Fat Burning Heart Rate Zone

The “fat burning zone” is zone 2: 60 to 70% of maximum HR — at age 30, about 114 to 133 bpm. At this intensity, the body uses proportionally more fat as fuel. But watch out: this doesn’t mean it burns more fat than more intense zones. Calculate your zone 2 by age below (shown highlighted).

Why zone 2 is called “fat burning”

At low to moderate intensity, the body can use fat as its main energy source. As intensity rises, it relies increasingly on carbohydrate, which is faster to access. Hence the nickname: in zone 2, the fraction of fat in the fuel mix is higher. The detail almost every ad forgets is that a high fraction isn’t the same as a high amount.

Fat fraction vs. total calories

	Zone 2 (60–70%)	Zone 3 (70–80%)
Fraction of fat burned	higher	lower
Total calories in the same time	lower	higher
Comfort / duration	high	medium

Zone 3 burns a smaller proportion of fat, but more total calories — and weight loss depends on total burn combined with a calorie deficit. That’s why there’s no “magic” zone for losing weight.

How to use zone 2 for weight loss

The real advantage of zone 2 is that it’s sustainable: you train for longer, more often, and with less wear, accumulating calorie burn over the week. A good strategy is to use zone 2 as a base (long walks, easy runs) and add zone 3 sessions to raise your total burn. The body loses weight through the whole routine — consistent training plus aligned nutrition — not by hitting the perfect zone on a single day.

This content is informational and does not replace guidance from an exercise physiology professional. See the heart rate by age chart and find out if a heart rate of 100 is normal.