Zach Bitter ran 100 miles in 11:19:13 on a low-carb diet averaging ~6:47 per mile — doing it well below his aerobic threshold — while the conventional recommendation for ultra-racing is 60-80g carbs per hour; his approach is nutrition periodization matched to training intensity, not a blanket rejection of carbohydrate.
2
The key periodization insight: match your fuel to your training phase. Strict keto (under 50g carbs/day) on easy and rest days; up to 300g carbs on VO2 max interval days. Protein stays constant at roughly 1g per pound of bodyweight throughout.
3
Mental training is as structured as physical training: during 3-4 hour long runs, Bitter visualizes specific race-day scenarios — the hard spot at mile 70, the late-race progression — so that on race day the right response is automatic, not effortful.
4
Recovery has three equal pillars — nutrition, training input, and recovery itself — and within recovery, sleep quality beats every modality. Tools like red light, cold-hot contrast, and circadian light exposure matter primarily insofar as they improve sleep, not independently.
Protocols
Concrete recipes — what, when, how much, and why
8 items
Carb periodization by training day: keto on easy days, up to 300g carbs on interval days
WhatMatch daily carbohydrate intake to the glycolytic demand of that specific training session. On rest days and easy zone 1-2 runs: strict ketogenic (<50g carbs). On VO2 max or lactate threshold interval days: add carbohydrate from sports products (gels, sports drinks) before and during the session, up to 200-300g for the day.
WhenApplied continuously across the training year. Phase context: offseason ~5% calories from carbs; base building ~10% (100-150g); speedwork development phase up to 15-20% on hard days.
DoseEasy/rest days: <50g carbs. Long run days: ~200g. Hard interval days: up to 300g. Protein constant at ~1g/lb bodyweight throughout.
For whomLow-carb athletes trying to maintain fat adaptation while supporting quality high-intensity training. Also useful for any athlete who notices quality degradation in repeated interval sessions on a fixed-macro diet.
WhyFat oxidation handles zone 1-2 work without carbohydrate. Glycolysis is rate-limiting for VO2 max intervals and repeated hard sessions. Providing carbs only when the glycolytic pathway is being taxed preserves low-carb adaptation while removing the performance ceiling at high intensity.
CaveatsRequires tracking — Bitter uses apps to monitor macros. The model may not work for shorter-distance athletes who race at intensities requiring full glycogen availability throughout.
Bitter observed the telltale sign of inadequate carbs for interval work: lap splits that were 3-4 seconds per lap slower at the same perceived effort after several weeks of strict keto intervals. One session was fine; weeks of stacking them degraded performance. The fix was targeted carbohydrate — sports gels before and during interval sessions only — which restored split quality without abandoning low-carb during the remainder of the week.
I sort of like just got rid of the idea of like this thing resets every 24 hours and started thinking of it as like how do I maximize the fuel source for the work I'm doing so if I had like an easy run or a rest day I might stick to that stricter ketogenic protocol and have very little to no carbohydrates on a day like that so that would be 50 or less yep and then I might be doing short intervals on Tuesday and Thursday so I might have sometimes two I've had days where I've close to 300 gram of carbohydrates on days like that
Race-day ultra fueling: 60-80g carbs/hr, 75-85% of intake from carbs for single-day events
WhatCurrent ultra running position statement: 60-80g carbohydrate per hour during a single-day ultra event (the field is skewing toward the high end). Macronutrient mix for single-day ultra race day: 75-85% carbohydrate, 15-25% blended fat and protein. For a fat-adapted athlete like Bitter, this means using sports gels and drinks specifically during the race as the primary exogenous carb source.
WhenFrom race start. Fat-adapted athletes may tolerate beginning slightly lower and increasing as the race progresses.
Dose60-80g carbs/hr as the current community standard. Bitter's pre-low-carb approach was 400-500 cal/hr almost entirely from carbs.
For whomSingle-day ultra runners. Multi-day events require different strategies as gut tolerance changes and overall caloric replacement becomes the primary constraint.
WhyEven in fat-adapted athletes, sustained race pace generates some glycolytic demand. Exogenous carbohydrate spares whatever muscle and liver glycogen was stored before the race. For 24+ hour events a small protein component (part of the 15-25%) helps attenuate muscle catabolism.
CaveatsGut tolerance for 60-80g/hr has to be built up in training long runs, not first tested on race day.
