5 days won’t give you much in terms of results.
You shouldn’t have to count exact calories, but it’s good to have an idea how many your body theoretically needs per day and then try not to go too far over that too often.
Don’t just eat junk and expect IF to solve any weight problems. A balanced diet will make IF far more effective.
Calorie counting is generally frowned upon while doing IF, but I try to make sure I stay within 1500-1700 calories per day, and make sure I’m eating well. It’s all about balance. Find what works for you and stick with it