Are fitness trackers accurate for calories burned?

On Ep. 21, Nikkiey explains that the calories you burn during exercise are usually estimated from the type, intensity and duration of your workout, which is what heart rate monitors and activity trackers do. Those estimates rest on generalized equations, and everybody's metabolism is different. At most, she says, they tell you roughly whether you challenged yourself and got your heart rate up. Step trackers can help estimate everyday movement too, but it's hard to measure directly.

On Ep. 10 she is blunter: the calorie number on your watch or the cardio machine does not matter, because it isn't directly linked to your metabolism. The "I ate 1,800 and burned 600 on the treadmill" math is exactly the trap she fell into herself. She explains that repeating the same high-burn, low-muscle workouts teaches your body to adapt and conserve calories. Strength sessions may show a smaller number, but they build muscle, which she says is what helps speed up your metabolism and supports fat loss.

That's why a low reading after an arm day isn't a failed workout. On Ep. 282, Nikkiey points out that arms and shoulders are smaller muscle groups, so they won't burn as much as a leg day or a five-mile run. What matters is whether you pushed yourself and got stronger. She sees many women come to WarriorBabe stuck because they chased the tracker instead of their real progress.