You can also cut 250 calories/day from your
diet and use up 250
calories/day in exercise. This is, by far, the best, and easiest, option.
I'm not familiar with "slim in 6" program, but if you enjoy it and it keeps you moving, go for it. You can work into it slowly and gradually increase the time spent.
Be sure to implement a healthy diet that contains a lot of protein, in the form of meats, chicken, fish, eggs dairy, beans, etc, along with plenty of veggies.