I was asked about exercising while fasting by a lovely woman in our book club last night. It is a great question and something I was unsure about myself when I first started. You can absolutely fast while exercising and here are three of my top tips for making fasting while exercising easier.
1. Listen to your body
Often we have plans. A hike with friends, a hot yoga class to attend at 7:00, etc. And, those pre-arranged commitments don’t take into account how your body FEELs. Especially when you’re first starting with fasting, really try to listen to your body.
Some fasting days I will be craving intense aerobic exercise. On other days I’ll feel very lethargic and rest is what my body needs most. If you can, try to arrange your schedule so you have some flexibility to take into account what your body is telling you is best for you in this moment.
2. Take more water and electrolytes than you think you need
When I first attempted a 5-day fast I didn’t know enough about electrolytes. The first few days I felt great exercising while fasted. Then on the evening of Day 3 while on a hike, I was hit hard. I felt weak, sluggish and tired. I walked at half of my normal pace and I needed frequent breaks on anything steep. Despite drinking plenty of water, I just didn’t feel “right”.
I have since found that for me, taking a formulated blend of magnesium, potassium, and other key electrolytes + 2 tsps. of salt per day makes all the difference. The other half of this equation is be prepared to drink twice as much water as you normally would. When your body is in Ketosis from fasting, you need lots of water to metabolize fat cells and give your glycogen-depleted body energy. If you forget to drink water throughout the day or don’t have adequate water during exercise, it is going to hit you harder than it would on a non-fasting day and frankly – you’re going to have a bad time.
3. Build-up slowly
When you’re first starting fasting, I think it helps to take a step back from exercise and really dial your fasting in. Once you feel confident in the fasting then slowly add back in exercise. Start with a yin yoga class or a light jog. Let yourself acclimate to using body fat for fuel vs. food you’ve consumed earlier in the day.
I started back at about 25% of what I would normally do. Gradually I’ve worked myself up to 75%. Everyone is different, though, and you have to find what works best for you. There are now endurance and elite athletes that are training in a fasted or ketogenic states, because it is such a powerful tool.
See a few examples here:
Or if you just need help looking more athletic than you really are, I’ve got you covered:
I’m curious to hear from you! How do you feel about exercising while fasting?