Is herbal products use full to reduce health....?

recently a health club by name health care--wealth care is being put in an apt when consulted she said there are products useful for bot to reduce weight and gain weight..and they are some powders to be mixwd in water and have to take in the morning..and she said to pay 945 for 1 week..and can i go with it as i am 10 kgs over weight than i am..and even i do brisk walk daily can i opt this..suggest me.