In a very recent study, which is going to be published in the Journal of the International Society of Sports Nutrition Noreen et.al. investigated the effect of 4g/d of fish oil supplying 1,600mg/d eicosapentaenoic acid (EPA) and 800mg/d docosahexaenoic acid (DHA) over 6 weeks on resting metabolic rate (RMR), body composition and salivary cortisol in 44 healthy men and women (34+13y, mean+SD. The results were quite astonishing:
Compared to the safflower oil group (SO), there was a significant increase in fat free mass following treatment with fish oil (FO) (FO= +0.5 +/- 0.5kg, SO= -0.1 +/- 1.2kg, p=0.03), a significant reduction in fat mass (FO= -0.5 +/- 1.3kg, SO= +0.2 +/- 1.2kg, p=0.04). and a tendency for a decrease in body fat percentage (FO= -0.4 +/- 1.3% body fat, SO= +0. 3 +/- 1.5% body fat, p=0.08). No significant differences were observed for body mass (FO= 0.0 +/- 0.9kg, SO= +0.2 +/- 0.8kg), RMR (FO= +17 +/- 260kcal, SO= -62 +/- 184kcal) or respiratory exchange ratio (FO= -0.02 +/- 0.09, SO= +0.02 +/- 0.05). There was a tendency for salivary cortisol to decrease in the FO group (FO= -0.064 +/- 0.142ug/dL, SO= +0.016 +/- 0.272ug/dL, p=0.11). There was a significant correlation in the FO group between change in cortisol and change in fat free mass (r = -0.504, p=0.02) and fat mass (r = 0.661, p=0.001)This study is of particular interest, because the participants were healthy individuals not old men or patients with diabetes, heart disease or whatever. What's more the intervention period (6 weeks) is reasonably long and the supplement dosage is realistic and affordable. So, if you do not already have a bottle of fish oil caps or some plain cod liver oil (it does not taste so bad anymore, don't worry), you better get up and get one, for weight loss and muscle gain are not the only positive effects science ascribes to a nutrient that ain't part of our regular western diets.