[citeguised]

I guess lots of people do the mistake of having a too-small daily deficit while counting.

It's obviously not an exact science.

If you go with a daily reduction of 1000 kcal, then it doesn't matter if you have an error-margin of 300-500 kcal, you still lose weight.

If you only try to save 500 a day, and maybe are not too exact in your logging, you might not see an effect at all.