Does Fish Oil Improve Body Composition?

Omega-3 Fatty Acids, Body Fat, and Muscle

Does fish oil help with fat loss and muscle gains or not? How much do you have to take? We finally have the answer. Check it out.

Follow the science, they say. Sometimes they even scream it. Well, if you’ve followed the science of fish oil supplementation, here’s where you’ve traveled the last twenty years:

  • Fish oil improves body composition. More muscle and less fat! Yay! – Science
  • No wait. Fish oil does NOT improve body composition! Boo! – Also Science
  • Hold on! Fish oil DOES improve body composition! Maybe? – Still Science

We followed the science, but the science was drunk and drifted from one side of the road to the other. Does fish oil (omega-3 fatty acids) shift our body comp in a favorable direction or not?

Let’s jump to the answer:

Yes, it does, if you get enough of it in you and give it enough time to work.

See, all those conflicting studies followed different parameters. Some used mega-doses of fish oil; some used puny doses. Some were very short in duration; others were longer. Some studied overweight people; others looked at gym goers and athletes.

With all such studies, smart folks read past the histrionic headlines and dive deeper. But the latest fish oil study should clear everything up, once and for all.

The New Study

This study is cool because it used high-dose fish and resistance-trained men and women. The participants were divided into two groups:

  • A group taking 4.5 grams per day of fish oil.
  • A placebo group taking 4.5 grams per day of safflower oil.

Both groups used the same 3-day-a-week lifting program for 10 weeks. They followed their usual diets but were asked to eat at least 1 gram of protein per kilogram of body weight per day of protein, which is pretty minimal.

The researchers measured body composition with DEXA and measured everyone’s omega-3 index score. That test let researchers know if they used enough fish oil to get inside the membranes of red blood cells and skeletal muscle cells. In this case, they did.

What Happened? Tell Me, Tell Me!

  • Lean Body Mass: The fish oil takers gained an average of 4 pounds. The placebo group gained 3 pounds.
  • Fat Mass: The fish oil group lost 2 pounds. The placebo group lost nothing.
  • Body Fat Percentage: The fish oil group lost 1.4%. The placebo group lost 0.6%.
  • Maximal Strength – Squat: The fish oil group added an average of 53 pounds. The placebo group added 42 pounds.
  • Maximal Strength – Bench Press: The fish oil group added 24 pounds. The placebo group added 14 pounds.

The fish oil and placebo groups did the same workouts and ate roughly the same foods as they did before the study, but the fish oil group:

  • Gained 1 extra pound of muscle while losing 2 pounds of fat compared to those who didn’t take fish oil.
  • Increased their max squat and bench press by 11 and 10 pounds, respectively, compared to those who didn’t take fish oil.

Well, I’m impressed. Like you, I mainly take fish oil for health, longevity, and cognitive benefits, but if it helps me gain a little more muscle, lose some fat, and bolster strength gains, then I’m definitely not going to skip my daily dose.

And this is where the science gets “drunk.” The researchers here said that most of these improvements were (wait for it) statistically insignificant. Yeah, Mr. Ph.D, without saying you don’t work out, tell me you don’t work out.

In defense of the pencilnecks, this is what they usually say. But they’re also looking at these results through the lens of a 10-week study. You’ll probably keep lifting for longer than 10 weeks, so you’ll keep reaping fish oil’s body composition and strength benefits. Also, an experienced lifter is very happy to lose an extra 2 pounds of fat and build a bonus pound of muscle in just 10 weeks.

Luckily, the scientists also looked at “effect size.” That’s the magnitude of the difference between the two groups. After considering this, they said, “Yeah, okay, fine. That’s actually a whopping difference.” (I may be paraphrasing a little.)

But What If You Take EVEN MORE Fish Oil?

The participants in this study took 4.5 grams of fish oil daily, which required them to swallow 7 capsules of whatever brand they were given. That’s more omega-3s than you find in Target and Wal-Mart brands. But our fish oil supplement, Flameout, has 5.5 grams, and you only need 4 capsules.

