I am not a "health nut". Chaim would despise my diet. However, I do believe in trying to eat what G-d actually made for us instead of synthetics. Trans fats (hydrogenated oils) are petroleum-like synthetic lipids that the food industry loves to use because they are so much cheaper. Basically, you are eating Vaseline, and since your body has no way of dealing with it, it stays in your arteries forever, and causes widespread heart attacks, strokes, diabetes, etc.
I try to avoid trans fats completely. My favorite cooking mediums are butter, olive oil, and bacon grease (because of the taste). Otherwise, I use whatever liquid vegetable oil is around (not as tasty, but not unhealthy).