You will gain it all right back and then some unless you have changed your total behavior (ie: excercise) and eating and dietary habits.
Over the past 20+ years I tried it all. I used pills, dropped it off, it came back, I used diets, weight watchers, nutri-systems, slim fast, you name it. I read an article last summer that over 85 percent of dieters regain the weight after they stop. That is when I decided to change my whole lifestyle, diet and behavior.
I do not want to be in the 85%. I drink a strong cup of coffee or Pur-ehr tea occasionally to curb my appetite, but by changing my whole diet, cutting carbs, staying away from cakes, icecream, cookies, potato chips and fast food burger places, eating plenty of lean protein and veggies.
I have nothing against using a pill or diet program to get you started, but once you get going you need to drop the pills and change what you eat.
There is NO diet I know of where you can have all the greasy burgers, fries and cake you want.