This is a lit review. The studies cited were: - Participants assigned to fish oil + exercise, fish oil, corn oil, and control. After 12 weeks, only fish oil +

This is a lit review. The studies cited were: - Participants assigned to fish oil + exercise, fish oil, corn oil, and control. After 12 weeks, only fish oil + exercise resulted in significant fat loss, but no exercise only control group. - Participants assigned to fish oil + exercise, fish oil only, exercise only, and control. After 10 weeks, no body composition differences noted between any groups, but no group was very fat to begin with. - Fat participants assigned to either fish oil + exercise, sunflower oil + exercise, fish oil alone, or sunflower oil alone. Fish oil + exercise significantly outperformed other protocols after 12 weeks. - Fat participants assigned to either fish oil + exercise or placebo + exercise. After 24 weeks, both groups lost about 5% of their fat without any significant difference between groups. - I have no idea what "RBC deformability" is, but two studies assessed it by having participants perform cycling time trials in a hypobaric chamber. One study gave fish oil for 6 weeks and found a significant difference. One gave fish oil for 3 weeks and found no difference. - Well-trained cyclists assigned to either take fish oil or olive oil for 8 weeks. Fish oil group saw significantly lower heart rates during submaximal exercise, but no difference in peak oxygen consumption. - A 60-day study of national football players assigned to either fish oil or control. The fish oil group saw better lipid profiles at the end. - A study of elite Australian rules football players assigned to either fish oil or sunflower oil while training normally for 5 weeks. They performed treadmill speed trials at the end. The fish oil group had lower heart rates while running, but no performance difference between groups. Take of this what you will. The reasons usually given to take fish oil are for long-run heart health. This seems to indicate you probably won't perform better or lose more fat compared to someone who exercises the same way but doesn't take fish oil, but you may see improvements in blood lipid profile, lower heart rates, and less oxygen consumption during submaximal exertion. All of those sound like good things to me.