The evolution from Bitter's high-carb years (400-500 cal/hr all-carb) to the current position statement reflects both field experience and emerging research. The 2:1 glucose:fructose ratio product formulations now common in sports nutrition can increase gut carbohydrate absorption from ~60g/hr to potentially 90g/hr by using separate intestinal transporters. Bitter notes the field is still evolving — the recommendation that was 50-70g/hr a few years ago is now 60-80g/hr and continuing to drift upward.
The ultr running position statement right now would suggest around you know it start out at 50 to 70 grams I think it's starting to skew up actually closer to 60 to 80 grams of carbohydrate and then what they usually say for like a single day Ultra you should probably have 75 to 85% of that be carbohydrate and then 15 to 25% of that be some blend of fats and proteins
VO2 max speedwork development phase (8-12 weeks) before race-specific zone 2 peaking
WhatRun a dedicated speed development block 8-12 weeks out from the target race. Short intervals: 2-4 min at VO2 max pace, 1:1 work-to-rest ratio. Long intervals: 8-12 min at lactate threshold pace, 2:1 work-to-rest ratio. After this block, transition to race-specific zone 2 volume.
WhenEarly in the training plan, at least 8-10 weeks before race day.
Dose8-12 week speedwork development phase. Short intervals: 5-6 reps of 2-4 min (1:1 work:rest). Long intervals: 3-5 reps of 8-12 min (2:1 work:rest).
For whomUltra runners who have plateaued on zone 2 training. Particularly valuable for time-crunched athletes (10hr/week or less) who cannot simply add more volume.
WhyRaising the VO2 max ceiling means the same zone 2 pace becomes a lower percentage of max effort. After the speed phase, athletes do the same 10 hours/week of easy running but at a faster pace at the same RPE — a free performance upgrade without added training load.
CaveatsThis phase is least specific to ultra racing — no point in a 100-miler touches VO2 max. The benefit is systemic metabolic elevation, not movement-pattern specificity.
Bitter's analogy: it's like sharpening the saw. If someone is training 10 hours/week all at the same low intensity and has plateaued, adding more of the same won't help but replacing 15-20% of that volume with higher-intensity intervals for one block creates a new metabolic baseline. He uses this approach with coached athletes whose occupational NEAT already provides extensive zone 1-2 stimulus — for those athletes, higher-intensity work is the missing variable.
I'll do like a speedwork development phase where we do kind of short intervals pinned to their V2 Max long intervals pinned to their lactate threshold and kind of pull that whole system up so then if we decide like let's say we do an 8 to 12 week speedwork development phase now we go back to them running those easy 10 hours per week they're doing it faster but at the same intensity so that run feels the same as it did prior but they're doing it quicker
Sweat-test electrolyte calibration: weigh in/out + known sodium concentration
WhatWeigh yourself immediately before and after a 1-hour run in conditions representative of your target event. Weight differential in kg equals approximate liters of fluid lost. Multiply by your personal sweat sodium concentration (Bitter's: 614mg/L) to get actual sodium lost. Configure electrolyte replacement to match.
WhenCalibrate once per climate zone and season. Repeat if body composition or training load changes substantially.
DoseOne test run for initial calibration. Spread electrolyte replacement throughout the run rather than front-loading.
For whomAny endurance athlete training or racing in heat. Critical for events over 3 hours where cumulative sodium deficit can impair performance or cause hyponatremia.
WhyIndividual sweat rates and sweat sodium concentrations vary enormously between athletes. Population-average recommendations will over- or under-replace for most individuals.
CaveatsSweat sodium concentration ideally comes from a formal sweat test. The 614mg/L figure is Bitter's personal measurement and is not a universal default.
In hot conditions (Austin/Houston), the math matters: if Bitter sweats 1.5L/hr for a 4-hour long run, that is 6L of fluid and approximately 3,686mg sodium — far above what most sports drinks provide at standard concentrations. Bitter describes using Element electrolytes (sodium, potassium, magnesium) during his 11:52 100-mile run in June as part of this calibrated approach.
I know that I lose 614 milligrams of electrolytes for every liter of sweat so if I go and I do a run for 1 hour in the summer and I weigh myself before and after and figure out about how many liters of fluid I'm going to lose I can kind of pair that with the electrolyte sodium and make sure I'm staying on top of that
Embed visualization into long training runs (negative-split mental rehearsal)
WhatDuring 3-4 hour long runs, choose a race segment to mentally rehearse while running physically. In the final 30-45 minutes of the run, execute a slight pace progression (negative split) while simultaneously visualizing the corresponding late-race segment at accelerating pace.
