Yes, it is that simple.
For the five days that you are not fasting you should eat at least your BMR, preferably even more. Most will try and stick to their TDEE, some do not bother to count calories on fast days at all and only try to make healthy choices most of the time.

There is no need for diet pills, supplements or special diet foods, only scales, calorie charts and some basic cookery skills. It might take a while to find the right meal structure for you as everyone is different. Some fasters eat only one meal on a fast day, some several small meals, some not at all. Most fasters will prefer a protein/vegetable combination for the fast day food like white fish and steamed vegetables as this seems to make you fuller for longer but then again, some are happy eating carbohydrates. Sometimes it takes a little while to get the fast days down to 500/600 kcals but that should not discourage you.

It is useful to watch the BBC Horizon program “Eat, Fast and Live Longer” and to read the book by Michael and Mimi. The book has a lot of information and also some low calorie recipes to get you started.

The main thing is to find what suits you best and then stick to it.