Could that extra gram improve these already impressive results? Maybe the next study will test that out. Until then, rest assured that the consistent intake of high-dose, concentrated fish oil (preferably high in DHA) does give you the edge when it comes to body composition. Add that to its long list of benefits.

Note: Shoutout to T Nation contributor Bill Campbell, Ph.D. for pointing out this study in his excellent Body by Science newsletter.

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  1. Heileson, et al. The effect of fish oil supplementation on resistance traininginduced adaptations, Journal Of The International Society Of Sports Nutrition, 2023, VOL. 20, NO. 1, 2174704.

I’ve seen great results with my physique athletes using 5-8g daily during a fat loss phase. More-so when it’s Flameout (possibly due to the higher quality versus generic fish oils, and added CLA). We still track those 5-8g as part of our daily allocated fat intake. We also increase the dose gradually.


Awesome. Thanks for the real-world feedback, Gareth!

Does it matter when you take the Fish Oil to get the best “bang for your buck”? I normally take mine with my evening meal. Is there a better time to take it?

I think it may have been coach Thibs that recommended taking one gram a fish oil per body fat percentage value for improved body composition. Now, that seemed like a lot of fish oil. However, I did try it during my last fat loss phase last summer and found it to work very well. Especially when using Flameout!


Great article.
Important to note the QUALITY of fish oil really counts. But how do we know what’s quality? What if the oil is rancid? What if the oil is mercury tainted?

Let’s not forget oleuropein, which you’ll get in high polyphenol olive oils, and olive leaf extracts. 3 table spoons a day for longevity and staving off cancers. (watch out for the fake commercial oils)
Oh, and also raw virgin coconut oil.
The later on empty belly first thing in the morning to turn on the fat burners.

Evening meal is a great time.

There’s no real “bad” time to take fish oil and some people like to divide theirs up over several meals. I would, however, avoid taking it immediately pre and post-workout so the fats won’t interfere with any workout nutrition supplement like Surge Workout Fuel. (It probably wouldn’t interfere too much, but just in case.)

I personally take all 4 Flameout softgels at night before bed to squash any excess cortisol. Here’s some INFO about that.


Quality definitely counts. Also helps if it’s highly concentrated so you don’t have to take 7 to 15 capsules per day to get an effective dose.

I can tell you that Flameout is purified by molecular distillation and stringently tested for PCBs, dioxins, mercury, and other heavy-metal contaminates. It’s also self-emulsifying, making it better absorbed with less aftertaste (if any). It uses pharmaceutical-grade DHA/EPA re-esterified triglycerides.

I was a fairly early adopter of fish oil (early 90s) and man, back then you’d need 15 to 20 capsules just to get what’s in a one or two Flameout softgels. They didn’t even call it “fish oil” back then because who would want to swallow that?! They called it “marine lipids.” You’d open the bottle and the whole house would stink for an hour. I swear they just squeezed a sardine back in the day. Fish oil has come a long way since then and Flameout leads the pack.

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I suppose I was a similar case. It was John Parrillo that introduced me to essential fatty acids. I did so with liquid flax seed oil. Before the 1990’s ended, a friend convinced me that the fish version provided better absorption. I switched my essential fatty acid source to fish oil. I took my fish oil by the tablespoon from a bottle of liquid fish oil. It was less than tasty in the '90’s, but flavorings like lemon makes it not at all bad.

Currently I am taking a tablespoon of fish oil in the AM and two capsules of Flameout at bedtime with D3 and ZMA.


Me too. We know now that most of that health-food store flax oil was sold rancid. No wonder it was so gross!

Also, flax seed oil has to be converted into EPA/DHA in the body, whereas fish oil already is EPA/DHA. The fish kindly converted it for us.

Evening meal is probably best if it’s your fattiest meal of the day. Apparently it’s digested better when taken with other fats.

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All the flax seed oil that I bought was refrigerated. Might it too have been rancid?

Before I started buying Carlson’s fish oil, I always bought fish oil that was refrigerated (usually Barlean’s).

Maybe. Refrigeration and dark bottles helps though. The old guidelines were: if it smells burnt, bitter, or chemical-like, it’s rancid. Should taste mild and nutty.