Taking a high dose of fish oil daily for three months may calm down certain immune cells in overweight women, and this calming effect can last for at least a month after they stop taking it.

We analyzed the available evidence on high-dose omega-3 supplementation in obese women and found that 43 studies or assertions support the idea that it may reduce pro-inflammatory gene expression. No studies in our review contradicted this. The evidence we’ve reviewed suggests that taking a high dose of fish oil daily for three months may help calm certain immune cells involved in inflammation in overweight women. This calming effect appears to last for at least a month after supplementation stops, meaning the change isn’t just temporary while taking the pills [1]. We don’t know exactly which genes are affected or how strong the effect is across different body types or dosages, because the evidence we’ve seen doesn’t break it down that way. We also can’t say whether this change in immune cell activity leads to better health outcomes like less pain, improved insulin response, or weight loss — those connections weren’t part of what was reviewed. The number of supporting assertions is high, but we only have one clear assertion to work with, and we don’t know how many unique studies that represents. It’s possible the 43 points come from overlapping analyses of the same few trials. What we’ve found so far leans toward the idea that high-dose omega-3s can influence inflammation-related activity in obese women, and that the effect may stick around after stopping. But we don’t yet have enough detail to say how consistent this is, who benefits most, or what the ideal dose or duration might be. If you’re an obese woman considering omega-3 supplements to help with inflammation, this evidence suggests it might help — and the effect could last a bit after you stop. But more research is needed to understand how, for whom, and why.