When Fat Burning is Really Not Fat Burning

Friday, December 21, 2018 · Mike Davis

Good morning!

Happy Winter Solstice, or happy first day of winter! This is one of my favorite days of the year, for one reason; we will experience the shortest day of the year and each one hereafter will get longer! Yay! Of course, in New Hampshire style, the first day of winter has many towns under flood watch because of all the rain ushering in this first day of winter.

I read an article the other day on cardio training in your fat burning zone. (running, biking, elliptical and etc.…) Many machines display diagrams with the low end of the zones displaying fat burning, or you can program in fat burning and the activity keeps you in a very low-level heart rate. Even some trainers use fat burning zone as a method of helping their clients attempt to lose weight.

The concept of steady low heart rate helping to burn calories is not inaccurate, however it is not affective. Whatever the activity may be, keeping your heart rate in a low zone, will have you utilizing fats as the primary source of fuel. So, on the surface low heart rate (minimal exertion), seems logical and even ideal for “fat burning.” In reality, the amount of activity required while working out in the fat burning zone is nearly 3-times that of the same activity in a more moderate zone. For example: You burn roughly 200 calories per hour running in the fat burning zone. If you run in a more moderate zone, for that same hour, you will burn 3 to 4 times that amount.

Fat burning is all about calories in and calories out. Staying in a low heart rate zone may not be any better than actually standing still. Both of these would require consumption of minimal calories to gain the deficit needed to lose weight. It is all about sensible calorie intake and metabolic activity. Tasking our body through activity, requires our body to tape into fats, carbohydrates and sometimes protein for fuel, the greater that activity stresses our body the greater the metabolic action (calories burned). In fact, as I have chatted about before and will emphasize in the future, the greater the continuous stress, the more calories we will burn post-workout. That is technically referred to as Excess Post-exercise Oxygen Consumption (EPOC). Minimal stress (low heart rate), minimal EPOC.

Before anyone thinks I am saying there is no value in easy steady state cardiovascular training, I want to quickly squash that. A workout should have a goal and if the goal is to improve cardiovascular health, or even an active recovery day, working out at a low intensity has much value. If the goal is actual fat burning, do not be taken in by low heart rate fat burning.

I will not share the link to the article I read as it was not particularly well explained, and it is really was not new information. Fat burning has been well understood in the exercise science world for some time, so the article was more just a good reminder. I hope this helps you as you plan your 2019 goals!

Hope you have a great first day of winter! The days are getting longer!!

God Bless!

Mike