I am a competitive olympic lifter. I train about 10 hours a week, in a 5 day program. I am currently about 25% body fat.
When I was around 30% body fat, I tried a 7 day fast, maintaining my training regimen. I don’t know how extended you are looking for, but I can give you my recollections.
The primary goal in olympic lifting is power production. You are trying to lift as much weight as possibly as quickly as possible. Additionally, there is a neurological load. You must focus because you are, in all three movements, under a very heavy bar. I am still alive to write this, that should give you a hint as to the outcome.
During the fast I consumed about 3g to 4g of sodium a day (in the form of brine). Additionally, I concocted a sports drink specifically for fasting (1/4 cup ACV, 1tsp pink salt, 1tbsp granular swerve, 1/2tsp guarana powder, fill to 1L with water) that concentrated salt delivery during the workouts.
What I experienced, in general, was that everything was basically exactly the same. To be clear, I am not an elite lifter, I do not know if this approach would necessarily apply if I was suddenly capable of lifting 100kg more than I do now. What I do know is that power production did not decrease, in fact, I set a PR on one of the days. Neurological function did not decrease, I never felt like I was dizzy or anything like that, nor did I feel like my gross or fine motor skills deteriorate, or develop any sort of shakes, like in a hypoglycemic state.
This seems to contradict the commonly held notion that fasting would interfere with muscular workouts (especially olympic lifting) due to the requirements of ATP replenishment that typical fat metabolism (and even anaerobic metabolism) is too slow to accommodate. This does not seem to line up with my experience (yet?). Additionally, there has been evidence that fasted/keto marathon runners are able of metabolizing fat at higher and more continuous rates than was previously believed to be possible.
In concession, the most prominent “negative” thing I experienced was a marked adrenal response after some lifts. At this point, I hypothesize that it was my body attempting to ramp up glucose conversion and fat production through hormonal upregulation so that I could recover between lift attempts. Since working on my conditioning, this seems to be less prominent now.
As I have lost fat, I have found that I have what I think is mild vagus nerve stimulation causing me to feel mildly faint during a clean recovery. However, this seems to be the same in both a fasted and non fasted state.
Additionally, as my fat came down, I switched coaches. The second coach put me on a very aggressive program, and I started to experience some low mood during that transition if I fasted for more than 24 hours (after workouts, performance during workouts was unchanged). However, I have recovered a bit from that program and will probably soon try another 48-72 hr fast to test the waters with that.
Obviously this is not a blanket endorsement to fast and workout without assessing your own unique condition, or if you don’t know how, without getting a doctor’s advice who specializes in fasting (such as Dr. Fung, incidentally Angel Ramos is my fasting coach through IDM). But it is possible, and when managed properly, doesn’t detract from performance as far as I can yet tell. However, you definitely need to stay in tune with your body throughout and keep notes or tabs or something to make sure you don’t lose your perspective and wander into any sort of dangerous territory.