WhenEvery long run in the peaking phase, 8-12 weeks out from the target event.
Dose30-45 min of embedded visualization per long run session. Negative-split progression: 10-15 sec/mile faster per segment in the final 30 min.
For whomAny athlete competing in events long enough to produce cognitive fatigue (generally 3+ hours).
WhyRacing at mile 70-80 of a 100-miler requires cognitive responses under conditions of profound fatigue. Rehearsing those responses while actually fatigued in training creates memory-encoded automatic responses rather than deliberate calculation in the race.
Bitter's framing: the mental and physical battery are linked. An athlete who is physically ready but has to actively deliberate every decision under fatigue drains the mental battery prematurely. By rehearsing specific scenarios repeatedly in training, those scenarios shift from deliberate to automatic — more working memory freed for novel problems on race day. The 2015-2019 gap in his 100-mile world record attempt is the data point: in world-record shape in 2015, missed by 11.5 minutes due to pacing and late-race cognitive failure; by 2019, the same late-race surge was a scripted response.
When I ran my fastest 100 mile when I was doing these long runs I would do like a slight progression at the end and that entire long run block I was basically visualizing like the end of the race where I was telling myself like as I get further I can go faster and you're just trying to like convince yourself that like both physically and mentally that that's possible so you're running on fatigued legs I can still push harder
Exogenous ketones: take 45-60 min into low-intensity long efforts, not pre-run
WhatFor long, low-intensity efforts (zone 2 and below), introduce exogenous ketones 45-60 minutes into the run, not before. Avoid for sessions targeting VO2 max or lactate threshold intensity.
WhenDuring long slow runs (2+ hours), race simulations, or multi-hour track sessions where cognitive fatigue becomes a limiting factor.
DoseStandard product serving at 45-60 min mark. Bitter uses them daily for this specific timing.
For whomEndurance athletes doing 3+ hour sessions who experience cognitive fatigue as a limiting factor. Particularly relevant for multi-day events.
WhyTaking exogenous ketones pre-run creates a sluggish warm-up. Waiting 45-60 min allows normal warm-up while still providing cognitive support for the bulk of the session. High-intensity sessions may be impaired (research suggests interference with glycolytic output).
CaveatsExogenous ketones are expensive and the performance-enhancement evidence is mixed. The use case here is specifically cognitive fatigue management, not energy provision.
The cognitive application: Bitter trains on 400-meter tracks for race-specific preparation. Four hours on a 400-meter loop generates significant cognitive fatigue from monotony. Exogenous ketones allow mental engagement with visualization practices rather than defaulting to passive endurance of boredom. Lyon mentions she also cannot perform quick, explosive efforts after taking exogenous ketones, which aligns with Bitter's caution about high-intensity sessions.
I started introducing it like maybe 45 60 Minutes in and that seemed to be a lot better of a strategy for me so if I'm doing something in the easier intensity category I'll have exogenous ketones during it and some of that I think the research is like suggestive at least that it's going to be helpful with the cognitive side of things so when cognitive fatigue or the ability to kind of like focus versus have your mind be like fluttering in all sorts of different directions
Blood-test-first supplement strategy: identify deficiencies before supplementing
WhatRun a comprehensive blood panel before committing to any supplement stack. Identify actual deficiencies and target supplements specifically. Use tracking apps (Cronometer, Carbon) to see where dietary inputs are falling short first.
WhenAt least annually. Also whenever dietary patterns shift substantially.
DoseAnnual blood panel. Supplement for identified gaps only.
For whomAny endurance athlete, especially those on restrictive diets (very low carb, strict animal-based, or vegan) where specific micronutrient gaps are predictable.
WhyRandom supplementation wastes money and can create imbalances. Blood testing reveals actual status rather than relying on generic population recommendations.
CaveatsSerum levels do not always reflect tissue stores for magnesium, iron, and vitamin D. Functional testing adds nuance.
Bitter's personal stack: magnesium (from blood work), creatine (currently testing 5g/day), caffeine, exogenous ketones, multivitamin when traveling. His creatine empiricism — started 10g, got GI distress day 4, pulled to 5g — is the same approach he recommends for all supplementation: trial with a monitored baseline, not protocol-copying.
