Fat man skinny gf

hey im 24 and currently in a lovely relationship with a slim blonde she's beyond perfect and that not anything todo with her body , she's my soul mate , now I want to give something back and lose some weight and when I see her next I can be that man she has in her head , and although she doesn't say anything about my weight I just want to suprise her , I've tried this before by myself but it didn't work but I think with your help I may make it this time wooo lets do it