actually Jens, I think you picked one of the few bad examples for that, I will blaming on your anticipation for the steak tonight. A lot of people here mix flax and oats (I for sure do, not really a problem)
Low GI carbs (hell, even medium GI carbs) or fibrous carbs are OK with good fats (think, Green salad with oilve oil???)
High GI carbs, paired with SHITTY fats (or even good fats) are a no-go (think donuts: flour, sugar and deep fried).
the science behind it? you spike insuline with the carbs and the fat takes a free ride on that spike