For instance, the American Institute for Cancer Research has expressed doubt that the CLA weight Loss Supplement can actually prevent breast cancer. To lose weight, you need to take one capsule of the supplement per day 30-60 minutes before exercising. Before you take any weight loss supplement, you should do your homework. Green tea is also high in antioxidants which have been proven to drastically slow the aging process when taken over a long period of time. Hence, anyone can claim to be the best weight loss supplement even without valid proof.