Honestly, I’m really curious about the fasting protocols biohackers use. Fasting is probably the hardest thing to stick to on the longevity journey, so I’d love to hear everyone’s stories.
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I am not sure I’ll do it this year, but since 2020, I’ve done Prolon 12-14x.
I find not having my morning latte is torture, but other than that, I think it’s fairly easy to do… at least after the first round.
I doubt I could ever do a true fast, even for only 24 hours… too stressful for me… and yeah, I know that’s the point 
I don’t eat at least 12 hours a day because I feel better doing it, but that is obviously not a fast.
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I am currently fasting monday, Wednesday, friday by default.
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I have tried up to 3 day fasts. It gets harder in day 3, but the first two days are easy.
So, I am hoping the effects of rapamycin are close enough, so I avoid fasting now.
I am currently trying semaglutide oral and it’s similar to fasting, or at least caloric restriction. It’s also so.much easier… No hunger pains (which admittedly go away after the first day and n the fast, but then day 3 I have very low energy).
So, sorry, no solution for you.
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I have also done Prolon several times, but tire of the nut bar and some of the soups. I have also tried to create my own FMD using foods similar to Prolon and similar calorie totals. The effects have seemed similar. Straight fasting or just water is too hard for me to take. Even eating just a small bit helps .
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I’ve been doing TRE (16:8) for many years by simply skipping breakfast. It takes me virtually no effort anymore — my body is completely used to it.
About 4 years ago, I also started skipping dinner every Tuesday, resulting in a weekly 24-hour fast from Tuesday lunch to Wednesday lunch.
I exercise daily and usually do an endurance workout on Tuesday afternoon (typically a 2–3 hour bike ride) to amplify the metabolic effects of fasting (autophagy, glycogen depletion, etc.).
Skipping Tuesday dinner still takes a bit of willpower because I feel hungry between roughly 5 pm and 7 pm, after which the hunger fades again.
One interesting thing: that night I tend to feel colder than usual. I normally sleep naked, but in the 24-hour fast I often wear socks and a T-shirt because my feet feel cold.
Oddly enough, I also feel at my best on Wednesday morning: mentally very clear, energetic and physically strong.
My body weight fluctuates during the week:
- 71–72 kg on Wednesday morning
- 73–74 kg by the following Tuesday morning
I’ll turn 65 in a few months.
Body fat: 11.5%
VO₂max: 52
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I would be concerned about fasting too long as the body does not really have a reserve of amino acids so starts recycling protein such as muscle mass. I stick with day long fasts (which end up as from 6pm on one day to 6am two days later ie 36 hours. That is because that will put the body into a more catabolic state without the catabolism being too much protein orientated. I also start the day at 6am with some cheese because that contains protein.
I tend to feel a bit cold when fasting. I think the body turns down the volume.
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I skip breakfast too (last 3 years or so) and have had a similar experience. I have no hunger until about 11 am when I habitually have my early lunch. Having already habituated over the last decade to eating earlier in the evening with my kids.
I wonder if its only easy because im working with my Chronotype… I’m not a morning person, and have hated eating too early since teen years. For “larks” i wonder if it’s easier to stop eating earlier in the evening?
Extending to a 24 hour fast would take a lot of willpower. But my diy prolon-inspired fast-mimicking diet was “relatively” easy for the first 3 of 5 days - mainly, i think, because the diy soups were so delicious.
But I’m not sure what the costs/benefits of 5 days of fmd are compared to rapamycin?
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I gradually increased my fasting to around 20 hours ve a day five years ago, which I have stuck to since then. No or little hunger, I ignore those signals I think my body has adapted . Automatically gives me a mild caloric restriction and with the foods I choose it becomes CRON.
One main meal per day with a kilo of 20 kinds of veggies, 300 grams of fat fish mainly herring, 200 g beans. With much olive oil and a ten-spice mix it tastes fine. A couple of hours later dessert with berries, nuts, seeds, yoghurt, avocado.
Keeping to the same timing, I go to all-you-can-eat buffet restaurants, mainly vegetarian, a couple of times per week
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I love food and this lets me gorge every day. On top it saves a lot of time.
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I don’t do it at all. I’m not convinced there are any real benefits, especially at my age (40).
I have done 72h or 96h water-only fasts before, and I am not convinced that it was worth it. The hunger itself doesn’t bother me, but I felt generally bad and stupid. People say you’ll get all this energy from ketones, mental clarity etc. Nope - I just felt like a zombie the whole time. Exercise tolerance was terrible. Definitely lost muscle doing it. Made family time feel like a real struggle, and was hard to explain to my young kids while trying to encourage them to follow regular meal times.
I’ve done Prolon once, and didn’t like it. I also tried time-restricted eating, and again just didn’t really feel or measure any benefit.
I am fairly convinced that this is a highly-individual thing. Some people are comparatively not bothered by eating or fasting, and other people literally can’t skip a single meal. My wife HATES fasting, and she kinds grazes food all day. But her body weight is stable to within 2kg of when I met her 15 years ago and before our two kids, and she’s arguably fitter and has better body composition now. Blood biomarkers are incredibly good too. Both of us have HBA1C of below 5%. If there is anything happening during fasting like autophagy, that’s speculative and not measurable.
Nowadays, my priority is a generally “healthy” and balanced diet with an emphasis on maintaining my weight, body composition and other biomarkers. I don’t usually have “breakfast” but I make a blended shake with a bunch of vegetables, berries, yoghurt, nuts, seeds, fibre, probiotics etc. Tasty, 30g protein, lots of fibre, lots of micronutrients.
