[zeroCalories]

I agree that it's a range, and that's precisely why it's hard to get right. If I go for a day trip on the weekend with my wife I might burn 1000 extra calories walking. If I have a mystery coffee at my friend's house I have no idea how much I just consumed. The margins are too close that it becomes difficult to make consistent progress.

[edaus]

Sure it can be difficult, especially if you compare day to day, but if you compare or weekly bi-weekly averages ( both weight and calories ) it becomes way more doable. Are you just supposed not to try since you can't exactly find the numbers each day?

With the approach above you don't really care about acute changes in intake or activity and look at the bigger picture and change the things that are constant and under your control.

It's not simple but it also doesn't mean you should just give up.

[zeroCalories]

Yeah, but why do something difficult when you could do something easy? Going on a 300 cal deficit a day, you have 2100 calories a week. A couple bad days could easily throw off all your progress, and you might not even know what messed you up. If I eat at a 3000 cal deficit I'm gonna lose weight even if I don't do things perfectly. Go out for ice cream? Skip the gym? Who cares?