The amount of fat you can eat on a low-carb diet is not generally
limited, except that you should not stuff yourself with anything,
including fat.
More important than the amount of fat, which should make up between
65 to 75% of your dietary calories, is the type of fat.
Partially hydrogenated trans fats should be strictly limited.
Most margarines and shortenings contain a lot of these harmful
fats.