Dinner is nothing special - sandwiches, pasta, pizza, risotto, steak, roast chicken etc, with wife and kids. Make sure to get my 5-a-day of veg and fruit. There are always plenty of fruits and veg available. I don’t say no to ice cream, the occasional cake or chocolate brownie etc. I supplement ~50g of whey protein per day, mostly in the periods after exercise. I have had no problem keeping a target body weight within ~2kg, and I have no problems gaining or losing as I wish. If I’m getting too heavy, I turn my lattes into americanos, which cuts ~300kcal and the weight comes down.
The only “rule” I follow is to avoid eating soon before bed, and especially not eating junk before bed. Sometimes I’ll have a protein shake before bed, if I’ve had a tough workout session.
As far as I can tell, the main issues with people’s diets are the overall calorie balance, and getting enough protein, healthy fats and micronutrients. Obviously, most people in the general population over-eat and carry excess weight, which is detrimental. So the biggest benefit, IMO, comes from simply not doing that.
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One reason I am doing alternate day eating is that it enables me to have a bit of a binge on eating days and also I am able to reduce my weight gradually. I am not massively hungry on fasting days, but I can always tell myself I will eat the next morning.
I only do one day, however, as I think the challenges to lean mass would be an issue.
On the issue of metabolism and autophagy I do note that I am significantlly more metabolically active when asleep on a fasting day than on an eating day. Measured by movements in heart rate.
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Totally agree on this being individual. I am not a faster. I’ve done TRE and even after months, it wasn’t natural.
I have a pretty strong hunger drive. If I restrict significantly, I will wake up at 2 am hungry and can’t return to sleep without eating.
While I fully understand that our hunger issues change based on habit, I haven’t ever overcome it. I mean I can, but sleep suffers and I get slack for being too skinny by my wife.
100% our metabolism reacts to caloric load so you will feel cold with less calories. Some people (me) find this very noticable. And there is definitely a point where you can’t recover the metabolism like a habitual dieter. Probably good for longevity but you will be cold and never able to eat more calories without gaining weight.
What I like about Rapa is I figure that I can stop trying so hard to fast.
My wife does TRE and has for 5+ years and it works well for her.
I do like the feeling of a good HIIT workout while fasted. This is something I could get behind like once a month.
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I have done TRE in the past, and a few couple-days fast. But now I am 76, BMI19 and 22.6% body fat. I need to optimize for building or at least maintaining muscle. So the only time I restrict are the two days that I swim early: nothing from 8 the night before til noon the next day. (Rarely eat after 7- 8.) I have found in the last few years that, as I have now been consistently going to bed earlier, I am hungry only in the first part of the day. By dinner at 4PM I am not really hungry. So, my “timing” focus has been to re-align getting nutrients earlier and reducing the size of dinner. That seems to work best with my natural rhythm.
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I did fast in the past - even 3 day water fasts were easy. Now I’m 71 with BMI 20.5. Each pound counts. My diet is CR (plant based and kidney oriented) and I eat in 8-10 hour window. My muscle tone is still OK.
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I used to fast, but over time I’ve found it increasingly psychologically harder to do. I don’t think I will ever fast again voluntarily. For me, the mtor inhibition from GLP1s and rapamycin is good enough.
Ive always assumed middle age is the best time to fast - I just asked claude and …
“Middle-aged and older adults (roughly 35–65) get the clearest benefit” and
The strongest RCT evidence targets metabolically unhealthy midlife adults (50–75 years) with overweight/obesity and prediabetes or T2D (PubMed:Time-restricted eating to improve cardiometabolic health: The New York Time-Restricted EATing randomized clinical trial - Protocol overview - PubMed
I’m metabolically healthy.
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Yes, I wouldn’t fast or TRE with your BMI and metabolic health.
Personally I’m probably running a bit “hot” and feel like I benefit from periodic catabolism!
I think fasting has benefits in the sense of encouraging autophagy even if someone has a lowish BMI and good metabolic health.
You’re absolutely right. I was thinking of the net benefit - and assuming that fasting at that age and BMI has its own (mainly sarcopaenia?) cost, and that one might therefore rely solely on rapamycin for mtorc inhibition/autophagy.
BUT your posted triggered me into looking into what fasting adds (over and above rapa): per claude:
“Rapamycin is a partial mTORC1 inhibitor. It allosterically inhibits mTORC1 via FKBP12, but incompletely — particularly for some substrates like 4E-BP1 (translational control). It doesn’t fully replicate the nutrient-deprivation signal. Fasting suppresses mTORC1 through multiple upstream inputs simultaneously: absent amino acids (Ragulator/Rag GTPase pathway), low insulin (PI3K/Akt suppression), and rising AMPK — a mechanistically broader hit.
AMPK activation requires an energy deficit. Rapamycin doesn’t raise AMPK. Fasting does, via falling ATP:AMP ratio. AMPK independently drives autophagy (phosphorylates ULK1 directly) and is additive with mTORC1 suppression. Your berberine covers some AMPK territory daily, but fasting is a stronger acute stimulus.
Lysosomal biogenesis and TFEB. Fasting activates TFEB (master regulator of lysosomal and autophagic gene expression) via mTORC1 dissociation from the lysosomal surface. Rapamycin does this less robustly — the spatial/physical context of nutrient sensing at the lysosome matters, not just kinase inhibition.
Mitophagy specifically. PINK1/Parkin-mediated mitophagy requires mitochondrial membrane potential depolarisation and upstream signals that fasting amplifies beyond what rapamycin alone provides. The evidence for rapamycin driving mitophagy directly is weaker than for general autophagy.”
You could replicate some of this with Berberine/Metformin (AMPK), Spermidine/Wheat Germ ( TFEB)
Pomegranate Peel Powder/Urolitnin A (PINK1)
I extend my overnight fast (up to 20 hours) on rapamycin days and hope to get the biggest bang for my fasting buck. And this might well be the best strategy even with a low BMI and no metabolic issues
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