But what lesson can we draw from the cautionary tales of eggs and trans fats? We would surely be slow learners if we didn’t approach other well-established, oft-repeated, endlessly recycled nuggets of nutritional correctness with a rather jaundiced eye. Let’s start with calories. After all, we’ve been told that counting them is the foundation for dietetic rectitude, but it’s beginning to look like a monumental waste of time. Slowly but surely, nutrition researchers are shifting their focus to the concept of “satiety”, that is, how well certain foods satisfy our appetites. In this regard, protein and fat are emerging as the two most useful macronutrients. The penny has dropped that starving yourself on a calorie-restricted diet of crackers and crudités isn’t any answer to the obesity epidemic.
Let’s not jump so quickly to conclusions. As a commenter noted:
Conclusion from the abstract: Current evidence does not clearly support cardiovascular guidelines that encourage high consumption of polyunsaturated fatty acids and low consumption of total saturated fats.
Which is not the same as saying “now we reckon polyunsaturated fats are good for you”. It means, current evidence is (statistically) inconclusive.