When I started LoseIt in late February 2010, I set my plan at 1 lb/wk. After a while, I don’t remember how long, I noticed I wasn’t losing 1 lb/wk. So I added in (or maybe subtracted out) an extra caloric deficit of 200 calories. As I recall, after a while, that still didn’t do it, so I added another 150 calorie deficit (for a total of 350/day off LoseIt’s recommendation). And then my weight loss was fairly steady. (Again: recalling 1-2 years later. And of course there are many other factors in weight loss, like activity level and carb consumption.)
My point being, all other stuff aside, when your budget is 850 cal/day below the assumed maintenance level for your age, sex, and height, that gives you a lot of wiggle room to go “over budget” and still be on a negative track overall.
I admit, in some ways this is kind of like setting your clock ahead so you won’t be late, a practice I consider silly. But on the other hand, that’s not really what I’m describing. I wasn’t losing as fast as predicted, so I removed more calories from my budget, and then I was. But I’m also conscious of that fact, and it allows me to stress less when I go 5,477 over budget for the week, like last week, because that’s still 473 under my theoretical maintenance level.