Most of the old studies on cutting saturated fat were done on older men who weren’t taking cholesterol meds, so we can’t be sure the results apply to today’s diverse patients who often take medication to lower cholesterol.

When people took statins (cholesterol pills), cutting out saturated fat didn’t help them any more than just taking the pills alone — so the pills might be doing all the work, and diet changes don’t add extra benefit.

Some big studies that looked at lots of people who ate less saturated fat didn’t find that they lived longer or had fewer heart attacks, which makes people question why we’ve been told to avoid foods like butter and cheese for so long.

The studies that looked at whether cutting back on saturated fat is healthy are all kind of sloppy—they didn’t plan ahead properly, and none were done well enough to trust their results.

Even though people who ate less fat had much lower cholesterol, they didn’t live longer or have fewer heart attacks than those who didn’t change their diet.

Before the government told everyone to eat less fat, no study had actually tested whether eating exactly that much fat helped people live longer.