Because of cholesterol issues (my overall number is low, but my "good" cholesterols are TOO low!) my PCP is having me take fish oil capsules. (I've got my husband on them, as well - my doc recommended the Kirkland (Costco) brand as they are a good value and you get the highest dose of the Omega oils.
Dr. Andrew Weil had a nice Q&A on Omegas that you can access here
. (not saying I agree with ALL of Dr. Weil's writings across the board but this is pretty common sense info IMO).
Also - here's a good article on WebMD to check out
Lastly, SupplementWatch's info on Omega-3's
My personal opinion? I don't think that they help with weight loss per se - I think that most people trying to increase their Omega-3 intake are going to eat healthier ANYWAY (perhaps following a Mediterrean-style WOE) so they might see a weight loss, but if anyone is selling Omega-3's as a weight loss miracle pill on their own...I don't think so. But I wouldn't dissuade anyone from trying to get in more O3's - just don't get suckered into buying unnecessarily pricey ones because they advertise it as a weight loss aid!