How is it they say you need to eat more to lose weight?

So I am still having a hard time grasping the eating more to lose weight concept. My RMR is 1452 and the site I use to log my foods and exercise give me a deficit of 969 Calories and I have gained weight. Now I would think that as long as I am eating 1500 calories a day that I would be losing the weight, but I keep getting told that I am not eating enough, as I am given about 2300 calories to eat when I work out. I'm at 175.5 so I am still doing ok but 2 weeks ago I was at 173 and maybe I put on a lot of wright on my off week when I was sick and eating so much and have lost some of that weight. I have been at this thing for 4 years now, one would think that I would get it by now but I still don't. Sure I lost a ton of weight and learned how to eat good and somewhat balance my lifestyle using Nutrimiror but my #'s on the site have always been all over the place and never accurate. Ah well just thought I would throw this out there, not really much going on in my little world right now. Walked today since the Gym was closed so I burned some calories and did my thing to keep active!