Your race, fueled leg by leg.
Carbs, fluid and sodium for each leg — capped at the rate you have actually trained your gut to take, not a number off a chart.
Your training plan's other half.
You'll follow a 20-week plan down to the session. Fuelog writes the nutrition side of it — periodized carbohydrate, a race-day plan leg by leg, and a gut-training ramp to make that plan achievable.
Periodized carbohydrate
3 to 12 g/kg, decided daily
A rest day and a six-hour ride are not the same nutrition problem, and no single multiplier can express a four-fold range. Fuelog sets carbohydrate from your actual training load, then scales the curve by where you are in the season.
Carbohydrate is reserved first, before protein and fat, because for an endurance athlete it is the macro the day is built around. When the calorie budget cannot hold all three, Fuelog reports the shortfall instead of quietly shaving carbs.
Race day
Carbs per hour, leg by leg
The same athlete has a different gut on the bike than on the run. So Fuelog prescribes nothing in the water, runs the bike slightly above your target rate, and drops the run about 25% below it — then caps the whole plan at the rate you have actually trained.
Illustrative 70.3 split for an athlete whose plan comes out at 86 g/h. Your own rate, fluid and sodium come from your weight, your goal time, your sweat test and your trained tolerance.
No sign-up, no email gate. Same engine as the app.
Gut training ramp
90 g/h is a trained number, not a starting point. Fuelog builds the ramp at about +10 g/h every two and a half weeks — 60 to 90 g/h is roughly eight weeks of practice, 60 to 110 is about thirteen. If the race is too close to close the gap, the plan says so and caps you at the rate you can actually reach.
Energy availability
Intake minus training energy, divided by fat-free mass. Fuelog's coach works this out from your logged food, your Apple Health workouts and your body-composition entry before it answers you, so a question about a heavy week comes back with an answer that knows what you have left to train on. Most trackers show calories in and calories out and stop there.
The carb-load window
Loading only makes sense for races long enough to deplete glycogen, so Fuelog prescribes a load for events over 90 minutes — 10.5 g/kg, rising to 11.5 g/kg once the race runs past four hours. Shorter than that and it stays off.
Fluid and sodium from your own test
Enter a weigh-in sweat test and Fuelog works from your number instead of the 0.9 L/h population default. It replaces 70% of losses rather than 100%, adds 25% for a hot race day, and turns your sweat sodium into milligrams per leg.
Mixed carbs above 60 g/h
Glucose transport saturates near 60 g/h. Any time your prescribed rate goes above it, Fuelog flags that you need a glucose:fructose blend around 1:0.8 — a single-source gel physically cannot absorb fast enough past that ceiling.
Sprint through full distance
Sprint, Olympic, 70.3 and Ironman course splits are built in. Give it a goal finish time and it estimates your swim, bike and run durations, then fuels each one separately instead of averaging the whole day into one number.
Educational tool, not medical or dietary advice. Never try a new fueling plan for the first time on race day.
Your race, right now.
Pick the distance, a goal time and the carb rate you have practised. The plan below comes off the same engine as the app — no account, no email gate.
| Leg | Time | Carbs | Total | Fluid | Sodium |
|---|---|---|---|---|---|
| Swim | 0h 36m | — | — | — | — |
| Bike | 3h 12m | 63 g/h | 200 g | 2 L / 68 oz | 2003 mg |
| Run | 2h 12m | 45 g/h | 100 g | 1.4 L / 47 oz | 1399 mg |
- Capped at your trained 60 g/h rather than the 105 g/h this duration supports. Gut training closes that gap.
- Your bike rate is above 60 g/h, so you need mixed glucose:fructose (1:0.8). A single-source product will not absorb fast enough and will sit in your gut.
- Using the 0.9 L/h population default. Do a sweat-rate test — individual rates vary more than any other variable here.
- Practise this exact plan on at least two long sessions before race day.
Your gut is the limit, not the guideline
105 g/h needs roughly 13 weeks and you have 10. Race at 100 g/h — a rate you have actually trained beats one you have only read about.
Carb loading
11.5 g/kg — about 861 g of carbohydrate a day for the 36–48 h before the start.
Caffeine
225–449 mg across the race (3–6 mg/kg). Only if you already use it in training.
Use a mixed-carb product
Above 60 g/h you need glucose:fructose at 1:0.8. Glucose transport saturates around that rate, and fructose crosses on a separate transporter — a single-source drink or gel physically cannot absorb fast enough.
This is one race. Fuelog is the whole build.
The same engine runs inside the app, where it uses your real training load from Apple Health — whatever watch or strap writes there — and moves this plan every time your trained tolerance goes up. Leave your email and this plan, with your numbers, comes with the launch note.
Educational tool, not medical or dietary advice. Every number here is a starting point to practise in training — never try a new fueling plan for the first time on race day. If you have a medical condition affecting nutrition or hydration, talk to a qualified professional.
Fuel the session. Then fuel the race.
Race day is one plan. Fuelog spends the other twenty weeks making sure the daily carbs, the logging and the gut training get you there.
Daily carbs that follow your training
A rest day and a six-hour ride get different numbers. Your targets are set from the session you actually did, so the day after a long ride reads like one.
Logging that does not take ten minutes
Point the camera at the plate and Fuelog identifies it, estimates portions and logs the macros. Barcode and Siri cover the rest.
Targets that move with the day
Carbohydrate is set from your logged training load and the phase of your season, then the rest of the plate is built around it.
Barcode scanner
Scan any packaged food — gels and drink mix included — for nutrition data pulled from a large product database.
Recipe builder
Build your race-week meals once and log them in a single tap, with macros calculated per serving.
Siri Shortcuts
"Hey Siri, what are my carbs today?" Get the number without opening the app mid-ride.
A coach that has read your week
The coach works from your logged food, your Apple Health workouts and your body-composition entry, so a question about a heavy week gets an answer that knows what you have left.
Weekly insight
One breakdown a week: where the carbs landed against the plan, what to change before the next long session.
From meal to insight in four steps
No spreadsheets, no manual calorie math. Fuelog connects the dots for you.
Enter the race and your trained rate
Distance, goal time, weight and the carb rate you have practised. Fuelog splits the day into legs and puts a number on each.
Connect Apple Health
Every workout your watch or strap writes to HealthKit becomes training load — no manual entry.
Get carbs that follow the load
Daily carbohydrate is set from the session you did and the phase of your season, then the plate is built around it.
Log in seconds
Photo, barcode or Siri. The plan only works if logging it is faster than skipping it.
Your training, read from Apple Health
Fuelog reads the session you actually did through Apple Health and sets the next day's carbohydrate from it — one connection, no manual entry. Garmin, Strava and TrainingPeaks are not connected yet; anything they write to HealthKit still counts.
Apple Health
One connection. Every workout, heart-rate and sleep sample any device writes to HealthKit.
Whoop
HRV, resting heart rate and sleep from your strap give the coach the context for a hard week.
Apple Watch
The ride you record on your wrist is the training load that sets tomorrow's carbs.
Oura
Sleep your ring writes to HealthKit, read the same way — no second login.
Stop guessing
your race-day numbers.
Fuelog is launching on the App Store. Leave your email to be first in line — early testers get free TestFlight access through their A-race.
Launching on iPhone · One email at launch · No spam, ever