Fueling FAQ

What does Training Fuel Sync calculate?

It starts with maintenance outside planned training, adds the net cost of each workout, then applies your weight goal. Protein and fat stay steady while carbohydrate rises and falls with the work. Completed workout data replaces the plan when it becomes available.

What does “fuel for the work required” mean here?

Carbohydrate availability follows the duration and intensity of the session instead of a flat daily diet. Harder and longer work receives more carbohydrate. A demanding session tomorrow can also raise today’s target so glycogen is available before the session begins.

The approach is based on the Fuel for the Work Required framework. Training Fuel Sync turns that framework into a planning heuristic; it is not an individualized sports-dietitian prescription.

How do the weight-loss approaches differ?

Every choice is capped at 500 kcal/day (configurable), halved on days with a Key session, and suspended around races. Rest days carry the deficit and the more work a day holds, the more of its fuel it keeps; the deficit never turns into a surplus and never underfuels the work. The dashboard shows the projected 7-day outcome rather than promising a rate, since scale weight also moves with water and glycogen. None of the choices will ever prescribe a larger deficit than the gentler one.

Forgot to mark a session beforehand? Open the completed workout on the dashboard and apply Key workout or Competition there; the dashboard recalculates the day immediately. Competition is the option that suspends the race-day deficit.

Can a loss strategy underfuel a hard workout?

The requested deficit is only the first pass. Training Fuel Sync then protects the carbohydrate assigned to the workload plus configured protein and a fat floor; fat drops toward its floor before calories rise. If the floors still need more energy, the app reduces or removes that day’s deficit, and an optional energy-availability guard (needs a body fat %) sets a lower bound per kg of lean mass. Race-loading days can suspend the deficit entirely.

Are tomorrow’s workouts prioritized?

Only workouts you mark as Key workout in the editor. The day before a Key session raises the carbohydrate floor (default 4 g/kg) with calories held at or below maintenance — it is never a surplus day. Zones, hard-looking titles, and power targets do not qualify on their own; sessions under 90 minutes are fuelled by normal daily eating plus 1–4 g/kg in the hours before. Competition carb loading is separate.

Why did carb loading change?

The old rule gave every competition three days at 8 g/kg — for weekly short races that put much of the week on loading calories. The evidence supports full loading (10–12 g/kg for 36–48 h) only for events over about 90 minutes; shorter events need daily fuel plus a pre-race meal. Loading now scales with race length: races up to 90 minutes get one day at 6 g/kg, longer races get two days at 10 g/kg, and race day itself uses the normal session-based floor. Races without a duration count as 60 minutes (short) until you add one on the dashboard. In each competition’s editor, Carb load (days) can override the default window for that event; leave it blank to use these settings, enter 0–3 days, or use 0 to skip the extra pre-race load.

What does the fuel guide use?

The guide card is display-only — it never changes the goal. During-session targets follow the published duration and intensity bands (nothing under ~45–75 minutes, 30–60 g/h for 1–2.5 h, up to 90 g/h beyond, +5 g/h for key sessions and races). Before-session advice gives 1–4 g/kg in the 1–4 h before for longer, harder, key, or race sessions; after-session advice depends on how soon the next session is. Carbohydrate eaten during sessions counts toward the day’s target; it is not extra.

Why can two loss approaches show the same calories?

The carbohydrate floor, your “never go below” setting, or the calorie maximum can override the requested adjustment, and the 500 kcal cap binds aggressive days on big training. The dashboard shows the requested weight-goal adjustment and any fuel-floor correction separately so you can see when a guardrail won.

Why might Training Fuel Sync differ from Hexis?

Hexis does not publish its complete calculation, so Training Fuel Sync exposes its own inputs instead: maintenance, estimated or completed workout energy, the named loss approach, fixed protein with a fat floor, and workload-based carbohydrate. Measured against the same athlete and plan, Hexis “Maintain” ends every day within ±15 kcal of zero; its “Lose 10 %” takes roughly 9–10 % of each day’s expenditure (this app’s balanced approach takes about as much over a typical week, but puts more of it on rest days), displaces ~90 kcal/h during sessions, and pre-fuels a Key flag only slightly the day before — while its Competition flag adds about a day at 6.4 g/kg before a 90-minute race. Where the two disagree it is usually maintenance assumptions, workout energy, or pre-fuelling strength.

Does Training Fuel Sync diagnose low energy availability or RED-S?

No. It knows fat-free mass only if you enter a body fat estimate, and it knows nothing of health history or clinical symptoms. The carbohydrate floor and calorie limits are planning safeguards. Persistent fatigue, declining performance, menstrual disruption, recurrent injury, or other concerns need an appropriately qualified clinician or sports dietitian.

When does the automatic sync run?

The hosted app's scheduler re-syncs every connected account about every 15 minutes, around the clock, and the ↻ Sync data button on the dashboard runs one immediately. Unchanged goals are never rewritten to MyFitnessPal.

Which training platform should I connect?

intervals.icu is the recommended connection: one setup covers the plan, completed workouts, weight, body fat, and FTP, and it is the only platform that can notify Training Fuel Sync the moment something changes, so a finished workout or calendar edit shows up within seconds. TrainingPeaks works fully as the plan source, but it has no notification channel for third-party apps — TrainingPeaks-sourced data refreshes on the regular ~15-minute cycle, and the browser cookie that connects it must be re-pasted when it expires.