If you’ve been scrolling Instagram or listening to workout podcasts lately, you might’ve heard the term “Zone 2 running.” But what is it really — and why are so many athletes and coaches buzzing about it?

When people start thinking about nutrition — especially around fitness and dieting — one macronutrient tends to get applauded and the other unfairly blamed:

Staying the same feels safe. Familiar. Neutral. When nothing is actively falling apart, it’s easy to believe that no decision is a decision—that holding steady comes without a price. But it does. It just doesn’t send an invoice right away.