In the latest development in the ongoing fat debacle, a massive new study in the Journal of the American Heart Association, finds that replacing saturated fats with unsaturated fats would do our heart health a world of good. In fact, eating more healthy fats, like omega-6 fatty acids, and fewer saturated fats and refined carbs could save up to a million deaths from heart disease per year, the authors calculate. In our scramble to de-vilify fats after they were cast away, en masse, back in the 80s, this new study makes a convincing case–not for putting fat back in the diet indiscriminately, but putting the good ones back, taking out the bad, and continuing to cut down on refined carbs and sugars.
(Photo credit should read MARK RALSTON/AFP/Getty Images)
The researchers behind the new study crunched nutrition data from 186 countries, which included some 3.8 billion people. They calculated how many heart disease-related deaths were due to eating too many “bad” (saturated) fats, vs. too little “good” (polyunsaturated) fats. Then they developed models to predict how many lives might be saved around the globe if people substituted the good for the bad.
They found that over 710,000 deaths from heart disease were likely due to eating too few omega-6 fats, which come from vegetable sources. Doing so contributed to an estimated 10% of the global deaths from heart disease. But only 3.6% of those deaths came from eating too many saturated fats, which are typically found in meat and cheese, and other dairy products. Confusing the situation somewhat is that they also come from palm and coconut oils, so it’s not quite simple as animal vs. vegetable. 
But this all suggests that we’re still hung up on the wrong message. “Worldwide, policymakers are focused on reducing saturated fats,” said study author Dariush Mozaffarian. “Yet, we found there would be a much bigger impact on heart disease deaths if the priority was to increase the consumption of polyunsaturated fats as a replacement for saturated fats and refined carbohydrates, as well as to reduce trans fats.” 
According to the study, another 537,000 deaths (or 7.7 % of the global deaths from heart disease) were due to eating too many trans fats, which are found in processed, baked and fried foods. Though they’re on the outs in Western nations, they’re still commonly used as cooking fats in some countries. And that needs to change.

“People think of trans fats as being only a rich country problem due to packaged and fast-food products,” said Mozaffarian. “But, in middle and low income nations such as India and in the Middle East, there is wide use of inexpensive, partially hydrogenated cooking fats in the home and by street vendors.” He adds that the deaths attributed to trans fats have gone down in the U.S. and other Western countries in recent years, due to public awareness of the issue, but they’re still growing in other countries. Similarly, the number of deaths from not eating enough unsaturated fats like omega-6s and from eating too many saturated fats has fallen in recent years–a good thing. But it’s still too high, especially in other parts of the world.
The takeaway is that putting heart healthy unsaturated fats into the diet, while simultaneously cutting down on saturated fats and refined carbs, is the most effective way. It’s not that “fat is back” or “butter is back,” as some have suggested–saturated fat may not be all bad, but there’s enoughevidence of its drawbacks that avoiding it is generally a good rule of thumb. But the idea that making substitutions where you can, choosing healthy fats over harmful ones, is better than trying to avoid an entire food group completely.
In any case, if you can’t remember what to do about fat, just remember this: Sugar is definitely out.