I could pick any recent popular diet book and it would tell me pretty much the same thing. But calories are a gross estimate. You can't predict or really know how much you expend on a day to day basis. A few extra stand ups from the chair you're sitting on, and we could be talking 30-40 cal slip-offs. Then when I see a daily "norm" of 1683 cals set up by some poor dude and putting it out on his blog, I can't help but laugh at it. Before finally starting to eat less, I had long thought eating to gain in weight to add muscle was the way to go, that I was doing the right thing as a bodybuilder. It turns out I was wrong, or better yet, it wasn't the best way to do it. Now I have proved to myself that I can lose weight by simply eating less, with only roughly counting the amount of needed protein (70-120g per day), and making sure to get carbs somewhere above 100g daily to be at a safe distance from going keto. That's it. When I finally do get lean (and the previous 3 months have shown that it's only a matter of time), I don't think I will change my eating habits in an incompatible way. I'll simply start eating a bit more.