Fish oil supplementation found to benefit body composition

A couple of weeks ago one of my blog posts focused on a study which suggests that getting adequate sleep can have beneficial effects on body composition. While the mechanism that may be responsible here is not known, I speculated that it might have something to do with cortisol – lack of sleep can cause levels of this stress hormone to rise, which in turn could lead to a tendency to increased muscle breakdown and enhanced fat deposition in the body.

The idea that cortisol might have something to do with body composition has come up again in another recent study. In this particular study, individuals were randomised to take either 4 grams of safflower oil or 4 gram of fish oil (containing a total of 2400 mg of EPA and DHA) for a period of 6 weeks. At the end of the study, those taking the fish oil were found to have higher fat free mass (fat free mass in the body includes muscle) as well as lower fat mass. In addition, those taking the fish oil were found to have a tendency to lower levels of cortisol, although this was not statistically significant. The authors of this study do suggest that some ability to reduce cortisol levels might explain, at least in part, the ability of fish oil to improve body composition.

However, the authors of this study also consider other potential mechanisms. For example, they cite evidence which shows that omega-3 fats such as EPA and DHA have the ability to enhance fat ‘oxidation’ (metabolism) in the body, partly by facilitating the transfer of fat into the ‘mitochondria’ (the structures in the body’s cells responsible for turning fuel into energy). Omega-3 fats appear to stimulate fat burning too. Other work suggests that omega-3 fats can increase something called ‘thermogenesis’ (the production of heat in the body), as well as increase lean body mass (which would also tend give the metabolism a boost).

The authors of this study make mention of research which found that fish oil supplementation significantly reduced fat mass compared to supplementation with sunflower oil [2].

Fish oil has been linked with a variety of benefits for health, particularly with regard to cardiovascular disease prevention and enhanced brain function. Mounting evidence also links this particular type of fat with improvements in body composition, including lower levels of fat in the body.


1. Noreen EE, et al. 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

2. Hill AM, et al. Combining fish-oil supplements with regular aerobic exercise improves body composition and cardiovascular disease risk factors. Am J Clin Nutr 2007;85:1267-1274

11 Responses to Fish oil supplementation found to benefit body composition

  1. Margaret Wilde 21 October 2010 at 12:47 pm #

    Dr Briffa

    As I am extremely sensitive to salt and try to avoid added salt where possible, I do not have the same freedom to eat oily fish that other people may have. So for quite a long time – maybe a year, I’m not sure – I have been taking a daily capsule of 1000mg of Omega 3 fish oil, containing 300mg of active EPA/DHA. Do you think this is an appropriate amount to take or would you suggest I take more?

  2. Chris 22 October 2010 at 11:13 am #

    I wonder have you considered that the human diet has co-evolved with human physiology over several millions of years? Or that riverine and coastal habitats must surely have been important to prgenitors in the early phases of migration from the Rift Valley?

    Despite common consensus that excess salt is ‘bad’I have difficulty reconciling the simple maxim that salt is bad with the observation that fish and seafood are naturally high in salt.

    Marine fish and seafood may have been important components of the diets of early humans who bagan migrating from the Rift Valley. Excavation work at Pinnacle Point and the existence of huge middens suggests shelfish were an important component of the diet of ancient humans that once inhabited the area. It has even, jokingly perhaps, been postulated that shelfish, being high in zinc, could have contributed to human proliferation.
    Work at Pinnacle Point, headed by Prof. Marean, aspires to date the earliest known hearth from archeological remains to roll back, if you like, the earliest known certainty of the human use of fire for cooking.

    Even today marine food is important to the indigenous diets of native Alaskans or Inuit. One can’t help thinking these diets are relatively high in salt. Moreover these poeples are observed to exhibit health stress when thay adopt features of western dietary influences. However I concede that other indigenous diets may be low in salt.

    Is salt bad per se or is too much salt bad if in the presence (or absence for that matter) of one or more other dietary factors? I don’t know with surety. Does anyone?

    Useful titles:
    The Quest for Food; It’s Role in Human Evolution & Migration; Ivan Crowe, 2000. Available from
    Catching Fire: How Cooking Made Us Human, Richard Wrangham, 2009.

