Get simmer and more muscular with fish oil

Taking a fish oil supplement boosts calorie expenditure and fat burning while doing low-intensity exercise, and it stimulates the growth of muscle tissue, Canadian nutritionists at the University of Guelph conclude in PLoS One.

The researchers divided 24 healthy women, aged between 60 and 74, into two groups. One group took 5 g fish oil every day for twelve weeks. Two grams of the supplement consisted of the polyunsaturated omega-3 fatty acids DHA and EPA. The other group took a placebo.

The researchers examined the women several times in the laboratory during and at the end of the supplementation period. They took lots of measurements including the women’s body composition and their calorie expenditure.

Fish oil supplementation increased the women’s calorie expenditure when at rest and during low-intensity exercise [the women had to cycle for 30 minutes at a gentle pace].

T1: after 0 weeks; T2: after 6 weeks; T3: after 12 weeks.



When at rest the women who had been given fish oil burned the same amount of fat as the women in the placebo group. But during low-intensity exercise the women in the fish-oil group burned noticeably more calories than the women in the placebo group.

The women who took fish oil lost just under 1.5 kg body fat during the experiment, but the effect was not statistically significant. The supplementation also increased the women’s lean body mass by over 1.5 kg – and that effect was statistically significant.


Before and after the supplementation period the women did the Timed Up And Go test – getting up and sitting down again as fast as possible for a certain amount of time. The amount of time it took them to do this decreased, indicating that the women in the fish-oil group had gained strength.

“The consumption of 5 g/d of total fish oil is difficult to maintain for many older adults, due to increased digestive issues (gastrointestinal discomfort) and the size of the capsules”, the researchers admitted. “Determining the optimal dose of fish oil required to illicit [sic] the metabolic and physical benefits is needed.”

Omega-3 Fatty Acid Supplementation for 12 Weeks Increases Resting and Exercise Metabolic Rate in Healthy Community-Dwelling Older Females


Critical among the changes that occur with aging are decreases in muscle mass and metabolic rate and an increase in fat mass. These changes may predispose older adults to chronic disease and functional impairment; ultimately resulting in a decrease in the quality of life. Research has suggested that long chain omega-3 fatty acids, found predominantly in fatty fish, may assist in reducing these changes. The objective of this study was to evaluate the effect of fish oil (FO) supplementation in a cohort of healthy, community-dwelling older females on 1) metabolic rate and substrate oxidation at rest and during exercise; 2) resting blood pressure and resting and exercise heart rates; 3) body composition; 4) strength and physical function, and; 5) blood measures of insulin, glucose, c-reactive protein, and triglycerides. Twenty-four females (66 ± 1 yr) were recruited and randomly assigned to receive either 3g/d of EPA and DHA or a placebo (PL, olive oil) for 12 wk. Exercise measurements were taken before and after 12 wk of supplementation and resting metabolic measures were made before and at 6 and 12 wk of supplementation. The results demonstrated that FO supplementation significantly increased resting metabolic rate by 14%, energy expenditure during exercise by 10%, and the rate of fat oxidation during rest by 19% and during exercise by 27%. In addition, FO consumption lowered triglyceride levels by 29% and increased lean mass by 4% and functional capacity by 7%, while no changes occurred in the PL group. In conclusion, FO may be a strategy to improve age-related physical and metabolic changes in healthy older females.