For generations, the low-fat dietary commandment stood as settled science — a clean equation where saturated fat equaled cardiovascular harm. Now, research from the University of Toronto quietly dismantles that certainty, finding that full-fat dairy consumed daily produced no measurable harm and, in some cases, measurable benefit. The story is less about dairy's rehabilitation than about science learning to see food not as a list of ingredients, but as a living architecture of interacting systems.