Is it ok to mix starch with fats? For example tons of butter on a sweet potato or pumpkin?
On one side, I've read that in the paleolithic world we would have never had such a quantity of starch/carbs with fat at the sametime and our body reacts adversely to this combination. On the other hand, I've read that eating fat with starchy vegetables helps blunt the insulin response from the starch.
I see no reason why a paleo person could not have gotten say some honey and some meat and eaten it at the same time, or some meat and some tubers, or some fatty worms and some fruit. I think that eating a lot of fat and starch together is probably helpful if you are trying to recover from heavy exercise or if you are trying to put on some muscle/pounds. It's probably not such a good thing if you want to lose weight. The sugar/starches raise insulin and the fat provides lots of calories for the insulin to put in storage. The sugar/starches may well also promote more calorie consumption and less satiation than would the fat alone (I have no research behind that last sentence but it's something I have defintely notices and research HAS shown that people tend to eat more if there is variety than if only one food item is present). This can be good if you need to eat more and/or put on weight and bad if you need to eat less and/or lose weight.
Saturated/monounstaturated fats and starch are fairly stable. I would worry more about mixing fructose with protein and/or unstable fats, but even that remains purely speculative. I also guarantee that there are plenty of easier fixes in your diet (and mine -- I ate 2 hamburgers + bun and cheesecake yesterday at a bbq...), so concentrate on fixing what you know is wrong and don't drive yourself crazy worrying about food separation.