Back in the 1960s, people started saying that eating foods high in saturated fat (like butter and meat) causes heart disease, but they didn’t have strong proof from real experiments—just some weak observations and loud opinions.

Back in the 1960s, some people started saying that eating foods high in saturated fat (like butter and meat) causes heart disease, but they didn’t have strong proof from experiments—just observations and loud opinions.

Back in the 1970s, scientists stopped taking seriously the idea that sugar causes heart disease, and some believe this was because food companies paid to make people think fat was the real problem instead.

People say this old study proved that eating fatty foods causes heart disease, but it only picked countries where both fat intake and heart disease were low—and ignored places where people ate lots of fat but still had low heart disease. That makes the conclusion unfair.

A famous old study that tried to link eating butter and meat to heart disease might have gotten it wrong because it picked countries in a biased way and asked people what they ate during times when they were fasting, which doesn’t show their normal eating habits.

Eating less saturated fat—like butter or fatty meats—doesn’t seem to lower the risk of dying from heart problems or other causes, even after years of doing it, according to a review of nine big studies.