Eating fat is now being reconsidered as the main culprit in weight gain, although it can be one of the contributing factors. I have a friend who recently lost over 30 kg in 3 months by deliberately eating a full fat diet. Upon his doctors advice, he now eats mainly lamb fat (the curly bit on the end of loin chops) fried chicken skins and gives the meat to his family preferring to eat only the fattiest parts. He makes special request to his butcher to sell him only the fattiest chops and keep the chicken skins for him. Just the skin and fat of the chicken. When cooking chicken dishes he always uses thigh and never breast. He cut out all carbohydrates and where possible, sugar.
He only eats the fatty meats, dairy, especially cheese, and obviously some vegetables and fruit. He did not change his exercise routine and actually has physical disability with his back that prevents most physical exercise. Incidentally he is 6'8" tall and was carrying a fair bit of weight but 30 kg is significant. I know he has continued to lose weight but I'm not sure how much in total now as I haven't seen him in 3 months or so but it would have to be up around 40 kg in 6 months by now.
I don't and never have avoided fat and I am not greatly overweight, and what I do carry can easily be attributed to a few too many cold lagers. Well ok, quite a few. Of all of my blood tests over many years my cholesterol levels are perfect and have never risen to a level that is even close to a concern. What is a liver?
Contrary to popular belief, fat is not the enemy. However, not all fats are good and my mate swears right off any oil that may contain GM material. He uses only olive oil, peanut oil and ghee and never processed vegetable or canola oils. I'm not as fussy as you can't really deep fry in either O/O or Peanut.
Properly deep fried food should not be oily. If the oil is the right temperature it will cook / seal the foods outside surface and then the cooking internally is from transferred heat, not oil penetration. This is why the best fish to cook is not oily fish. Oily fish allows the cooking oil flavours to penetrate and this is never nice.