Rather than like throwing all their money at all the supplements get a blood test and see where they can optimize on always so like when I get blood tests like things they'll show up or like I could maybe improve this so then usually I'll add a supplement around that so like magnesium is what I'm doing right now
Prioritize strength in offseason: heavy compound lifts to build durability
WhatUse the offseason to build a strength foundation with heavy compound lifts in a 3-10 rep range. Include some single-leg balance and coordination work. Reduce strength volume when running volume ramps toward peak.
WhenOffseason and early base-building phase.
Dose30-60 minutes, 2-3x per week during offseason.
For whomAll endurance runners, particularly those with recurring tendinopathy or stress injuries. More urgent for athletes over 40.
WhyStrength work in the offseason makes athletes more injury-resistant throughout the training cycle. Reduced injury frequency compounds as consistency — the primary driver of long-term improvement.
CaveatsIf limited to 30 min/week, prioritize compound lifts over isolation work. Goal is neural-mechanical durability, not hypertrophy.
Most runners are going to benefit from doing heavier weight stuff because a lot of times we're just doing more of the same and I think like if you if someone really wants to do some strength training that's going to really move the needle for me and running for performance I've got like you know 30 minutes per week then we're going to do the heavier compound lifts in probably like even a three to maybe up to 10 rep range
What's new
Personal practice updates, fresh positions, predictions
8 items
Low-carb ultra record: 12+ years of periodized low-carb fueling at world-record pace
~45 min
Bitter has maintained a low-carbohydrate diet since 2011 while setting and breaking multiple American and world ultra records. His approach is not fixed-macro; it oscillates between strict ketogenic phases (<50g carbs) in offseason and up to 300g carbs on hard speedwork days. The through-line is always matching the fuel to the metabolic demand of the session.
Why this matters: The dominant narrative in endurance nutrition is that carbohydrate is obligatory at high volumes. Bitter ran 100 miles at 6:47/mile pace as a world record on a diet that would conventionally be considered incompatible with elite performance.
Background
Before switching in 2011, Bitter was consuming 600g+ carbs per day training 70-100 miles per week — standard high-carbohydrate endurance fueling. The switch was motivated by energy roller-coaster effects and sleep disruption, not performance failure.
The FASTER study (Fat-Adapted Substrate oxidation in Trained Elite Runners), which Bitter participated in, took 10 low-carb-ketogenic ultra athletes and 10 high-carb athletes through identical testing. Both groups arrived at similar glycogen stores post-exercise; the high-carb group had started with more and burned more, while the low-carb group started with less and burned less. Bitter's critique: the similar relative dip does not mean he could simply stay ketogenic indefinitely for all phases — he observes a real performance ceiling in VO2 max intervals when carbs are chronically too low.
I was part of the faster study so tell me about that what's up yeah so it was a study where they took 10 ultramarathon athletes that were low carb ketogenic and 10 that were high carb and they sort of ran them through the same testing protocol to just tease out like what was going on differently and what they noticed with that was that when they tested the low carb ketogenic diet athletes they just we all kind of arrived at the same glycogen stores at the end of the training sessions it was just the high carb were burning through a lot more of it when they were doing the workout and the low carb was burning through way less of it so the relative dip was pretty similar
Also said
“I went like pretty strict ketogenic for about a month during my offseason and I actually felt pretty good pretty soon — I started sleeping through the night, some of that might have been because I was facing it offseason too but it sort of continued into when I started training specifically again”— First-person account of the transition: the initial low-carb benefit was improved sleep quality and energy stability, not raw performance.
Carbohydrate periodization by training day — not by week or phase alone
~55 min
Bitter evolved beyond simple 'low carb' into intra-week carb cycling: strict keto on rest and easy days (under 50g), escalating to 200-300g on hard interval days. He describes discarding the idea that nutrition resets every 24 hours and thinking in terms of the full week's training stimulus.
Why this matters: Most endurance nutrition advice operates at the level of 'daily macros' or 'phase macros'. Bitter's approach is more granular — each day's carbohydrate is sized to that day's glycolytic demand, which allows very low average carb intake while still supporting high-quality intervals.
Background
The insight came when he noticed that on strict keto he could do a single VO2 max session fine but could not stack high-quality interval sessions week after week — track splits were 3-4 seconds slower per lap at the same perceived effort.
