Carbohydrate Timing: What It Does, Which Is Less Than the Supplement Aisle Implies

Q: Does carb timing matter for muscle growth?

Far less than total daily carbohydrate and total daily energy. Timing becomes meaningful when you train more than once a day, when sessions are long and glycogen-depleting, or when you are competing and need to arrive at a specific session with full stores. For one training session a day in a fed state, hitting your daily total is nearly all of it.

Q: Should I eat carbs before or after training?

Either works for a single daily session. Before is more useful if the session is long or you train fasted and find performance suffers; after is more useful if you train again within about eight hours and need to restore glycogen quickly. If neither describes you, put the carbohydrate where you enjoy eating it.

Q: Do I need carbs immediately after training?

Only if you are training again soon. The 'anabolic window' framing was built on studies of fasted training and rapid re-training, and for someone who ate before the gym and will not train again for a day, glycogen restoration has many hours to occur. The window is measured in hours, not minutes.

Carbohydrate timing is a real variable with a small effect for most people, and a large effect for a small number of people. Sorting out which you are is the whole exercise.

When timing genuinely matters

Training twice in a day. Glycogen has to be restored between sessions, and there the clock is real.

Long, glycogen-depleting sessions. Endurance work, or very high-volume lifting sessions past about ninety minutes.

Competition. Arriving at a specific session with full stores is a legitimate reason to manipulate timing precisely.

When it does not

Glycogen restoration, one session a day

Muscle glycogen depleted by a hard lifting session: ~30–40%

Time until the next session: ~24 hours

Time needed to restore, given adequate daily carbohydrate: < 24 hours

There is no shortage of time. The window framing came from studies where subjects trained fasted and again soon after, which describes very few people reading this.

What the “anabolic window” was

An inference from studies of fasted training with rapid re-training, generalised to everybody and then sold protein powder against.

If you ate a meal containing protein two hours before training, that meal is still being absorbed during the session. The urgency the marketing implies has no corresponding physiology.

The practical version

Hit your daily carbohydrate total. Put it where it makes your training feel good and your day easy to eat.

If you train hard and your sessions feel flat, eating more carbohydrate before them is a reasonable experiment — and worth running for two weeks before drawing a conclusion, because session-to-session variation is large enough to fool you over three days.

The measurement note

Carbohydrate is the macro most affected by portion estimation, because it comes largely from foods that are poured or scooped rather than weighed — rice, oats, pasta, cereal. If your carb total is wrong, it is usually wrong here, and it is usually low.

Weighing dry grains for a week is the cheapest correction available.

Questions we get asked

Does carb timing matter for muscle growth?

Far less than total daily carbohydrate and total daily energy. Timing becomes meaningful when you train more than once a day, when sessions are long and glycogen-depleting, or when you are competing and need to arrive at a specific session with full stores. For one training session a day in a fed state, hitting your daily total is nearly all of it.

Should I eat carbs before or after training?

Either works for a single daily session. Before is more useful if the session is long or you train fasted and find performance suffers; after is more useful if you train again within about eight hours and need to restore glycogen quickly. If neither describes you, put the carbohydrate where you enjoy eating it.

Do I need carbs immediately after training?

Only if you are training again soon. The 'anabolic window' framing was built on studies of fasted training and rapid re-training, and for someone who ate before the gym and will not train again for a day, glycogen restoration has many hours to occur. The window is measured in hours, not minutes.

Tessa Lindqvist

Contributing writer, nutrition · Stronger by Math

Writes about intake, adherence and what the self-monitoring literature actually supports. Weighs her own food, which is why she is sceptical of estimates — including the good ones.