There was something on the Ten news the other day about taking Fish Oil Capsules. Taking them helps speed up your metabolism or something. Apparently in a trial, people were eating what they wanted, having 6 capsules a day, and taking three 45 minute walks a week. People lost anywhere from 2 to 5kg in 12 weeks (which isnt a whole heap, but surely weight loss would increase if you were eating a controlled diet and exercising more)...
Thats my two cents worth