Supplementing with Omega-3 fish oil has been shown to be very effective at reducing blood triglyceride levels, which is basically the level of fat in the blood, and is a major risk factor for heart disease. Fish oil has been approved as a treatment by the FDA for high triglycerides since 2004, and in people with very high triglyceride levels, (i.e above 500 mg/dl), taking 4g of fish oil per day can reduce triglyceride levels by 45% and LDL (aka the ‘bad cholesterol’) by more than 50% . In this article, we are going to discuss the benefits of taking fish oil for fat loss.
However, as well as reducing fat in the blood, omega-3 also seems to be very effective in helping fat loss on the body as well.
Studies into the effect of omega-3 on fat loss were initially conducted in animals in the ’80s and ’90s and showed that fish oil supplementation could reduce weight and cause fat loss in terms of a reduction of body fat %, a reduction in body weight, and a reduction in the size and number of fat cells 3-12].
Interestingly, in the experiments it didn’t seem to matter whether calories were reduced, kept at the same level, or even increased, simply adding fish oil to the diet resulted in reductions in body fat and weight!
Ok, But That’s Animals, What About Humans?
After the results from the animal studies, researchers went on to see if the fish oil weight loss results could be replicated in humans.
The studies looked at the effect of supplementing with fish oil in different scenarios which included:
- not changing participants’ lifestyle in any other way apart from adding fish oil supplementation
- adding fish oil plus an exercise program
- adding fish oil plus reducing calorie intake
- and adding fish oil plus an exercise program and reducing calories.
Several studies have shown that fish oil supplementation alone with no other changes in diet, lifestyle or exercise increases fat burning and decreases body fat percentage.
1st Study About Fish Oil and Weight Loss – Young Men
The first study focused on healthy young men who supplemented with 6 grams of fish oil per day (although it was 6 grams of fish oil it actually only contained 1100mg of EPA and 700mg of DHA) . The results indicated a statistically significant weight reduction. Another paper based on the same study found that fish oil supplementation also reduced insulin levels and increased fat burning after eating carbohydrate-rich meals .
2nd Study About Fish Oil and Weight Loss – Women With Type 2 Diabetes
The second study focused on women with type 2 diabetes, with the subjects taking 3 grams of fish oil per day, (1,080 mg EPA and 720 mg DHA) for 2 months. They also found an increase in fat burning, with the women losing an average of 3.6lbs (1.6 kg) over the 2 month period. The researchers also found there was a reduction in triglycerides and an increase in HDL (aka the ‘good cholesterol’) as well .
3rd Study About Fish Oil and Weight Loss – The Effect of Omega-3 on Muscle Mass
A third study actually looked at the effect of omega-3 fish oil on lean muscle mass (i.e muscle loss or gain), it found that when participants did not change their diet or lifestyle in any other way, supplementing with fish oil over a 6 week period led to an 0.5 kg (1.1lb) reduction in body fat, and a 0.5kg (1.1lb) increase in muscle mass with no overall change in body weight. . Fat loss and muscle gain, it doesn’t get much better or healthier than that!
Fish Oil, Exercise and Traditional Dieting
However, although these 3 studies have shown that fish oil on its own can cause fat loss, we always recommend that supplements should be part of an overall solution to improving health including lifestyle and dietary changes, which will always lead to the best possible results.
For example, one study found that supplementation with fish oil providing 2,400 mg EPA and 1,600 mg DHA for 3 weeks, significantly increased the body’s ability to use and burn fat for energy when running at 60% of VO2 max. This means that omega-3 fish oil supplementation can make people more efficient burners of fat when they are exercising .
Another study on obese men and women who supplemented with 6 g of fish oil daily, (360 mg EPA and 1,560 mg DHA), for 12 weeks with light exercise, (75% of max heart rate aerobic exercise), found that fish oil and exercise resulted in a significant loss of body fat (4.4 lb, 2 kg), as well as improvements in heart disease risk factors, and a reduction in triglycerides, and an increase in HDL over just exercise alone .
