Scientists aren’t very confident in what they know about how saturated and trans fats affect health — more research could easily change what we think today.

We can’t be sure if saturated fat is good or bad for you because the studies are all over the place—some say one thing, others say the opposite, and the measurements aren’t very accurate.

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.

Eating more saturated fat from butter, meat, or cheese doesn’t clearly make people more likely to die early or get heart disease or diabetes, but the studies aren’t perfect, so we can’t be totally sure.

There isn’t strong enough proof to say that eating less saturated fat and more vegetable oils will definitely prevent heart disease, according to this big review.

Even when researchers accounted for how many total calories people ate or how much other fats they consumed, the link between saturated fat and heart disease still didn’t show up.