaways

• Fish oil increases resting metabolic rate, helping burn more calories at rest.
• Omega-3s enhance fat oxidation, making the body more efficient at using fat for energy.
• Supplementing with fish oil supports lean muscle growth and overall body composition.
• EPA and DHA reduce inflammation, improving metabolic function and cardiovascular health.

Introduction

Fish oil supplements are widely known for their brain and mood benefits, but emerging research suggests they may also play a significant role in enhancing metabolic health. 

Recent studies have highlighted improvements in resting metabolic rate (RMR), energy expenditure, fat oxidation, and even lean mass, making fish oil an attractive option for those seeking to optimise body composition and overall metabolic health.

In this article, we explore the science behind fish oil’s metabolic benefits, the key components that drive these effects, and practical advice on how to choose and incorporate these supplements into your daily routine. We also discuss additional health benefits and considerations, providing you with a comprehensive resource for making informed decisions about fish oil supplementation.

What are fish oil supplements?

Fish oil is derived from the tissues of oily fish such as salmon, mackerel, sardines, and anchovies. These supplements are rich in omega-3 fatty acids, which are essential fats that the body cannot produce on its own. Omega-3s play crucial roles in cell membrane function, inflammation regulation, and overall cardiovascular and brain health.

Fish oil supplements are available in various forms, including capsules, liquids, and emulsions. They are popular among those looking to support cognitive function, heart health, joint mobility, and more recently, metabolic performance.

The benefits of fish oil on metabolism and body composition extend beyond the findings of a single study. Here are several ways in which these supplements may influence your metabolic health:

Key components: EPA and DHA

The primary omega-3 fatty acids found in fish oil are eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Each plays a unique role in the body:

EPA (Eicosapentaenoic Acid)

• Known for its anti-inflammatory properties.
• Supports cardiovascular health by helping to maintain healthy blood lipid levels.
• May influence fat metabolism and energy expenditure.

DHA (Docosahexaenoic Acid)

• A major structural component of the brain and retina.
• Crucial for cognitive function and mood regulation.
• Supports the integrity of cell membranes, contributing to overall cellular health.

The synergy between EPA and DHA is thought to underpin many of the health benefits associated with fish oil, including its potential to improve metabolic rate and body composition.

The science behind fish oil and etabolic health

One notable study from 2015 focused on the metabolic effects of fish oil in older women. In this study, 24 women aged around 66 years were divided into two groups. One group received 3 grams per day of fish oil (providing 2 grams of EPA and 1 gram of DHA), while the other group was given olive oil as a placebo. Both groups consumed identical calorie amounts to control for dietary differences.

After 12 weeks, the group taking fish oil supplements experienced remarkable improvements in several key metabolic markers:

Increase your Resting Metabolic Rate (RMR) by 14%

A higher RMR indicates that the body burns more calories at rest, which can aid in weight management.

Approximately 10% increase in energy expenditure during exercise

Enhanced energy expenditure during physical activity suggests improved exercise performance and endurance.

Increased fat oxidation

• 19% higher fat oxidation at rest.
• 27% higher fat oxidation during activity.

This means that the body becomes more efficient at burning fat for fuel.

Increase in lean mass

Lean body mass increased by 4% (from 40.3 kg to 41.9 kg), representing a 1.6 kg absolute increase.

Additionally, improvements in cardiovascular fitness were observed:

VO₂ max improvement

The fish oil group saw an increase in VO₂ max (a measure of aerobic fitness), while the placebo group experienced no change.

Reduction in resting heart rate

A drop of approximately 3 beats per minute (bpm) was noted in the fish oil group, which can be an indicator of improved heart health.

These findings, which remained significant even after adjusting for changes in body mass and lean mass, provide compelling evidence that fish oil supplementation can positively influence metabolic health.

Wondering how to time your workouts for the best metabolic health benefits? Discover the science behind optimising exercise timing in this guide and learn how it can impact your blood sugar and overall well-being.

Understanding the mechanisms

The metabolic improvements observed in the study may be attributed to several mechanisms:

Enhanced fat oxidation

Fish oil appears to stimulate the enzymes responsible for breaking down fatty acids, leading to increased fat burning both at rest and during exercise.

Mitochondrial function

Omega-3 fatty acids may improve the efficiency of mitochondria—the powerhouses of the cell—resulting in a higher resting metabolic rate.

Anti-inflammatory effects

By reducing systemic inflammation, fish oil can improve insulin sensitivity and metabolic function. Chronic inflammation is known to impair metabolic processes and contribute to fat accumulation.

