Srimate Raamanujaye Namha,

There are many levels of fasting.. depending on ones situation of health and work one can choose an apt one.

Next level beyond nrijal is water alone.

Next to that is to take water and fruits and milk

Next to that is to take water , fruits and milk and non grain ( no rice, dal, beans etc)..there are some seeds like Saamai, quinoa, amarnath flour etc which are not grains, those can be taken, but cooked ideally without oil and mustard seeds and sambhar powder ( to be replaced by ghee, jeera and plain chill powder)

Beyond this level is to take broken grains like upma, idly, dosa and chappathy. (this is allowed in Sri Sampradayam , but not in gaudiya sampradya).

Hoep this helps

but the main reason to fast is to minimize bodily needs keep stomach light and spend more time in sharavana, keerthanam etc on that day

These kind of questions are in this forum, you can type ekadasi in search option you may see few thread,

adiyen

Raamanujadasan