A further study on 324 men and women from ages 20 – 40, found that when they reduced calorie intake by 30%, an average of 600 calories per day, those who supplemented with fish oil lost on average 1kg (2.2lbs) moreover a 4 week period than those that just reduced calories .
A study conducted on severely obese women also found that exercise and fish oil resulted in 1.5kg (3.3lbs) more weight loss in those supplementing with fish oil than those who didn’t. The researchers also found greater levels of blood beta-hydroxybutyrate in the fish oil supplemented group. Beta-hydroxybutyrate is a ketone body, so the results also suggest that fish oil supplementation can also stimulate greater levels of ketosis, which is effectively more efficient fat burning .
So How Does Fish Oil Help With Fat Loss?
Omega-3 can literally change our genes. For a long time it was thought that our genes were set in stone and couldn’t be changed, and whilst our DNA code itself doesn’t change, we now know that how our genes are expressed can and does change. In other words, our cells can turn certain genes ‘on’ or ‘off’ depending on the environment they are exposed to . The new branch of science that studies this is known as epigenetics and will bring huge developments to our understanding of our bodies and how we think about health in the future.
By regulating and downregulating genes, omega-3 fatty acids act as fuel partitioners, basically changing the actions of enzymes to make less fat, as well as burning more fat. They direct glucose towards glycogen storage, (so it becomes a readily available source of energy), and direct fatty acids away from being turned in triglycerides and towards oxidation. In other words, they make us more efficient fat burners. They also enhance thermogenesis which is an increase in the body’s production of heat, which also results in more of the calories we eat being burned for energy   .
Another way Omega-3 fatty acids work to reduce fat-storage is by increasing levels of the hormone adiponectin in the blood [31-33]. Adiponectin increases insulin sensitivity, lowers blood sugar and triglyceride levels, is anti-inflammatory and stimulates fatty acid oxidation . Generally speaking, the higher levels of adiponectin the less body fat a person has. Omega-3 also reduces cortisol levels  . increased cortisol levels cause us to feel more stressed and can cause obesity and excess fat storage  .
Conclusion: do you need fish oil for fat loss?
Omega-3 can and should be a part of any fat or weight loss program, as well as for anyone who wants to maintain maximum health. Some studies have shown that it can have fat-burning properties independent of any changes in diet or lifestyle. However, we need to be realistic, anytime we want to make changes we need to take a holistic view, i.e looking at everything related to weight gain rather than expecting a ‘magic pill’ to make everything better. Ultimately, when we do this the results are better and much more likely to be permanent.
Current studies into fat loss have varied in the amount of fish oil supplementation used, from 1800mg of omega-3 up to 4000mg. However, these studies have been conducted with the less well absorbed and effective ethyl ester form of fish oil. At Intelligent Labs, we only sell omega-3 in the natural triglyceride form which is better absorbed, more effective in the body, and generally better tolerated. We recommended a daily fat or weight loss dosage of 2250mg of our omega-3 fish oil, but for those trying to lose a significant amount of fat may want to try taking more, ensuring any increase in dosage is well tolerated, or as directed by your medical professional.
