The "Shrek Effect"is an unnatural occurance that happens to young women after high school and college. The young woman is naturally beautiful/ and or cute to begin with, but through out the years after her education, the shrek effect sets in. May it be the cause of a horrible heart shattering break up or that she spent too many nights curled up with a snuggie, eating sherbert ice creaming watching soap operas as she cries silently on her Scott Baio pillow thinking that the right guy will just "find her". These women put on a good chunk of fat and sometimes get beaten with the ugly bat numerous times. These events will lead to the woman developing the "Shrek Effect". A young beautiful woman turning into a fat, ugly, or just unpleasant to glance at. This effect would be considered the opposite of the "ugly duckling syndrome"
Remember Jessica from high school? yeah she got fat, looks like the shrek effect happened. pity.