The practical model: if Tuesday and Thursday are short-interval sessions at VO2 max, those days get up to 300g carbs (including sports gels and drinks taken before and during the sessions). Monday, Wednesday, and Friday might be near-zero-carb. The weekly average stays low while peak-day carb availability supports the glycolytic bursts. This is structurally similar to targeted-ketogenic diet (TKD) protocols used in strength sports but applied to ultra-endurance training cycles.
I sort of like just got rid of the idea of like this thing resets every 24 hours and started thinking of it as like how do I maximize the fuel source for the work I'm doing so if I had like an easy run or a rest day I might stick to that stricter ketogenic protocol and have very little to no carbohydrates on a day like that so that would be 50 or less yep and then I might be doing short intervals on Tuesday and Thursday so I might have sometimes two I've had days where I've close to 300 gram of carbohydrates on days like that
The FASTER study: similar glycogen depletion profiles across metabolic strategies
~58 min
Bitter's participation in the FASTER study showed that low-carb-ketogenic ultra runners and high-carb ultra runners arrived at similar post-exercise glycogen levels — the high-carb group started and burned more, the low-carb group started and burned less. The relative metabolic stress was comparable.
Why this matters: This is direct empirical evidence addressing the 'you can't perform without glycogen' objection. Both strategies converge on similar depletion endpoints, which means the question is really about what happens at the performance ceiling rather than base function.
It was a study where they took 10 ultramarathon athletes that were low carb ketogenic and 10 that were high carb and they sort of ran them through the same testing protocol and what they noticed with that was that we all kind of arrived at the same glycogen stores at the end of the training sessions it was just the high carb were burning through a lot more of it when they were doing the workout and the low carb was burning through way less of it so the relative dip was pretty similar
Visualization practice embedded in long runs — not as separate mental training
~1 h 35 min
During 3-4 hour training runs, Bitter actively visualizes specific race-day scenarios: hitting the hard spot at mile 70 and pushing through, running the last miles faster than the first. By the time he reaches those moments in the actual race, the response is habituated rather than effortful.
Why this matters: Most mental skills training is compartmentalized — done in meditation sessions or pre-race visualization. Bitter integrates it into physical sessions, pairing the fatigue state of a long run with the mental rehearsal, which more accurately replicates the race condition.
Background
The key breakthrough was the 2019 100-mile world record attempt. His 2015 attempt had him in world-record shape but paced too aggressively, missing by 11.5 minutes. Between 2015 and 2019 he worked specifically on the late-race segment and built visualization of the positive outcome into training runs.
His tactical version: when doing a 3-4 hour long run, he would visualize running at 7:00/mile average and then in the final miles progressively cutting to 6:55 and then 6:00 — a closing negative split. In training he'd actually do this progression at the end of the long run. On race day the closing acceleration felt like a scripted event rather than an act of will. He ran his fastest miles in the final segment of his world-record run.
One thing that worked really well for me was when I ran my fastest 100 mile when I was doing these long runs I would do like a slight progression at the end where I would cut the pace down a little bit and that entire long run block I was basically visualizing like the end of the race where I was telling myself like as I get further I can go faster and you're just trying to like convince yourself that like both physically and mentally that that's possible so you're running on fatigued legs I can still push harder
Exogenous ketones as cognitive fuel during long low-intensity efforts — not for speed
~1 h 42 min
Bitter uses exogenous ketones during long easy efforts for cognitive maintenance, taking them 45-60 minutes into a run rather than pre-run. He avoids them before high-intensity sessions — emerging research suggests they may impair short high-intensity efforts (e.g., 5K PRs).
Why this matters: The exogenous ketone literature has been muddied by the use of them in contexts where they are likely to be counterproductive. The timing and intensity-matching principle provides a framework that reconciles the pro-cognitive evidence with the performance-impairment evidence.
Background
Bitter originally took exogenous ketones before long runs and found a prolonged warm-up effect — the body felt sluggish getting up to speed. Shifting to 45-60 min into the run resolved this.
The application for multi-day or >24-hour events: when out on a 400-meter track for 3-4 hours doing long runs as race simulation, exogenous ketones help divert attention from the mechanical lap-count and support the visualization work. For cognitive fatigue in late-race ultra settings, the sustained ketone availability likely reduces the CNS cost of sustained effort. Bitter views this as an emerging area — possibly a meaningful addition to the sleep-deprivation management toolkit for multi-day events as research matures.
