If her diet is good then results will be good, clens a great fat burner, I hate the stuff it gives me terrible headaches i refuse to ever take it again but if one can tolerate it then it does work very well. But if your fiance not going be on a good diet in a caloric deficit then it wont do a damn thing for her. She wiill ultimately just be stressing her heart for no reason. Personally id say get rid of the shit (the clen), its got some shitty acute side effects and many medical studies showing its dangers to the heart. I would rather do an extra 30mins of cardio fasted every morning then take that stuff. The results will be similar, clen increases ones BMR by about 10%, you can easily burn 10% of your daily calories in one cardio session, for a girl thats like 150-200 cals max. Thats just my 2 cents. Some love the stuff but the headaches kill me and im already stressing my heart running gear and carrying all this weight around.