I'm not much of a believer in taking diet pills in order to lose weight. There are several health risks associated with these pills and it is usually not a good solution for keeping weight off in the long run.
The best way to lose weight and meet with short-term and long-term success is to change your underlying approach to buying and cooking food. No magic supplements, no magic pills. Just focusing on eating the world's most nutritious food and getting some regular exercise at least three times a week.
This is why I would recommend the simple Flaxseed Diet. It allows you to eat as much as you want, but only foods from the list of the one hundred most nutritious foods. So while you don't have to stress about calories on this diet, with each day you are working to alter your basic approach to eating, and the types of foods you eat. Within a month on this diet, junk food will no longer appeal to your taste buds.
Check out the Three-Step Flaxseed Diet here.