Gaining weight on nexplanon??

I have the nexplanon implant in my arm and was told by my doctor that there was very small chances of gaining weight based on the implants she had done. My friend says I'm gonna gain like hell, and that scares me because I'm a recovering anorexic/bullimic scared of relapsing. If anyone else on here can let me know how much if any weight you've gained on nexplanon it would be appreciated