Improved cardiovascular function

The observed improvements in VO₂ max and resting heart rate suggest that fish oil may enhance cardiovascular efficiency, which in turn supports better oxygen and nutrient delivery to tissues during exercise.

How fish oil might improve metabolic rate and body composition

The benefits of fish oil on metabolism and body composition extend beyond the findings of a single study. Here are several ways in which these supplements may influence your metabolic health:

1. Boosting Resting Metabolic Rate (RMR)

• Increased calorie burn: A higher RMR means your body burns more calories even when at rest. This is crucial for maintaining a healthy weight.
• Enhanced fat oxidation: More efficient fat burning can help reduce body fat percentage over time.

2. Supporting lean muscle mass

• Muscle growth: Fish oil has been associated with increased lean mass, which is important because muscle tissue burns more calories than fat tissue.
• Improved recovery: The anti-inflammatory properties of omega-3s can aid in muscle recovery following exercise, potentially leading to better gains over time.

3. Enhancing exercise performance

• Increased energy expenditure: Studies suggest that fish oil can raise the number of calories burned during physical activity, which may enhance overall exercise performance.
• Cardiovascular benefits: Improved VO₂ max and a lower resting heart rate indicate that fish oil supports cardiovascular efficiency, enabling more effective workouts.

4. Regulating appetite and metabolic hormones

• Some research indicates that omega-3 fatty acids can help regulate hormones related to appetite and metabolism, such as insulin and leptin, which play roles in energy balance and fat storage.

By addressing multiple aspects of metabolism—from energy expenditure to muscle growth—fish oil supplements represent an evidence-based strategy to improve body composition and overall metabolic health.

Additional health benefits of fish oil supplements

While the metabolic advantages of fish oil are compelling, these supplements offer a range of other benefits that contribute to overall wellbeing:

Cardiovascular health

Omega-3s help reduce triglyceride levels, lower blood pressure, and prevent the formation of arterial plaque, all of which support heart health. Research from reputable organisations such as the American Heart Association has long promoted the heart-protective effects of fish oil.

Cognitive function and mood

DHA is a critical component of brain tissue, and its presence is essential for maintaining cognitive function and mental clarity. Studies have also linked fish oil supplementation with reduced symptoms of depression and anxiety.

Anti-inflammatory properties

Chronic inflammation is a root cause of many health conditions, including arthritis and metabolic syndrome. The anti-inflammatory effects of fish oil can help mitigate these issues.

Joint and bone health

By reducing inflammation, fish oil may help alleviate joint pain and improve overall joint mobility, making it a popular supplement among those with arthritis or joint discomfort.

Skin and eye health

Omega-3 fatty acids contribute to the maintenance of healthy skin and eyes by supporting cell membrane integrity and reducing inflammation.

The broad spectrum of benefits makes fish oil an attractive supplement for individuals looking to support multiple aspects of their health through a single, evidence-backed nutritional intervention.

How to choose the right fish oil supplement

When selecting a fish oil supplement, several factors should be considered to ensure you receive the highest quality product:

1. Purity and auality

• Third-party testing: Choose products that have been independently tested for purity and contaminants such as heavy metals, PCBs, and dioxins. Look for certifications from recognised testing organisations.
• Source of fish: Fish from cold-water species like salmon, mackerel, and sardines are typically higher in omega-3 content. Ensure that the supplement is derived from sustainable sources.

2. EPA and DHA content

• Label transparency: Check the label to confirm the amounts of EPA and DHA per serving. The study discussed earlier used a ratio of 2:1 (EPA:DHA) with a total of 3 grams per day.
• Dosage recommendations: While dosages vary depending on individual health goals, many studies have used between 1–3 grams of combined EPA and DHA per day. Adjust your intake based on your dietary habits and health objectives.

3. Formulation and delivery

• Capsules vs liquid: Fish oil is available in both capsule and liquid forms. Capsules offer convenience and reduce the likelihood of fishy aftertastes, while liquid forms may be more cost-effective and allow for easier dosage adjustments.
• Enteric coating: Some supplements come with an enteric coating to minimise gastrointestinal discomfort and prevent the fishy burps that some users experience.

4. Storage and stability

• Oxidation prevention: Fish oil can oxidise and lose its potency if not stored properly. Look for products that include natural antioxidants such as vitamin E, and always store your supplements in a cool, dark place.

By paying attention to these factors, you can choose a fish oil supplement that not only meets your nutritional needs but also supports your overall health goals.

Best fish oil supplements in Australia: top brands compared

If you’re looking for a high-quality fish oil supplement, Australia has several well-known brands that offer trusted and effective options. Below, we compare some of the most popular fish oil supplements, including Blackmores, BioCeuticals, Swisse, Nature’s Way, and Chemist Warehouse’s own brand.

