[DanBC]

The Google Instant answer for the question [does butter contain trans fat?] says 100 g butter contains 3.3 g of trans fat.

http://imgur.com/a/i7qw0

Trans fats sometimes occur naturally in food. They're created by bacteria in an animal's stomach.

Trans fats were nothing to do with weight loss. Trans fats were used because they're cheap and have long shelf life.