About a year ago, I increased my activity level significantly (distance running, hiking, strength training, cycling) and quickly found that:

a) I wasn't recovering quickly enough

b) It was extremely difficult to take in enough calories for a day in a single meal

c) I had very low energy when in ketosis

Eventually I gave up and just started eating on a typical 3-4 meal a day schedule. My RMR steadily increased back to baseline, I got a lot more explosive energy, my body began responding much more rapidly to training, and my recovery speed improved significantly.

Personally I think that intermittent fasting is not a good idea if you are very physically active. That's just my opinion from my own experience.

Did you experiment with any other patterns?

Don't be thrown off by the title. Yes, one group received testosterone, but even the placebo group that did not receive anabolic steroids, lost nearly 10 pounds of fat without losing any appreciable amount of lean body mass.

Dr. Peter Attia wrote about it in his newsletter this past week. [1]

Between my anecdotal experience of not feeling like I lose much lean body mass while fasting, this study above, and recent evidence from studies shown that "muscle memory", where a muscle can quickly regain any lost size it has had, is in fact real...I don't lose much sleep over losing muscle while fasting.

[0] https://www.sciencedirect.com/science/article/pii/S235239641... [1] https://peterattiamd.com/can-you-preserve-lean-body-mass-dur...

Nope.

I stopped counting macros and started eating just whatever again at the beginning of the summer and I'm slowly gaining the fat back. Unfortunately, there are no shortcuts (at least for me).

If you're focused on BF%, lifting is even more appealing since you'll be building muscle/reducing bf% even at a constant weight.

It sucked, it was hard (especially on a caloric deficit), but it worked.

So what happens? You lose muscle and fat in the same ratio? Or do you keep the fat?

There are people that literally just start skipping breakfast while keeping lunch/dinner/snacking the same. This is both technically intermittent fasting but also a reduction in overall caloric consumption. These people sometimes attribute their newfound weightloss to IF, when really they just started skipping a calorically dense meal every day.

For the past year, as an experiment, I've eaten carbs "normally" while doing 4x week gym. Few things I've noticed. My gut doesn't feel as good as it did while keto/IF, when you are in Keto and eat a cup of oatmeal ~45min before gym and start lifting you have this insane focus for the heavy 1-3 reps, I can seem to tolerate more better quality volume now compared to while doing keto/IF. But the overall feeling I have outside of the gym while not being in Keto/IF is a bit "sad", so most likely I'll start doing Keto/IF again to feel better. It's funny how insanely sweet strawberries taste while in Keto, and I kinda miss that feeling.

I personally found very hard already to progress on weightlifting during diet cycles, as I need to cut on volume significantly; can't imagine to do that while fasting, unless fasting would "flip a switch" in how the (my) body works, which I doubt.

Allow me to step right up.

First, as you might expect, aerobic and endurance exercise benefits greatly from being in a fasted (16-24 hr) state. You're light, quick and your body is devoting zero blood flow (and other resources) to digestion. I suspect you're not surprised by this.

Second, I do a 1.5 hour heavy leg workout which includes squats, deadlifts and other assorted "big" movements with weight that is significant, compared to my body weight. No issues at all. I wouldn't do this on a 24 hour fast, but it is my regular habit to do this workout while in a 16-18 hour fasted state and in general I have very slightly better results than if I had eaten recently. Again, the issue is the amount of blood flow (and other resources) your body is putting into digestion.

Finally, while it is easy and enjoyable to do my BJJ workouts in a fasted state, I cannot, then, do several rounds of sparring at the end without more recent calories. Or rather, I can but I after round one or two I am running out of gas.

YMMV. You should just try it. It costs nothing.

If that's true, why isn't it a universal practice in amateur and professional athletic competition?

(Or, for that matter, why isn't it banned?)

When you are right at the edge of your abilities being just a couple pounds lighter can feel like a world of difference (people hone down their rack to precisely what they need for a route, nothing more), especially on sport and boulder problems. My anecdata points to it being great for the project/performative aspects of the sport but as a tool for consistent progression/improvement, I am less confident in stating anything.

I'd say it depends greatly on the effort and the individual. Long, slow distance for someone who is accustomed to training fasted? Fat stores will suffice as an energy source.

But add in some intensity and that's gonna be rough without much glycogen in the tank - which will be the case if you've been fasting for the past 16-24 hours.

First, fasting does not require that your overall calorie intake is reduced. If your cut-goal is 2000kcal per day, you can fast in the morning and eat all 2000kcal in the afternoon. Ultimately, I find this is actually an easier and less hunger-inducing way to each your cutting goals.

Second, you're right. Doing weightlifting while fasted is hard. It's better to coordinate your gym schedule with your eating schedule so that you can eat -- I like a simple protein shake -- before and after the gym.

Third, I'm seeing a lot of folks talking about intermittent fasting ("IF") and day-long fasting in the same breath. I think IF is great for weightlifters on a cut diet. But I think day-long or multi-day fasts are different and should only be done occasionally (weekly being the most frequent) if you are trying to progress with weightlifting. YMMV.

The studies may not have been conducted among athletes so, testing your own body's response (by measuring lean body mass before and after a fast) seems like the best way forward.

I have read that people on keto diets or fasting have less "explosive" energy for workouts. I am not concerned that my body is going to cannibalise my biceps if I don't eat for a day or two. There is a lot more energy kicking around that is less important.

For me, it's worth it for the HGH boost: https://www.dietdoctor.com/fasting-and-growth-hormone

Gist of it is you still cut significant calories only eating like 500-800 a day in mostly low fat protien rich foods. Targeting only enough protien to avoid muscle wasting.

While I'm no doctor or nutritionist, my understanding is that it's for that case, you want some of the benefits of fasting like going into ketosis while maintaining lean mass.

Unfortunately I'm on my phone only this week so I can't try and find any studies about it, but I came across it first in connection with type 2 Diabetes. So you might have some luck googling those topics for more info.