I’ve been keto for 6-7 months and have just recently started fasting - a 30hr and 80hr completed, and I started another on Sunday evening. It definitely gets easier.
I swim most weekday mornings, between 1000-1500m each time, my 100m average time is the benchmark I look at to see if I’m improving. My three fastest times have been while fasted, the quickest ever this morning - what’s going on here? Can anyone explain why this should be? Thanks
Your body wants you to catch some fish, its hungry!
This is one of these things that make sense theoretically but are still mindblowing once you actually experience it.
Yes it makes sense that your body would increase your metabolism / performance to help you catch some food, but when you break a Deadlift PR after 4 days of not eating, simply because it felt easier, you still have a hard time grasping it.
I’ve heard it called “The Hunters High” - a few physical, cerebral, sensory enhancements that increase the likelihood of your catching food.
Your body generates Human Growth Hormone which will lead to muscle gain during a fast. It also doesn’t have the overhead of processing food while you are fasting. So, you be at your fastest during the mid to end of your fast.
But, don’t take my word for it. That is just what I’ve noticed.
I remember seeing some graphs several years ago that showed the metabolism/adrenaline boost lasted around 3 days - if they’re related, and I suspect they are…then that would be a good first assumption.
It would be interesting to see if this extends with frequent practice or whatever. The vast majority of my fasting has been ADF…the thing I don’t like about ADF is that you quit just as it gets started…you wake up after a fasting day feeling fantastic, but then you eat and it spoils it - but then I never combined ADF and keto…I’m personally wondering if you can control, or at least accurately schedule the performance boost.
I’ve always wondered how effective the HGH actually is for muscle gain during a fast. I know that normal protein turnover decreases somewhat…but with no incoming protein with which to fashion new muscle - especially if you’re training and accelerating the breakdown…I wonder if the HGH works more in a preservation and fat burning capacity.
At this point I’ve heard folk mention autophagy - the implication that the process scrapes together enough amino acids to be used for the muscle growth…but, I mean, how much amino acid is actually produced…not only to overcome turnover…and exercise damage…but also muscle growth…as well as non-muscle regeneration.
Many supporters of fasting say “no, no…muscle is preserved during fasting”…and yeah, I get that…but for me it misses the point in the context of someone who trains.
I’ve never seen any data or study of these things in real terms.
I only have an n=1 here.
I gained 1.6 KG of Lean Body Mass (probably muscle) and lost 5.8 KG of Fat on an 11 day water fast. I had a DEXA taken the morning I started the fast, and I had a second DEXA scan taken the morning I was going to end the fast.
My main form of exercise was 5 minutes of lifting weight; something I never did before.
So, I must have turned over some proteins…
As usual though; individual results may vary.
Interesting…5 minutes a day with no prior experience? Did you target full body or specific muscles?
There is a phenomenon known as newbie gains…such that at the onset of training muscle develops very rapidly…often at the same time as rapid fatloss…
I wonder if the new training stimulus is enough to prioritise growth even when fasting…I could certainly see the survival benefits.
When ADFing and training I find that my body just can’t keep up after a while…get tired and everything hurts. In some ways this is why I’m interested in keto…to try and find a way to train at the level I like, whilst also losing a bit of fat.
I’ve heard that a day or two fasting a week can prove to be beneficial though…as it helps control inflammation etc…
Since I normally rode bicycle, I decided to target the arm things.
I just went in and picked up dumb bells (not politically correct) or free weights and just lifted them in what I believe is a Hammer Curl (I had to Google it to even know what that was).
But, I really have no idea what I’m doing with it.
Hahaha - the majority of people in the gym have no idea what they’re doing either 
Dr. Fung talks about this in the fasting guide book. The counterregulatory hormones, HGH, cortisol, glucagon and adrenaline all rise around dawn. So the adrenaline is higher and that would give you the opportunity to improve any physical activity.
My guess is that you have more energy in your inventory with fat than you do with glucose in blood/tissue. So, if in ketosis, you are burning fat the whole time. You say you are at a fastest average pace for 100 m (which takes into account how much endurance you have over the long span of 1 to 1.5 km swimming). There’s a big difference measuring speed of a 100 m “sprint” versus average speed over the distance of 1 to 1.5 km. Someone without the endurance can excel at 100 m, and then bonk at extended lengths.
I’ve seen similar results while fasting. I think, like Tom said, it’s a combination of HGH levels AND “excess energy” left over from NOT having to process food (digesting food requires a metabolic “payment”). The way I understand it, the less you eat (over a period of time) the less “stress” on the body from digestion/dealing with the post-effects of food ingestion, leading to possible longevity improvements. In the short term, working out fasted keeps me feeling more alert and energetic.
I broke my fast last night, late last night in fact. My swim this morning was noticeably more lethargic
Isn’t the body amazing? We are led to believe that we “need” food in order to survive, the TV screams “eat every three hours or you’ll die!” our Mother’s tell us “you need to eat!” and society, in general, is simply fascinated/enamored with food. When you are fasting you “see the matrix” of food advertising/sells/etc.
Your experience tracks, I often feel less energetic after eating, doesn’t that counter conventional wisdom? I’ve seen other “abnormal responses” like gaining weight 5-6 days into a fast (water weight from changes in stress levels and electrolyte intake… etc.).
That’s a good N=1 data point you have now, something to use in the future. Maybe fasting is the preferred method of achieving top performance? The question is, how long to fast before trying to set a PR, what’s the “best” relationship?
I just finished my first fast earlier this week. Approximately 36 hours. The 2 days after fasting impressed me. I was down another 2 pounds & down 2% on body fat (according to my Aria Fitbit scale). It wasn’t as hard as I thought it was going to be. I will definitely do again when I stall.