 McKenney JM, Sica D. Role of prescription omega-3 fatty acids in the treatment of hypertriglyceridemia. Pharmacotherapy. 2007 May;27(5):715-28. https://www.ncbi.nlm.nih.gov/pubmed/17461707
 Bays HE, Tighe AP, Sadovsky R, Davidson MH. Prescription omega-3 fatty acids and their lipid effects: physiologic mechanisms of action and clinical implications. Expert Rev Cardiovasc Ther. 2008 Mar;6(3):391-409. doi: 10.1586/14779072.6.3.391. https://www.medscape.com/viewarticle/573460_5
 R.A. Baillie, R. Takada, M. Nakamura, S.D. Clarke. Coordinate induction of peroxisomal acyl-CoA oxidase and UCP-3 by dietary fish oil: a mechanism for decreased body fat deposition. Prostaglandins, Leukotrienes and Essential Fatty Acids (PLEFA), 1999, 60, 5-6, 351-356. https://www.ncbi.nlm.nih.gov/pubmed/10471120
 LeBoeuf RC1, Veldee MS. Genetically determined body weight loss in mice fed diets containing salmon oil. J Nutr. 1993 Mar;123(3):547-58. https://www.ncbi.nlm.nih.gov/pubmed/8463856
 Mori T1, Kondo H, Hase T, Tokimitsu I, Murase T. Dietary fish oil upregulates intestinal lipid metabolism and reduces body weight gain in C57BL/6J mice. J Nutr. 2007 Dec;137(12):2629-34. https://academic.oup.com/jn/article/137/12/2629/4670017
 Cunnane SC1, McAdoo KR, Horrobin DF. n-3 Essential fatty acids decrease weight gain in genetically obese mice. Br J Nutr. 1986 Jul;56(1):87-95. https://www.ncbi.nlm.nih.gov/pubmed/3676212
 Hill JO, Peters JC, Lin D, Yakubu F, Greene H, Swift L. Lipid accumulation and body fat distribution is influenced by type of dietary fat fed to rats. Int J Obes Relat Metab Disord. 1993 Apr;17(4):223-36. https://www.semanticscholar.org/paper/Lipid-accumulation-and-body-fat-distribution-is-by-Hill-Peters/37bab106f192c6a49eca6798c86a10741d0c8125
 Su W1, Jones PJ. Dietary fatty acid composition influences energy accretion in rats. J Nutr. 1993 Dec;123(12):2109-14. https://academic.oup.com/jn/article/123/12/2109/4723319
 Pan DA1, Storlien LH. Dietary lipid profile is a determinant of tissue phospholipid fatty acid composition and rate of weight gain in rats. J Nutr. 1993 Mar;123(3):512-9. https://academic.oup.com/jn/article/123/3/512/4723339
 Jana Ruzickova, Martin Rossmeisl, Tomas Prazak, Pavel Flachs, Jana Sponarova, Marek Vecka, Eva Tvrzicka, Morten Bryhn, Jan Kopecky. Omega-3 PUFA of marine origin limit diet-induced obesity in mice by reducing cellularity of adipose tissue. Lipids December 2004, Volume 39, Issue 12, pp 1177-1185 https://www.researchgate.net/publication/246971111_Omega3_PUFA_of_marine_origin_limit_diet-induced_obesity_in_mice_by_reducing_cellularity_of_adipose_tissue
 Parrish CC1, Pathy DA, Angel A. Dietary fish oils limit adipose tissue hypertrophy in rats. Metabolism. 1990 Mar;39(3):217-9. https://www.sciencedirect.com/science/article/abs/pii/002604959090038E
 Belzung F1, Raclot T, Groscolas R. Fish oil n-3 fatty acids selectively limit the hypertrophy of abdominal fat depots in growing rats fed high-fat diets. Am J Physiol. 1993 Jun;264(6 Pt 2):R1111-8. https://www.physiology.org/doi/abs/10.1152/ajpregu.1993.264.6.R1111?journalCode=ajpregu
 Couet C, Delarue J, Ritz P, Antoine JM, Lamisse F. Effect of dietary fish oil on body fat mass and basal fat oxidation in healthy adults. Int J Obes Relat Metab Disord. 1997 Aug;21(8):637-43. https://www.ncbi.nlm.nih.gov/pubmed/15481762
