The Myth of Target Heart Rate

The myth

It started decades ago, and some people still believe it:  If you want to lose fat you need your heart rate in the ‘fat-burning zone’ and for cardio health you need to be in the higher ‘cardio zone’.   Like all crap science, it sounds good but is wrong.

 I don’t know about you, but I don’t even really sweat when I am working out in the ‘fat burning’ zone. 

The science

There are no target heart rate zones.  Treadmills have those stickers on them because people want to see them.  They are nonsense and you can ignore them, with one caveat.  There are medical reasons to not exceed certain heart rates.  Ask your doc if this might apply to you.

 The thinking with this myth is that low intensity exercise burns fat calories and high intensity exercise burns carbohydrate calories.  Like many lies, it’s sort of true.  If your exercise is more intense, you will PROPORTIONATELY burn more carbs than fat.  However, the total number of calories is you burn is WAY higher if you are working out harder (higher heart rate).

Conclusion

Low intensity doesn't mean you only burn fat and high intensity doesn't mean you are burning all carbs.   You will burn fat and carbs in varying proportions, but the overall calorie burn will be higher when you work out harder.  Duh.  Working out harder will have a greater affect on fat loss than staying in some magical fat burning zone.   Your best measure on if you are working out hard enough is how you feel, not some arbitrary target heart rate sticker.