How much of what we eat ends up in the toilet?
It very much depends on what specific kind of food you are taking.
Say, if we eat more green vegetables then we are supposed to excrete more compared to a highly meat-rich diet.
Also, it depends on the food-intervals, more the interval more the absorption by body so less amount going out(but giving extreme interval is not good either).
All depends on the need of body, if body needs more than what you are giving to your body it gonna obviously excrete more.
And always keep in mind to take sufficient water, because without it all things go malfunctioning in our body.