It things don’t work out between y’all then it’s not meant to be. Don’t stress about it he’s gonna have a problem with you for one reason or another. You’re overthinking this and that’s gonna do more harm than good. Just think of it like a hang out with someone you don’t know yet. Don’t pressure yourself to be someone you aren’t. Be genuine, and if genuine you isn’t what he wants then that’s his problem. I promise it’s gonna be alright whatever happens. Just try to breath and relax for a bit
“Hey, I think I should address something before our date tomorrow… over the past few months, I’ve gained bit of weight. I didn’t update my profile because the older pictures are where I feel most confident. I just wanted to give you a heads up so that you don’t think I was purposely catfishing you.” (Insert picture of what you CURRENTLY LOOK LIKE TODAY!)