Triathlon training nutrition: fuelling three sports in one week
A triathlete’s daily carbohydrate should follow the day’s training, not the week’s average. The ACSM, AND and Dietitians of Canada guidance gives 3-5 g/kg on light days, 5-7 g/kg for about an hour of training, and 6-10 g/kg for 1-3 hour days. Sessions over an hour add 30-90 g of carbs per hour.
Three sports make a triathlete’s week the most uneven in endurance sport. A 45-minute technique swim and a four-hour brick can sit two days apart. A flat calorie target is wrong on both of them. You need to read each day’s fuel cost from the sessions on it.
How many carbs does a triathlete need per day?
It ranges from 3 to 10 g per kg of bodyweight, scaled to the day’s training. The ACSM, AND and Dietitians of Canada joint position on nutrition and athletic performance (Thomas, Erdman and Burke, 2016) sets these daily ranges:
| Training that day | Carbs, g per kg per day |
|---|---|
| Light: low intensity or skill-based | 3-5 |
| Moderate: about 1 hour a day | 5-7 |
| High: 1-3 hours, moderate to high intensity | 6-10 |
| Very high: more than 4-5 hours | 8-12 |
This is the idea behind fuel for the work required (Impey et al., 2018). Carbohydrate is adjusted to the demands of the upcoming session instead of held constant.
How much should you eat during a long ride or run?
Aim for 30-60 g of carbs per hour in sessions of 1-2.5 hours, and up to 90 g per hour beyond about 2.5-3 hours. Those figures are also from the joint position. It notes that the higher rates rely on mixes of glucose and fructose, and that intake needs practice to suit your gut. Sessions under 45 minutes don’t need fuel during them.
The bike is where most of that fuelling happens. On the bike you can eat and drink easily. You can’t in the pool, and it’s harder at run pace. If a long brick is on the plan, fuel the ride for the run that follows.
What does a triathlon training week look like on a plate?
Take a 70 kg age-grouper on about 11 hours a week. Each day is matched to the joint-position band that fits its load:
| Day | Training | Band | Daily carbs |
|---|---|---|---|
| Mon | Rest or 45-min technique swim | Light, 3-5 g/kg | 210-350 g |
| Tue | 1-h run intervals | Moderate, 5-7 g/kg | 350-490 g |
| Wed | 1-h swim + 1-h tempo ride | High, 6-10 g/kg | 420-700 g |
| Thu | 1-h tempo run | Moderate, 5-7 g/kg | 350-490 g |
| Fri | 1-h swim | Moderate, 5-7 g/kg | 350-490 g |
| Sat | 3-h ride + 30-min brick run | High, 6-10 g/kg | 420-700 g |
| Sun | 1.5-h long run | High, 6-10 g/kg | 420-700 g |
Saturday’s ride also calls for fuel during the session. Three hours at 60-90 g an hour is 180-270 g of carbs, and that counts toward the day’s total.
Sunday’s 90-minute run needs 30-60 g an hour if you fuel during it, which is 45-90 g. Monday drops back to the light band, where the upper limit is half of Saturday’s.
Protein doesn’t swing like this. The ISSN position stand gives 1.4-2.0 g/kg/day for people who exercise, spread over meals every 3-4 hours. Keep it steady across the week and let carbohydrate do the moving.
These bands are wide on purpose. Where you land inside one depends on intensity, body size and whether you are also trying to lose weight. Treat the numbers as a starting frame, not a prescription.
How do you handle double-session days?
Refuel between the sessions. If the gap is short, the joint position suggests 1-1.2 g/kg of carbs per hour for the first four hours after the first session. For 70 kg that is 70-84 g an hour.
That applies when two fuel-demanding sessions sit less than eight hours apart. A morning swim followed by an evening ride with a full day of meals between them needs no special plan, only normal meals.
What changes in race week?
Training volume drops and carbs go up. For events longer than about 90 minutes, the joint position describes 36-48 hours of 10-12 g/kg before the race. For 70 kg that is 700-840 g a day.
A sprint triathlon doesn’t need that. A 70.3 or full distance usually does. The build-up is covered in how to fuel a race without guessing.
How Sweatmeal handles this
Sweatmeal reads your sessions from Strava, Apple Health or Health Connect, Whoop, Oura or Ultrahuman. It sizes each day’s calorie and carb target to that day’s load, so the brick day and the swim-technique day get different numbers. Training days keep a carb floor, and a race on your calendar lifts it for race week. Garmin isn’t supported yet. See the methodology page for how it’s calculated.