6 weeks of fish oil: lose a pound of fat and gain a pound of lean body mass

If you’re not afraid to take more than the manufacturer’s recommended dose, you can lose extra fat and gain extra muscle tissue with a harmless supplement like fish oil. According to a study done at Gettysburg College in the US, the effect is not sensational, but worth a try.

Fish oil is interesting in hundreds of ways for strength athletes. [It’s also interesting for endurance athletes, but that’s a different story.] Fish oil has an anti-oestrogenic effect, boosts the concentration of IGF-1, boosts the anabolic urokinase-type Plasminogen Activator and increases the effect of protein supplements. And, according to many epidemiological studies, animal studies, human experiments and trials, it also enhances the burning of body fat.

The researchers wanted to know whether healthy people lose weight if they take fish oil capsules. So they gave 22 test subjects a placebo containing safflower oil [SO] for six weeks, and another 22 subjects 4 capsules each containing 1 g fish oil [FO] every day. Each capsule contained 600 mg EPA and 200 mg DHA. The subjects took 2 capsules at breakfast, and 2 with their evening meal.

The figure below shows that nothing happened in the SO group. But the FO group gained half a kilogram of lean body mass [so also muscle] and lost about the same amount of fat mass.


According to the most widely accepted theory, omega-3 fatty acids boost the activity of the enzyme carnitine acyltransferase I. As a result, the cells pass fat on more easily to the mitochondria. If the theory holds water, test subjects would then burn more energy. But that, as the tables below show, didn’t happen.

The first table shows the results of the SO group, the second the results of the FO group.



What does happen is that the cortisol level goes down in the FO group. Cortisol breaks down muscle tissue and helps fat tissue to grow. The researchers think that it is the reduction of the cortisol level that explains the body recompositioning effect of fish oil.

Effects of supplemental fish oil on resting metabolic rate, body composition, and salivary cortisol in healthy adults.


To determine the effects of supplemental fish oil (FO) on resting metabolic rate (RMR), body composition, and cortisol production in healthy adults.

A total of 44 men and women (34 ± 13y, mean+SD) participated in the study. All testing was performed first thing in the morning following an overnight fast. Baseline measurements of RMR were measured using indirect calorimetry using a facemask, and body composition was measured using air displacement plethysmography. Saliva was collected via passive drool and analyzed for cortisol concentration using ELISA. Following baseline testing, subjects were randomly assigned in a double blind manner to one of two groups: 4 g/d of Safflower Oil (SO); or 4 g/d of FO supplying 1,600 mg/d eicosapentaenoic acid (EPA) and 800 mg/d docosahexaenoic acid (DHA). All tests were repeated following 6 wk of treatment. Pre to post differences were analyzed using a treatment X time repeated measures ANOVA, and correlations were analyzed using Pearson’s r.

Compared to the SO group, there was a significant increase in fat free mass following treatment with FO (FO = +0.5 ± 0.5 kg, SO = -0.1 ± 1.2 kg, p = 0.03), a significant reduction in fat mass (FO = -0.5 ± 1.3 kg, SO = +0.2 ± 1.2 kg, 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 ± 0.9 kg, SO = +0.2 ± 0.8 kg), RMR (FO = +17 ± 260 kcal, SO = -62 ± 184 kcal) 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 ± 0.142 ?g/dL, SO = +0.016 ± 0.272 ?g/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).

6 wk of supplementation with FO significantly increased lean mass and decreased fat mass. These changes were significantly correlated with a reduction in salivary cortisol following FO treatment.

PMID: 20932294 [PubMed] PMCID: PMC2958879

Source: http://www.ncbi.nlm.nih.gov/pubmed/20932294