Fat-loss running
What Is the Fat-Burning Zone in Running?
The fat-burning zone is real physiology, but it is easy to overread. Low to moderate intensity uses a higher share of fat, while fat loss still depends on long-term energy balance.
The simple idea
As exercise gets harder, the body shifts from using more fat toward using more carbohydrate. This is often called the crossover concept.
What FATmax means
FATmax is the intensity where fat oxidation is highest for that person. For many runners it sits near easy aerobic running, but it varies by fitness, sex, diet, and training history.
Why easy running helps
Easy running lets you accumulate time on feet without exhausting recovery. That repeatable volume is more useful than one heroic hard run.
How to find it without a lab
Use a talk test: you should speak in short sentences, breathe steadily, and finish feeling that you could continue. Heart-rate Zone 2 can support this, but it is not a magic boundary.
The common mistake
Do not chase the lowest heart rate or avoid all faster work forever. The goal is a sustainable base first, then small doses of harder training when your routine is stable.