Well there isn't really enough information about if the Loch Ness Monster really truly exists are not, but we can only go by what we know like ST. Columbia he apparently stopped the beast from attacking an expecting swimmer when he spoke the words "Go back from the depths of whence you came" he said raising the cross of God.
The "creature" turned away from the man and swam back into the cloudy, murky waters. Not many sightings of the loch ness monster have been seen.
So no the Loch ness monster has never eaten anyone. Plus every year there is a monster swim in the loch ness bringing many people to swim and there has never been attacks or sightings.
I hope this helps you!!!