Is it common to have large and frequent poops after eating food that contains a lot of fat?

This could be normal but you could also have a problem absorbing fats. Anytime you eat there is the gastrocolic reflex, which will make you have a bowel movement. If you are having large, foul smelling stools that float in the toilet, then your stools contain a lot of fat due to a problem absorbing the fat. This can occur with chronic pancreatitis, Cystic Fibrosis and some other conditions. If you are losing weight, then this is particularly concerning and you should be evaluated by a doctor. Bowel movement size and frequency does vary from person to person.

As I have elderly I have discovered to love cabbage in all varieties. Stir-fried, with rice and greens. Great supply of fiber additionally. It is remarkable with fried rice and Dungeoness Crab. Sandwiches too.