The Hidden Truth About ‘Fat-Burning Zones’ at the Gym
Walk into any gym, and you'll see charts on cardio machines pointing to a "Fat-Burning Zone," typically defined as 60-70% of your maximum heart rate. The theory is seductive: work out at a lower intensity, and your body will burn a higher *percentage* of calories from fat. While this is technically true, it's a misleading and incomplete picture that can actually hinder your long-term fat-loss goals.
The Science of Fuel Sources
It's true that at lower intensities (like a brisk walk), your body can use oxygen to efficiently break down fat for fuel. At this pace, fat may supply up to 60% of your total calories burned. As you increase the intensity (like during a sprint), your body needs energy faster than the fat-burning process can deliver. It then shifts to burning a higher percentage...