I started introducing it like maybe 45 60 Minutes in and that seemed to be a lot better of a strategy for me so if I'm doing something in the easier intensity category I'll have exogenous ketones during it and some of that for some I think the research is like suggestive at least that it's going to be helpful with the cognitive side of things so when cognitive fatigue or the ability to kind of like focus versus have your mind be like fluttering in all sorts of different directions
Build-in VO2 max speedwork early in training, taper to race-specific zone 2 late
~1 h 15 min
Bitter's periodization model runs least-specific to most-specific: a VO2 max speedwork development phase (8-12 weeks of short intervals at 12-min effort, long intervals at lactate threshold) followed by a race-specific zone 2 peaking phase. Doing VO2 max work early raises the metabolic ceiling so that the same zone 2 pace becomes easier — athletes can run faster at the same RPE.
Why this matters: Many ultra runners train only at race-specific slow paces. Bitter argues that a VO2 max phase that is 'least specific' to ultra racing is still necessary to raise the floor of what zone 2 can deliver.
I'll do like a speedwork development phase where we do kind of short intervals pinned to their V2 Max long intervals pinned to their lactate threshold and kind of pull that whole system up so then if we decide like let's say we do an 8 to 12 week speedwork development phase now we go back to them running those easy 10 hours per week they're doing it faster but at the same intensity so that run feels the same as it did prior but they're doing it quicker
Sweat-test-calibrated electrolyte strategy — personal measurement, not package labels
~1 h 40 min
Bitter measures his own sweat rate by weighing himself before and after an outdoor run and combining that with a known sweat sodium concentration of 614mg per liter of sweat. This lets him calculate actual electrolyte replacement needs for any given run duration and ambient conditions.
Why this matters: Standard electrolyte product dosing is population-average and does not account for individual sweat rate variation (which can differ by 5-10x between athletes). Personal calibration is the only way to get this right for high-stakes events.
I know that I lose 614 milligrams of electrolytes for every liter of sweat so if I go and I do a run for 1 hour in the summer and I weigh myself before and after and figure out about how many liters of fluid I'm going to lose I can kind of pair that with the electrolyte sodium and make sure I'm staying on top of that
Caffeine ceiling in multi-day events — creatine as cognitive gap-filler
~1 h 42 min
Bitter uses 200mg caffeine daily and will go up to 400-600mg on race day, but recognizes caffeine cannot be dosed continuously across a 24-hour event. He is actively exploring creatine as a supplement that may help navigate sleep deprivation without the ceiling problem of caffeine.
Why this matters: The sleep-deprivation literature on creatine is newer (post-2020) and potentially transformative for ultra events. Bitter explicitly connects this to the gap that caffeine cannot fill in events exceeding 20-24 hours.
Caffeine has a ceiling to it so I can't be hitting caffeine every hour for 24 hours necessarily eventually I've got to not do that and if there's something else like creatine where I can sort of fill the gaps with that and also get some advantage from that then I think that's an interesting input there
Recommendations
Products, supplements, and tools mentioned in the episode
2 items
Creatine monohydrate (5g/day) for recovery and sleep-deprivation tolerance
Supplement
Bitter is actively testing creatine at 5g/day and is interested specifically in the recent research on creatine and sleep deprivation — potentially a key tool for multi-day events where caffeine cannot be continuously dosed.
Recent research (2020+) shows creatine supplementation partially compensates for cognitive and physical performance decrements after sleep restriction. For ultra events where athletes lose one or more nights of sleep (100-milers take 11-30+ hours), this could be a meaningful intervention. Bitter cites Brady Homer and Darren Candow's work on the extended creatine literature beyond muscle performance.
vs alternatives
Caffeine is the standard cognitive performance supplement for ultra racing but has a ceiling dose and creates dependency/tolerance with continuous use. Creatine's sleep-deprivation data suggests a complementary mechanism — cognitive support via phosphocreatine resynthesis rather than adenosine antagonism.
Personal experience
Currently trialing 5g/day, building up empirically after GI intolerance at 10g/day.
Creatine's probably the most proven in research and I've done creatine and I've come off of it in the past just to kind of see and right now I'm trying it again — I started at 10 gram and I just pulled back to five because 10 seemed like a little too much I got to day four and then I had a digestive issue
Exogenous ketones for long low-intensity efforts and multi-day events
Supplement
Bitter uses exogenous ketones almost daily, primarily during long easy runs and as a cognitive support tool. He takes them ~45-60 min into a session, not pre-run.
