Although it is very possible to lose weight without cardio workout by using pills, but healthwise it is not advisable. I agree it might be easier to burn fats through the use of pill method but it also has it own side effects.
These pills basically works with the metabolic system by speeding up the rates food substances are converted to energy. They reduce one's appetite thereby making one full for a long time and eat less of calories.
Some of these pills are; hydroxycut, meratrim CLA(conjugated linoleic acid), ketoboost foskolin, caffeine, etc.
Ideally, cardio exercise it still the best way to lose weight. With it you won't have to worry about the side effects the pill method poses such as anxiety, insomnia, jitteriness, irritability etc.