Delaying carbs after exercise doesn't improve the body's adaptive response—but it does make your next workout feel harder and shorter.

Why Glycogen Matters

Glycogen is how your body stores carbohydrates in muscles and the liver. After a tough workout—especially one involving high-intensity intervals—your glycogen stores are depleted. Refilling those stores is critical for:

  • Energy for your next session

  • Supporting performance

  • Maintaining training consistency

What the Study Looked At

This 2024 study explored whether delaying carbohydrate intake by 3 hours after high-intensity interval exercise (HIIE) would:

  • Improve molecular signals that drive long-term training adaptations (e.g., mitochondrial biogenesis)

  • Affect muscle glycogen resynthesis

  • Influence next-day exercise capacity

The Setup

Nine recreationally active males completed two trials:

  • Immediate Carbs (IC): Consumed 2.4g/kg of carbohydrate immediately post-exercise.

  • Delayed Carbs (DC): Waited 3 hours before consuming the same carbs.

Both groups consumed a standardized high-carb diet for the rest of the day. Researchers measured:

  • Muscle glycogen at 0, 3, 8, and 24 hours

  • Key gene and protein activity

  • Performance in a repeat HIIE test 24 hours later

What They Found

Muscle Glycogen Resynthesis

  • Glycogen levels were depleted ~36% post-HIIE in both groups.

  • Glycogen refilled progressively and fully recovered by 24 hours in both groups.

  • No significant differences in glycogen levels at any time point.

  • Suggests that as long as you get enough carbs later, delaying intake for a few hours won’t hurt glycogen restoration.

Next-Day Performance

  • Athletes who delayed carbs performed ~30% worse in a repeat HIIE session the next day.

  • They also reported significantly higher perceived effort (RPE) during that workout.

Cell Signaling & Adaptation

  • No significant differences in gene expression (PGC-1α, PDK4, etc.) or protein signaling (p38 MAPK, AMPK) between groups.

  • Delaying carbs did not enhance exercise-induced molecular responses.

What This Means for You

If you train once per day:

  • Delaying carbs by a couple of hours won’t harm glycogen replenishment, as long as total daily intake is sufficient.

  • But don’t expect any boost in adaptation or fitness gains from waiting.

If you train multiple times/day or again within 24 hours:

  • Refuel ASAP. Delaying carbs will likely reduce performance in your next session and make it feel harder.

  • This matters for:

    • Competitive athletes

    • High-volume functional fitness athletes, endurance athletes, or lifting programs

    • Weekend warriors doing two-a-days

Practical Tips

  • Within 30 minutes post-exercise: Aim for 1.0–1.2g/kg of high-GI carbs + some protein (e.g., chocolate milk, rice + eggs, smoothie).

  • Total daily carbs: Can vary from 2g/kg up to 10g/kg depending on training volume, intensity for form of exercise (resistance training vs long-endurance training as an example).

  • Don’t delay carbs if performance tomorrow matters.

Bottom Line:
Unless you're testing advanced periodization strategies, don't delay post-workout carbs. The potential gains in adaptation are unclear—but the loss in next-day performance is very real.

References


Díaz-Lara J, Reisman E, Botella J, Probert B, Burke LM, Bishop DJ, Lee MJ. Delaying post-exercise carbohydrate intake impairs next-day exercise capacity but not muscle glycogen or molecular responses. Acta Physiol (Oxf). 2024 Oct;240(10):e14215. doi: 10.1111/apha.14215. Epub 2024 Sep 12. PMID: 39263899.

Comment