 Delarue J1, Couet C, Cohen R, Bréchot JF, Antoine JM, Lamisse F. Effects of fish oil on metabolic responses to oral fructose and glucose loads in healthy humans. Am J Physiol. 1996 Feb;270(2 Pt 1):E353-62. https://www.physiology.org/doi/abs/10.1152/ajpendo.1996.270.2.E353
 Kabir M, Skurnik G, Naour N, Pechtner V, Meugnier E, Rome S, Quignard-Boulangé A, Vidal H, Slama G, Clément K, Guerre-Millo M, Rizkalla SW. Treatment for 2 mo with n 3 polyunsaturated fatty acids reduces adiposity and some atherogenic factors but does not improve insulin sensitivity in women with type 2 diabetes: a randomized controlled study. Am J Clin Nutr. 2007 Dec;86(6):1670-9. https://academic.oup.com/ajcn/article/86/6/1670/5064836
 Derek M Huffman, Jody L Michaelson, Tom R Thomas, M Derek, Jody L Huffman, Tom R Thomas Michaelson. Chronic supplementation with fish oil increases fat oxidation during exercise in young men. JEPonline, 2004. 7(1): p. 48-56. https://www.researchgate.net/publication/228770868_Chronic_supplementation_with_fish_oil_increases_fat_oxidation_during_exercise_in_young_men
 Hill AM, Buckley JD, Murphy KJ, Howe PR. Combining fish-oil supplements with regular aerobic exercise improves body composition and cardiovascular disease risk factors. Am J Clin Nutr. 2007 May;85(5):1267-74. https://academic.oup.com/ajcn/article/85/5/1267/4633055
 Thorsdottir I, Tomasson H, Gunnarsdottir I, Gisladottir E, Kiely M, Parra MD, Bandarra NM, Schaafsma G, Martinéz JA. Randomized trial of weight-loss-diets for young adults varying in fish and fish oil content. Int J Obes (Lond). 2007 Oct;31(10):1560-6. Epub 2007 May 15. https://www.nature.com/articles/0803643
 Kunesová M1, Braunerová R, Hlavatý P, Tvrzická E, Stanková B, Skrha J, Hilgertová J, Hill M, Kopecký J, Wagenknecht M, Hainer V, Matoulek M, Parízková J, Zák A, Svacina S. The influence of n-3 polyunsaturated fatty acids and very low calorie diet during a short-term weight reducing regimen on weight loss and serum fatty acid composition in severely obese women. Physiol Res. 2006;55(1):63-72. Epub 2005 Apr 26. http://www.biomed.cas.cz/physiolres/pdf/2006/55_63.pdf
 Eric E Noreen*, Michael J Sass, Megan L Crowe, Vanessa A Pabon, Josef Brandauer and Lindsay K Averill. Effects of supplemental fish oil on resting metabolic rate, body composition, and salivary cortisol in healthy adults. Journal of the International Society of Sports Nutrition 2010, 7:31 https://jissn.biomedcentral.com/articles/10.1186/1550-2783-7-31
 Clarke SD1, Gasperikova D, Nelson C, Lapillonne A, Heird WC. Fatty acid regulation of gene expression: a genomic explanation for the benefits of the mediterranean diet. Ann N Y Acad Sci. 2002 Jun;967:283-98. https://nyaspubs.onlinelibrary.wiley.com/doi/10.1111/j.1749-6632.2002.tb04284.x
 Clarke SD. Polyunsaturated fatty acid regulation of gene transcription: a mechanism to improve energy balance and insulin resistance. Br J Nutr. 2000 Mar;83 Suppl 1:S59-66. https://www.cambridge.org/core/journals/british-journal-of-nutrition/article/polyunsaturated-fatty-acid-regulation-of-gene-transcription-a-mechanism-to-improve-energy-balance-and-insulin-resistance/E7EC2373C2793F9B66DC44AF135C8AFF
 Clarke SD. Polyunsaturated fatty acid regulation of gene transcription: a molecular mechanism to improve the metabolic syndrome. J Nutr. 2001 Apr;131(4):1129-32. https://academic.oup.com/jn/article/131/4/1129/4687023
 Clarke SD. The multi-dimensional regulation of gene expression by fatty acids: polyunsaturated fats as nutrient sensors. Curr Opin Lipidol. 2004 Feb;15(1):13-8. https://www.ncbi.nlm.nih.gov/pubmed/15166803