He cautions against using them for high-intensity sessions (possible glycolytic interference). The specific use case he finds compelling: running for 3-4 hours on a 400-meter track doing race simulation — exogenous ketones allow mental engagement rather than passive monotony endurance.
vs alternatives
Caffeine provides stimulation but with a ceiling and dependency risk. Carbohydrate feeding maintains glycolytic output but does not specifically address cognitive fatigue mechanisms. Ketones appear to support CNS function via an alternate substrate pathway.
Personal experience
Uses almost every day; timing shift from pre-run to 45-60 min in resolved sluggish warm-up effect.
I started introducing it like maybe 45 60 Minutes in and that seemed to be a lot better of a strategy for me so if I'm doing something in the easier intensity category I'll have exogenous ketones during it
Carbon app for macro tracking and carb periodization calibration
Tool Sponsored · disclosed
Bitter recommends tracking dietary inputs against a chosen macro framework using apps, specifically naming Carbon and Cronometer as tools he uses with coaching clients.
DisclosureBitter and Lyon mention Carbon by name and reference providing a listener discount code.
We actually use Carbon — that's get it through and see where you're at and we'll give you guys a code for it they're amazing
Electrolyte supplementation calibrated to personal sweat testing (Element featured)
Supplement Sponsored · disclosed
Electrolyte replacement keyed to personal sweat sodium loss. Strategy: weigh before and after a representative run, use known sodium concentration (~614mg/L of sweat for Bitter) to calculate replacement needs.
DisclosureElement (LMNT) is an episode sponsor. Bitter used Element Sparkling during his 11:52 100-mile run in June.
vs alternatives
Plain water without electrolytes risks dilutional hyponatremia in events over 4-6 hours. Generic sports drink formulations may under- or over-replace based on individual sweat rate variation.
I know that I lose 614 milligrams of electrolytes for every liter of sweat so if I go and I do a run for 1 hour in the summer and I weigh myself before and after and figure out about how many liters of fluid I'm going to lose I can kind of pair that with the electrolyte sodium and make sure I'm staying on top of that
Lines worth pulling out — contrarian, specific, or perfectly phrased
6 items
I sort of like just got rid of the idea of like this thing resets every 24 hours and started thinking of it as like how do I maximize the fuel source for the work I'm doing.
The conceptual foundation of Bitter's carb periodization — a clean reframe that unlocks day-by-day flexibility within a low-carb lifestyle.
I don't mean there aren't trade-offs — there are trade-offs. I just think the trade-offs are smaller than the benefits for me at the race intensity I'm doing.
Honest acknowledgment that low-carb ultra performance is not free — the trade-off in VO2 max peak output is real, just less consequential at 100-mile intensity than at 5K intensity.
Your physical battery and your mental battery — if you're in the best shape of your life but you're constantly overthinking things or fixating on something that went wrong or aiming for perfection when that's probably not technically on the table, you're just going to drain yourself mentally and then when it comes to the end of the race when you really need to call on that, it's not there anymore.
Core practical argument for building automatic mental responses in training — cognitive energy is finite and must be conserved for late-race decisions.
I think the biggest question they should be asking themselves is which diet am I able to pretty easily stick to where I don't feel like I'm forcing this, I enjoy it, I don't get like weird hunger pangs, I'm sleeping and recovering well with it — all those things that go into just making sure you can continue to do it for as long as I have.
The pragmatic north star for nutrition selection — dietary sustainability as the primary criterion, above any ideological or macronutrient purity argument.
Caffeine has a ceiling to it so I can't be hitting caffeine every hour for 24 hours necessarily, eventually I've got to not do that — and if there's something else like creatine where I can sort of fill the gaps with that and also get some advantage from that, then I think that's an interesting input.
Frames the multi-day event supplement problem: caffeine works but saturates; creatine's emerging sleep-deprivation data is a potential game-changer for events exceeding 24 hours.
For every good race I've had I've had multiples that went backwards where I dropped out or just finished at a really really slow pace relative to what I started out at — crashing and burning is a way to kind of figure out well that was too aggressive.
Elite-level reframe of race failure as calibration data, not moral failure — useful for athletes who avoid taking risks because they fear a DNF.
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