1. Blackmores Fish Oil

• Brand reputation: One of Australia’s most well-known health supplement brands.
• Omega-3 content: Standard Blackmores Fish Oil contains 300 mg of EPA & DHA per capsule. They also offer a 1000 mg version with higher potency.
• Sustainability: Sourced from small fish (like anchovies and sardines) and tested for mercury.
• Price range: Mid-range, widely available at supermarkets and pharmacies.
• Best for: Those looking for a reliable, widely available, and well-tested fish oil supplement.

2. BioCeuticals UltraClean Omega-3

• Brand reputation: A premium, practitioner-only brand that focuses on high-quality, therapeutic supplements.
• Omega-3 content: Highly concentrated with 300 mg of EPA and 200 mg of DHA per capsule.
• Purity: Third-party tested for heavy metals and toxins.
• Price range: More expensive than supermarket brands but higher quality.
• Best for: Those wanting a high-dose, premium fish oil supplement with clinical-grade purity.

3. Swisse Ultiboost Odourless Fish Oil

• Brand reputation: One of Australia’s most recognisable supplement brands.
• Omega-3 content: 300 mg EPA & DHA per capsule (like Blackmores).
• Odourless formula: Reduces fishy aftertaste and burps.
• Sustainability: Certified sustainable and sourced from wild fish.
• Price range: Affordable, widely available at supermarkets and pharmacies.
• Best for: People looking for an affordable, easy-to-find fish oil that doesn’t cause fishy burps.

4. Nature’s Way Fish Oil

• Brand reputation: Popular for affordable vitamins and supplements.
• Omega-3 content: Around 180 mg EPA & 120 mg DHA per capsule (lower than some premium brands).
• Sustainability: Wild fish sourced, but less transparent about purity testing.
• Price range: One of the cheapest options, often available in bulk packs.
• Best for: Budget-conscious buyers who want a basic fish oil supplement.

5. Chemist Warehouse Own Brand (Healthy Care Fish Oil)

• Brand reputation: Sold under Chemist Warehouse’s Healthy Care label, offering competitive pricing.
• Omega-3 content: 300 mg EPA & DHA per capsule (similar to Blackmores and Swisse).
• Purity & sustainability: Meets Australian standards but not always third-party tested.
• Price range: One of the most affordable fish oil supplements in Australia.‍
• Best for: Bargain shoppers looking for a solid fish oil supplement at a low price.

Which fish oil supplement should you choose?

The best fish oil supplement depends on your health goals, budget, and quality preferences. Here’s a quick guide:

If you’re looking for higher EPA and DHA content, go for BioCeuticals or Blackmores Omega Triple Strength. If affordability is your priority, Healthy Care or Nature’s Way are great options.

Regardless of which brand you choose, consistency matters more than anything—taking your fish oil daily is what leads to results!

How to incorporate fish oil into your daily routine

Integrating fish oil supplements into your daily routine can be straightforward with a few simple strategies:

1. Pair with meals

Take your fish oil supplement with a meal that contains healthy fats. This enhances absorption and reduces the chance of digestive discomfort.

2. Consistency is key

Establish a regular schedule to take your supplement—whether it’s in the morning with breakfast or in the evening with dinner—to ensure you receive a steady supply of omega-3 fatty acids.

3. Combine with a balanced diet

While fish oil offers numerous benefits on its own, pairing it with a nutrient-rich diet that includes fruits, vegetables, lean proteins, and whole grains maximises its positive effects on metabolism and overall health.

4. Monitor your progress

Track changes in your energy levels, exercise performance, and body composition. This can help you assess whether your current dosage and routine are effective, and allow you to adjust as needed.

5. Consult reliable resources

Stay updated with the latest research and expert advice on fish oil supplementation. Credible sources such as peer-reviewed studies and health organisation websites provide ongoing insights into best practices.

6. Potential side effects and considerations

While fish oil supplements are generally well tolerated, it’s important to be aware of potential side effects and considerations:

7. Digestive issues

Some users may experience mild gastrointestinal discomfort, such as bloating or diarrhoea. Taking fish oil with food can help minimise these effects.

8. Fishy aftertaste

A common complaint is a fishy aftertaste or burps. Opting for enteric-coated capsules or high-quality products with refined processing can help reduce this issue.

9. Blood thinning effects

Omega-3s have blood-thinning properties. If you are on blood-thinning medications or have a bleeding disorder, monitor your intake carefully and consult with a healthcare provider if necessary.

