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Fasting while working out?

Hey all. I have been intermittent fasting (16:8) inconsistently for around 3 years now. I say inconsistently because I work in television and my shifts can be upwards of 18 to 20 hours at times; sometimes you just need food to stay awake. I make healthy choices, and keep the cheating to a minimum and only during extreme scenarios when I'm exhausted. When I'm between contracts (which I am right now) I get super strict with my fasting so I don't gain the inevitable 10lbs from the sudden lack of activity. I was super sloppy through the holidays, and I actually managed to gain around 15lbs, which I have been going to the gym to get rid of. I've been working out every day because I have nothing better to do, and I'm worried my muscles aren't getting the proper nutrition to ensure that what I'm doing is healthy. I'm a night hawk, so I typically don't eat until 1pm at the earliest, but I have been alternating light weight training with cardio every second day in the mornings. I just want to make sure I'm not hurting myself or my body by denying it nutrition before and after the workout. How do you guys manage your schedule? I just want to mention that adjusting my fasting schedule is not a great option because it always leads to failure for me. I'm usually up till 1-2am, so I need to be able to eat until at least 9pm to avoid going to bed hungry and restless.

Answer

FYI, this is a super frequently asked question (at least once a day). So you can see lots more discussion by searching the subreddit.

In general, though, the current thinking is that you don’t need to stress about eating protein right after a workout in order to build muscle. As long as you are getting enough protein overall, your body will know when to use it to build muscle.

This also goes for carbs. Your body will pull from its stored fuel (glycogen stored in liver and muscles, as well as fat) as needed to fuel a workout. You may not be able to achieve quite the same sprint speed while fasting, or one-rep max quite as high while fasting, as you could if you carb-loaded beforehand. But your goal is to lose weight and get stronger, not to win a competition every day. You’re still getting those benefits, even if your “fasting personal best” is a bit below your “carb-loaded personal best.”

TL;DR As long as you feel OK while working out fasted (not dizzy, sick, bad pain, or super-weak), then you are not hurting your body at all.

Answer

Obviously listen to your body (if it really hurts, if you feel faint, etc!), but plenty of folks myself included exercise in the midst of fasts. I regularly run 5-8 miles 20+ hours into a fast without issue, and have been for the past 6 months.

Answer

Daily protein intake, anywhere from 0.8-1.0+ gram per pound depending on activity and goals, is mostly what matters. It’s not like the body shuts off trying to repair itself just because it didn’t get a protein shake within 30 minutes of a workout. My two cents is that everything else is just grinding out those last few percentages - and some of it is just fitness industry nonsense - and matters for folks training for like the Olympics.

If your current method is working well for you, I see no reason to change it.