Losing weight before surgery

Hi - I am due to see the plastic surgeon at the end of the month and am a little concerned he may not allow me to go ahead with my reconstruction unless I lose weight first. I’ve really been trying hard, training for the Race for Life ( done today!!) but as I went into menopause through chemo and am now on tamoxifen I just can’t shift any weight!! Has anyone had a similar experience??I was so excited to finally get my appointment through but now feel a bit down spirited.