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Should we be doing Gym Workouts fasted?

by Chris. Average Reading Time: about 8 minutes.

Musashi
Cronfeld

I am a huge fan of short intense body weight and aerobic work on an empty stomach in the morning prolonging the fast for about an hour after the session is finished. I feel these sessions burn body fat and they are a great start to the day. The sessions I am talking about are either short runs or body weight based met-con circuits like I mentioned in my previous blog post.

As well as this working out first thing in the morning is the best time to get workouts out of the way leaving the day free to live our lives.

What about longer resistance gym based weights sessions?

Maybe I am odd but I have tried to do heavy lifting first thing in the morning fasted on several occasions and have found that I feel very lethargic and weak, my lifts on compounds do not get near to the maximum weight I could lift. As well as this the workouts seem to affect my mood for days to come especially if I push too hard doing a Power Law Based training session.

From reading around I have come to the conclusion most people feel the same and to me it comes down to a few things;

  1. firstly our bodies are in a detox mode in the morning and more geared towards the ridding of toxins and therefore primed for aerobic activity which would include trail running, walking and high rep body weight work.
  2. If you have already fasted from say 6PM the previous evening and had a dinner based on wholefoods (Meat, Vegetables, Good Fat, Starch and Fruit) it is likely your muscle glycogen is very low-moderate which will stop you performing at your maximum level by the time you get to your workout at 8-9AM.
  3. Resistance work fasted hits your CNS harder potentially effecting your mood for days to come. Especially when done at High Intensity.
Martin Berkhan from leangains.com has a great insight on workouts when Intermittent Fasting:
Morning workouts and IF

I’ve been getting a lot of questions on how to structure meals in combination with morning workouts, without deviating from the plan; being that an 8 hour feeding phase is one of the fundamentals of the diet, morning workouts would have one starting the fast quite early, which for most people may feel a bit harder than fasting throughout the morning/lunch hours. Here’s what I’ve responded to a recent post, adressing my opinion on the subject matter:

Anyway, I am interested in your take on working out in the morning and how to fit that in w/ IF. I have been doing IF and feeling great but can only work out in the morning and, so take my post workout meal at that time. Is this ok, or what do you recommend?

“…for morning workouts, I usually recommend compromising a bit. The way I set this up, is to place a certain % of total calorie intake in an 8 hr feeding window pre-and post WO, and then “taper” calories towards the evening (high protein/low carb) in order to make a transition into the fasted phase (as low carb mimicks the effects from fasting to a certain degree). Thus, the feeding phase will be slightly longer than 8 hrs on workout days, but I consider this a good compromise in order to get proper PWO nutrition. Of course, one could go about this by initiating the fast in the afternoon/evening, but many consider this a bit daunting (and anecdtoally, fasting in the morning/lunch hours seems easier).”

Don’t feel your best working out with weights fasted?

If you must do pure strength and weights sessions on an empty stomach I recommend you try the following tips. They have helped me and from what I can gather helped others when doing AM workouts.

  • Have a piece of fruit before hand like a banana seems to do an amazing job at keeping our bodies in a negative energy balance whilst allowing you to perform well in the morning and burn fat. I have been experimenting with a banana and a shot of expresso pre workout (30 mins before) and it has been great, I suspect my insulin levels are kept low enough to encourage fat burning during the workout.
  • Try and do more light running/pushups/Pullups and squats first thing in the morning and fit in your gym based work in the evenings.
  • Experiment with Branched Chain Amino acids. I am not a huge fan of supplements like these but they will give you energy to get through workouts whilst keeping your body in a fasted state, 5-10 grams will do.
  • Eat dinner later at night. This is a tricky one as we want to go to bed with a somewhat empty stomach as to maximize growth Hormone release so be careful with this one, the main premise is to make the fast before the workout shorter but still be in a fasted state.
  • I will sometimes do fasted resistance work on mornings after cheat meals/dinners as I have normally eaten loads of high carb foods leaving me with plenty of muscle glycogen allowing me to steam roll through workouts, in spite of having fasted for several hours.

The take out point here is that everyone is different I know some people perform fine first thing in the morning whilst others suffer. If you are someone who does not fare well doing heavy resistance work while fasted then I suggest you experiment with some of the tips above and see what works for you or try and schedule your workouts to times you have some fuel in the system.

Update:

I had Kelly Frankson feature this article and make some very good extra points well worth checking out:

Some good take home points. I know everyone’s schedule is different, so here are some strategies to try to take advantage of a fasted state for fat loss (and muscle).

  • Try AM workouts fasted. Your liver glycogen is very low so you can get to burning fat quicker than later in the day. Do any strength training first and make it short and intense (under 30-40min). Or start off with some intervals for 10-15min (go hard/easy every min). You are trying to increase the GH output and deplete glycogen in that period.
  • Add some additional lifestyle activity after (cardio is the term I don’t like using…but that is what it is) a glycogen depleting workout. Hopefully you have gone at enough intensity to start freeing the fat from storage and now you have the ability to burn them in the muscle with no muscle loss. Go for a walk, bike ride, etc., nothing too highly strenuous otherwise you could be just wasting muscle, after your AM resistance/interval workout for another 30-45min (again this is now slower paced to take advantage of the fat burning environment you have just created)
  • Because the intensity at which people workout/do intervals will vary, many will need additional activity (aka cardio) to help burn the fat. Not everyone can just get superior fat loss on high intensity training only unless they can really push themselves to that level to benefit from the EPOC window of burning calories post workout. When in doubt, add in some more activity and burn that fat pwo.
  • If you workout later in the day, just try to eat as little as possible a couple hours before the workout. Remember that for fat loss we are trying to use weights and high intensity to drain glycogen and start burning fat afterwards.
  • Do not eat for an hour after your resistance/interval training (which includes the time spent doing the additional lifestyle activities pwo). So for example, if you do lifting for 30min, and then another 30min of walking…wait another 30 min before eating a meal of mostly protein and some fat/veggies. Don’t flood your body with sugar as that will just shut off fat burning for the next 3 hours. If you are feeling too low on energy (low blood sugar), then have some fruit pwo.
  • If you are feeling lightheaded or low blood sugar before a workout and can not do it, then you can add in some simple fruit 30min before to give you the energy to get through it (as we want our resistance and interval based training to be intense to get the full benefit)

Find what works for you and your schedule…and the fat should come peeling off little by little. Also a trick to add in some caffeine may help especially in the AM while fasted (as it stimulates a noradrenaline response to help signal those harder to burn fat cells with the A2 receptors…aka your trouble spots). Make sure you can tolerate it of course and take it slow and steady (may not be suitable for people with high BP or other issues, always check with a physician if you have any concerns). So to sum up:

  • Do Workouts (resistance/intervals) first and fasted (as much as you can)
  • Keep it short and intense for 20-40min
  • Keep moving at a slower enjoyable pace/activity following the resistance/interval session for another 20-40min
  • Eat protein/veg/fat pwo (60min after the resistance/interval part)
  • Eat fruit pre-workout if you can not do an intense enough workout fasted, or pwo if you are feeling too light headed and tired
  • Try caffeine pre workout (which can also increase intensity of workout and aid in signaling more fat loss…warning it can raise BP so make sure you are medically cleared for that first)
  • All workouts should leave you feel refreshed and still feeling great
  • Fat loss is an all day event, focus on eating for that hormonal response (no sugar, control insulin, eat slight calorie deficit for the day)
  • Slow and steady gets real results, burns the fat in the trouble spots and

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