Does Your Body Burn Fat Or Muscle First When Fasting?

Have you ever wondered if we Burn Fat or Muscle first when Fasting?

We have been doing some recent experiments with fasted hiking and the results have been good so far. However, one area that I am a little concerned about is that I don’t want to lose too much muscle mass.

I haven’t shown any concrete signs of muscle loss to date, but maybe that is too be expected with only completing a couple of fasted hikes. I have noticed that my hiking friends that have been fasting for a long time have a lot less muscle than me. Is there a correlation because of the fact that they fast here, or is their lack of muscle mass just a coincidence? Let’s dig a bit deeper to find out.

When Fasting for over 12 Hours, which is Burned First, Fat or Muscle?

The clear answer here is Fat. It appears that it is almost impossible to find any evidence that your body will start to burn any muscle whatsoever if you are intermittent fasting. Certainly not if you are only fasting for somewhere between 12 and 16 hours at a time.

The whole reason that your body stores fat, is so that it has an “on demand” store of energy to call upon when your Glycogen is depleted. Why would it burn muscle and potentially damage the structure and integrity of our body if it wasn’t in a life or death, survival situation, which intermittent fasting for short periods of time is not.

However, at around the 12 hour mark of fasting, if we haven’t been exercising (sooner if we have), our body will begin to burn fat as our Glycogen will be depleted. Read more...