Taking Fish Oil For Fat Loss?

Fish oil

Supplementing with 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% [1][2].

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 80’s and 90’s, 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. 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) [13]. 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 [14].

Omega-3 And Blood Sugar 2

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 an increase in HDL (aka the ‘good cholesterol’) as well [15].

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. [20]. 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 it’s 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 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 [2].

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 [17].

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) more over a 4 week period than those that just reduced calories [18].

A study conducted on severely obese women also found that exercise and fish oil resulted in 1.5kg (3.3lbs) more weight lost in those supplementing with fish oil than those who didn’t. The researchers also found greater levels of blood beta-hdroxybutarate in the fish oil supplemented group. Beta-hdroxybutarate 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 [19].

So How Does Fish Oil Cause the Fat Loss?

Omega 3 can literally changes our genes. For a long time it was though 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 [21]. 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 up regulating and down regulating 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 burnt for energy [3] [21] [30].

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 [34]. Generally speaking, the higher levels of adiponectin the less body fat a person has. Omega 3 also reduces cortisol levels [35] [36]. increased cortisol levels cause us to feel more stressed and can cause obesity and excess fat storage [36] [38].


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 an 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 formation which is better absorbed, more effective in the body, and generally more 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.


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Andy Mobbs

Andy is the CEO of Intelligent Labs, he's also a keen Crossfitter, a pretty good Salsa dancer and a physiology geek!