Unsaturated fats on the other hand, while extremely important for the bodies natural function, are more detrimental when intake is too high. Basically these fats are primarily used for things like hormone synthesis and other intricate functions. Because of this the bodies fat storage cells, unlike with saturated fats, does not have an "off switch" for these fats. So in a normal functioning body, too much fat will cause a cell to go " ok no more" and send the fat elsewhere to be distributed across the body. However if the fat being stored is an unsaturated fat the fat cell will continue to grow and grow. Rejecting all other forms of energy for an overabundance of a type of fat it is also programmed not to use for fuel over other sources. And since these fats aren't used as a primary source of fuel they stick around longer. Not saying you can't burn them but the body sees them as vital and will avoid it if it can.

Then there's the issue of the body using the fats to build cells. All cells need fat to create their structures. You WANT saturated fat for this. Primarily because of it's rigid shape and lack of oxidizable double bonds. Like you state in the writeup concerning omega 3 supplements, oxidized unsaturated fats are basically "dead" but it's far worse than that. Unsaturated fats are PRONE to oxidation. This happens to the fats in the body as well. This is why antioxidants are so good for you and why "free radicals" are very bad. Free radicals oxidize unsaturated fats. If your cells are made of unsaturated fats they are in danger of oxidation which will harm and/or kill the cell. Hence why "free radicals" contribute to aging and antioxidants are seen as protective against aging. (This is impacting DNA as well) So now imagine what having a high intake of unsaturated fats does. It overloads the fats storage cells far past their capacity and then the use of the fats for structure leads to cells that are not only less rigid, something cells need for shape and function, but prone to oxidative stresses.

That being said, having too much of any fat is bad but being that the body is designed to primarily utilize saturated fats for fuel and cell structure you are far more capable of burning off an excess of that then unsaturated fats. Neither are bad. Both have an extremely important role in your body. But it is the ratios of those fats and overconsumption that you have to watch out for.

Going further into this, again, as you said about the omega 3 supplements being highly processed and getting oxidized... All processed seed oils, canola, corn, soy, grape seed, flax, undergo extreme processing similar to the processing that makes those omega 3 oils oxidized. The oils are heated repeatedly during this process, solvents used in extraction of even more oils and to "clean" them to remove the rancid smells that are produced from the process. All these things cause oxidation of the unsaturated fats. Then they are stored in clear plastic that does nothing to block any UV light, another thing that causes oxidation of the unsaturated bonds. By the time these oils hit the shelves they have been stripped of any protective antioxidants from the original seeds and turned into harmful, oxidated oils. They should be avoided at all costs.

That's not to say all vegetables oils are bad though. Quite the contrary. Olive oil, avocado oil, palm oil, coconut oil, are all cold pressed oils and very healthy. Even though all of those, save the coconut oil, are higher in unsaturated fats you also aren't chugging it down cause you typically don't fry things in those. Of course, if you are health conscious you should really avoid fried foods anyway. Additionally, being unprocessed, all these oils will have a great deal of their natural antioxidants I'm them. Further adding to their health benefits. Peanut oil is a different story. It CAN be cold pressed and ok for you similar to these others but it's never that easy. Many places (especially western manufactures) now will, in addition to pressing the peanuts, will also further process them similar to the seed oils which again, ruins the unsaturated fats.

I am not trying to come off saying avoid all unsaturated fats and chug a bunch of saturated fats. Only trying to bring to light misconceptions that were introduced nearly a century ago but seed oil manufacturers. Prior to the rise of crisco heat disease was so rare that the American heart association was all but pointless. A small, barely existent entity. Until it got a massive influx of money from the company that created crisco for the express purpose of promoting that product and demonizing saturated fats.