Insulin before or after training

Why Bodybuilders Use Insulin (for context)

Advanced competitive bodybuilders sometimes combine insulin with growth hormone (GH) or anabolic steroids to:

Increase glycogen storage in muscles (makes them fuller)

Enhance amino acid and glucose uptakePromote recovery and growth

However, this practice is not medically approved, illegal in many federations, and carries serious health risks — especially without a doctor monitoring blood glucose levels and nutrition precisely.

 

The Physiology (How Insulin Works for Muscle Growth)

Insulin:

Drives amino acids and glucose into muscle cells

Increases glycogen storageReduces muscle breakdown (anti-catabolic effect)

These effects can support growth — but only when glucose levels are managed perfectly.

Timing

Physiological Effect

Muscle Growth Potential

Risk Level

Before Training

Increases nutrient uptake before exercise, but can drop blood sugar rapidly once you start lifting

Some benefit in theory (better pump, glycogen use), but highly risky — exercise increases insulin sensitivity further

🚨 Very High Risk (hypoglycemia mid-workout)

After Training

Insulin helps drive carbs and amino acids into depleted muscle cells — supports glycogen and recovery

✅ Best timing for muscle growth — if medically supervised and paired with immediate carbs + protein

âš ï¸ Moderate–High risk if unsupervised

✅ In Summary

Post-training insulin activity (natural or injected under medical care) is the most anabolic and safest window.

The post-workout insulin spike — natural or assisted — enhances:
Glycogen resynthesisProtein synthesisNutrient absorption
 

So, after training is the preferred and physiologically optimal time for insulin’s muscle-building effects — but only safely if you’re managing it medically (e.g., a diabetic athlete under endocrinologist supervision).