 Clarke SD, Baillie R, Jump DB, Nakamura MT. Fatty acid regulation of gene expression. Its role in fuel partitioning and insulin resistance. Ann N Y Acad Sci. 1997 Sep 20;827:178-87. https://www.ncbi.nlm.nih.gov/pubmed/9329753
 Jump DB, Clarke SD, Thelen A, Liimatta M, Ren B, Badin MV. Dietary fat, genes, and human health. Adv Exp Med Biol. 1997;422:167-76. https://www.ncbi.nlm.nih.gov/pubmed/9361824
 Jump DB. Dietary polyunsaturated fatty acids and regulation of gene transcription. Curr Opin Lipidol. 2002 Apr;13(2):155-64. https://journals.lww.com/co-lipidology/Abstract/2002/04000/Dietary_polyunsaturated_fatty_acids_and_regulation.7.aspx
 Clarke SD, Thuillier P, Baillie RA, Sha X. Peroxisome proliferator-activated receptors: a family of lipid-activated transcription factors. Am J Clin Nutr. 1999 Oct;70(4):566-71. https://academic.oup.com/ajcn/article/70/4/566/4729181
 Davidson MH. Mechanisms for the hypotriglyceridemic effect of marine omega-3 fatty acids. Am J Cardiol. 2006 Aug 21;98(4A):27i-33i. Epub 2006 May 26. https://www.ajconline.org/article/S0002-9149(05)02187-9/fulltext
 Price PT1, Nelson CM, Clarke SD. Omega-3 polyunsaturated fatty acid regulation of gene expression. Curr Opin Lipidol. 2000 Feb;11(1):3-7. https://journals.lww.com/co-lipidology/Abstract/2000/02000/Omega_3_polyunsaturated_fatty_acid_regulation_of.2.aspx
 Gray B1, Steyn F, Davies PS, Vitetta L. Omega-3 fatty acids: a review of the effects on adiponectin and leptin and potential implications for obesity management. Eur J Clin Nutr. 2013 Dec;67(12):1234-42. doi: 10.1038/ejcn.2013.197. Epub 2013 Oct 16. https://www.nature.com/articles/ejcn2013197
 Mostowik M1, Gajos G, Zalewski J, Nessler J, Undas A. Omega-3 polyunsaturated fatty acids increase plasma adiponectin to leptin ratio in stable coronary artery disease. Cardiovasc Drugs Ther. 2013 Aug;27:289-95. doi: 10.1007/s10557-013-6457-x. https://link.springer.com/article/10.1007/s10557-013-6457-x
 Mohammadi E, Rafraf M, Farzadi L, Asghari-Jafarabadi M, Sabour S. Effects of omega-3 fatty acids supplementation on serum adiponectin levels and some metabolic risk factors in women with polycystic ovary syndrome. Asia Pac J Clin Nutr. 2012;21:511-8. https://www.ncbi.nlm.nih.gov/pubmed/23017309
 Nedvídková J, Smitka K, Kopský V, Hainer V. Adiponectin, an adipocyte-derived protein. Physiol Res. 2005;54:133-40. http://www.biomed.cas.cz/physiolres/pdf/2005/54_133.pdf
 Eric E Noreen, Michael J Sass, Megan L Crowe, Vanessa A Pabon, Josef Brandauer and Lindsay K Averill. Effects of supplemental fish oil on resting metabolic rate, body composition, and salivary cortisol in healthy adults. Journal of the International Society of Sports Nutrition 2010, 7:31. https://jissn.biomedcentral.com/articles/10.1186/1550-2783-7-31
 Delarue J, Matzinger O, Binnert C, Schneiter P, Chioléro R, Tappy L. Fish oil prevents the adrenal activation elicited by mental stress in healthy men. Diabetes Metab. 2003 Jun;29:289-95. https://www.sciencedirect.com/science/article/abs/pii/S1262363607700393
 Björntorp P, Rosmond R. Obesity and cortisol. Nutrition. 2000 Oct;16:924-36. https://www.ncbi.nlm.nih.gov/pubmed/11054598
 Salehi M, Ferenczi A, Zumoff B. Obesity and cortisol status. Horm Metab Res. 2005 Apr;37:193-7. https://www.thieme-connect.com/products/ejournals/abstract/10.1055/s-2005-861374