Okay so Paleo-ers are well aware of both dangers but which is worse: PUFA's or Grains/Fructose? Which seems to have the biggest negative impact on your body, or based on the literature? Trans fats are obvious, I'm talking mainly about the bad fats from canola/soybean/corn/peanut/other veggie seed oils.
I'm starting to think PUFA's are worse because they personally feel easier to overeat (our taste buds didn't evolve for them), cause inflammation/clogged liver, often replace the good fats in our diet and oxidize easily in the bloodstream, if the rancid oils haven't already done so. I have also read studies showing that alcohol wouldn't cause liver cirrhosis/fatty liver had we replaced PUFA's with saturated fats. Seems pretty evil to me. I also feel fine occasionally eating sugar/grains like ice cream or baked goods but it seems now each time I consume a considerable amount of vegetable oils, I get very tired soon afterwards, a sign of inflammation. Its almost like my metabolism slows down.
I think if were talking from a Paleo perspective then grains are the worst offender in my opinion. I would rather see someone eat lots of fruit, nuts, or other foods that contain higher amounts of PUFA/Fructose then a piece of bread.
If were throwing Paleo out the window and talking cheat foods then I think it really starts to vary from person to person. I personally do okay with extra sugar or grains but something fried in vegetable oil can sideline me for days. But I also think it would be safe to assume that someone with Celiac would do worse with the grains and someone who is struggling with weight issues would struggle the most with excess sugar.
What's more relevant is what to include, not what to exclude. Hunting and gathering is first priority. Eating meat is second. Being social - tribal - is third. Food exclusion comes way down the list. I put PUFA and grain exclusion in a tie for #44. Fructose exclusion comes in at #109 since paleos ate it.