  3. Margaret Wilde 22 October 2010 at 3:19 pm #


    I certainly have considered that the human diet has co-evolved with human physiology over several millions of years. Unfortunately the human diet that co-evolved with human physiology did not not include the powerful pharmaceutical drugs that many doctors too readily, and all too often inappropriately, prescribe, frequently in high dose, and with inadequate knowledge of side-effects, to their unfortunate patients/victims.

    If you read my Mensa article here – – you will realise that this is not a matter of academic opinion, it is a matter of personal experience. I’d be dead if I hadn’t made my discoveries about salt.

    Prescription drugs caused my salt sensitivity. Fortunately, though very late in the day, I was able to work out what had happened and why, and my website helps other people to prevent or reduce their own suffering from salt sensitivity and from certain powerful prescription drugs.

  4. blackdog 22 October 2010 at 4:27 pm #

    Margaret, I would always advocate that salt is used with caution and I know you have had good results from it’s restriction. It is far from the only factor and you should be aware of confounding elements in diet that may have had benefits, especially if you undertook more than one change at the same time.
    Some interesting resarch on salt from Berkeley can be viewed here;
    I note your use of Omega 3 oil capsules which I applaud, with a slight codicile; always ensure the ratio of EPA to DHA is at least 2:1 or better and do not exceed 1.5g overall. EPA and DHA compete for the same metabolic pathway, so keeping the EPA higher is best to obtain the maximum benefit. Overuse can encourage the oxidation of DHA contributing to AGE’s. Also remember to restrict intake of Omega 6 as this is abundant in the diet and also competes with Omega 3. Bit of a tightrope I’m afraid.

  5. Steve F. Foster 22 October 2010 at 5:03 pm #

    Why is there no reference to omega-3/omega-6 ratios? According to my understanding the sought for effects are through relative not absolute dosages. Similarly, Margaret & Chris’s comment seem to be about sodium salt (NaCl), whereas ratios with Potassium salt (KCl) seem to be a crucial issue. The human body requires fats and salts to survive and the issue here is relative amounts required to flourish! I’d like to see more definitive discussion of these points. Thank you.

  6. Erin 22 October 2010 at 5:22 pm #

    Margaret simply said she is sensitive to salt

  7. Margaret Wilde 22 October 2010 at 6:46 pm #

    Thank you, Erin. I appreciate your support. I definitely am extremely sensitive to salt. Salt sensitivity is not something else. It is salt sensitivity.

    It seems that any mention of salt sends people leaping onto their hobby horses, and few of them appreciate the significance of salt sensitivity.

    Yes, I am aware of the need to restrict intake of Omega 6, partly from the extremely helpful advice given in the pages of this excellent blog of Dr Briffa’s.

    If I have not expressly said it before, let me say now: Thank you very much, Dr Briffa, for this blog and the thoughtful advice you so kindly provide for your readers. I recommend your blog to everyone I can.

  8. Diana1 22 October 2010 at 11:53 pm #

    There is salt and salt. When scientific research is done focussing on salt eg its effect on blood pressure I do wonder what type of salt is used, or if there is even an awareness that the type used could make a difference to the results. Salt that is derived naturally from the evaporation of sea water will contain a mix of other elements (eg it is rich in magnesium) and that would be the salt our ancestors used. Table salt that is freely available in the supermarkets – what most people use – will probably be just NaCl with an anti-caking agent added.

  9. John Briffa 23 October 2010 at 4:05 pm #


    Thanks for your kind words – they are genuinely appreciated.

    You are most welcome!


  10. chris aspey 25 October 2010 at 7:56 pm #

    At the camexpo yesterday Dr Tom Gilhooly gave a very interesting presentation on Omega 3. However, I am left a bit concerned as a member of the audience raised a question on some other research, but he was abruptly hushed. Would anyone know why this would happen and if there are any indications for not supplementing with omega 3?


  11. Barry 26 October 2010 at 1:07 pm #

    Dr Briffa

    It it possible to have too much of a good thing ?? There is increasing evidence that PUFA’s may not be the all singing all dancing essential nutrients. I’ve always been an advocate for their anti-inflammatory, cardio, cognitive and body comp effects. But this review asks questions, I would be interested to hear your opinion, thanks

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