10. Allergies

Individuals with fish or shellfish allergies should exercise caution and consider plant-based omega-3 alternatives, such as algae oil, which also provide DHA and EPA.

11. Quality variations

Not all fish oil supplements are created equal. Variability in manufacturing processes and sourcing can affect the quality and potency of the product. Always opt for brands with transparent labelling and third-party testing.

By understanding these potential side effects and taking appropriate precautions, you can safely enjoy the benefits of fish oil supplements while minimising any unwanted reactions.

Curious about how to align your meals and workouts for better metabolic health? Learn how a CGM can help you optimise nutrition and exercise timing in optimising nutrition and exercise timing with a CGM for improved energy and blood sugar control.

Integrating fish oil into a holistic health strategy

Fish oil supplements offer an evidence-based strategy for enhancing metabolic performance, but they work best when integrated into a comprehensive approach to health. Here are some additional strategies to consider:

Regular physical activity

Exercise naturally boosts your metabolic rate and enhances fat oxidation. Combining physical activity with fish oil supplementation may further improve your body composition and cardiovascular fitness.

Balanced nutrition

Support your metabolic health with a balanced diet that includes a variety of nutrient-dense foods. Omega-3-rich foods like fatty fish, walnuts, and flaxseeds can complement your supplementation strategy.

Sleep and stress management

Adequate sleep and effective stress management are crucial for maintaining a healthy metabolism. Poor sleep and chronic stress can negatively impact hormonal balance, making it harder for your body to regulate weight and energy expenditure.

Want to take control of your hormonal health? Discover how CGMs can support balanced hormones and overall well-being in Vively’s hormone health program.

Regular monitoring

Keep track of your progress by monitoring changes in your energy levels, exercise performance, and body composition. Journaling your experiences or using fitness tracking apps can provide valuable insights and help you adjust your regimen as needed.

By combining fish oil supplementation with these lifestyle practices, you create a robust foundation for sustained metabolic health and overall wellbeing.

Ever wondered how a Continuous Glucose Monitor (CGM) can enhance your metabolic health? Find out in our blog on 7 ways CGM can improve your metabolic health.

Conclusion

Fish oil supplements, long celebrated for their cognitive and cardiovascular benefits, are now gaining recognition for their ability to enhance metabolic rate and improve body composition. The evidence—such as the 2015 study on older women—demonstrates that regular fish oil intake can lead to a 14% increase in resting metabolic rate, higher energy expenditure during exercise, improved fat oxidation, and an increase in lean mass.

These improvements, alongside enhanced cardiovascular markers like VO₂ max and reduced resting heart rate, highlight the potential of fish oil as a multifaceted supplement for those seeking to optimise their health.

When selecting a fish oil supplement, consider factors such as purity, EPA/DHA content, formulation, and storage guidelines to ensure you’re choosing a product that meets your needs. Integrating fish oil into a holistic health strategy that includes regular exercise, balanced nutrition, and proper sleep can further amplify its benefits, supporting not just metabolic health but overall quality of life.

As research continues to uncover the diverse benefits of omega-3 fatty acids, incorporating fish oil into your daily routine offers a practical, evidence-based approach to achieving better metabolic performance and enhanced body composition. Whether you’re looking to manage your weight, boost exercise performance, or support long-term health, fish oil supplements represent a valuable addition to your health regimen.

For those interested in exploring further, the study on fish oil and metabolic health can be accessed through PubMed Central and PubMed. Additionally, reputable health organisations provide ongoing updates on omega-3 research, helping you stay informed about the latest developments in nutritional science.

By embracing the power of fish oil supplements, you can take proactive steps toward a healthier metabolism, improved body composition, and overall enhanced wellbeing. Enjoy the journey of optimising your health—one supplement at a time.

Vively is a metabolic health app that can help women undergoing the menopause transition improve their quality of life. The Vively app integrates with continuous glucose monitors (CGM) to help women understand how their lifestyle is impacting their blood sugar levels. This, combined with in-app education and support can help women improve their symptoms. Chat to your doctor about whether Vively may suit you.

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References

• Fish Oil Supplementation Increases Resting Metabolic Rate and Improves Body Composition in Older Women (PubMed Central)

• Study Abstract on Fish Oil and Metabolic Health (PubMed)

• American Heart Association – Omega-3 Fatty Acids

• Harvard Health – The Benefits of Omega-3 Fatty Acids

By understanding the science, selecting high-quality supplements, and integrating them into a balanced lifestyle, you can harness the full potential of fish oil to boost your metabolic health and enhance your overall quality of life.