Hi There, I'm Wanting To Start A Weightless Program Called

Hi there, I'm wanting to start a weightless program called herbal life! Where you take skinny tea, meal replacement shakes and weighloss tablets and such things! I'm only doing this diet for 4 weeks! I'm not overweight but I'm just using it to get back on track and kick start my healthy living again! If I stock taking these things after 4 weeks will I gain weight back ? Or will it stuff up my already current metabolism ?