If you can cut out, say, added sugar from your diet, you'll hit that target easily without the need for knowing the calorie content of everything you eat. I know people who have eating disorders who obsess over every calorie and it isn't healthy. That said, keeping a food diary can be helpful at first because people often consume lots of extras without realising it. You don't need to calorie count to know that three extra biscuits haven't done you any good.
It's now thought to be better to focus on portion size, eating mindfully (so only eating what you really enjoy, when you are hungry and stopping when full) and adding lots of foods known to be good for us - an abundance of fruit and veg, nuts and seeds, olive oil etc.
