Why do I over eat when I consume mononunsaturated fats?

I love avocados, olives, nuts – especially almonds and dark chocolate.

When I eat these items its akin to eating chips or something similar, I want more. Even though I am full. Like the mechanism indicating fullness gets overridden.

Am I only the one who has the problem? Is there a reason for this?

How many monounsaturated fats should eat a day. Can one become fat from overindulging in these?