Insulin Aspart (NovoLog)
Insulin aspart (NovoLog / NovoRapid) is a rapid-acting insulin analogue with a single B28 proline-to-aspartate substitution. Clinically it covers mealtime glucose; in bodybuilding it is used interchangeably with lispro for post-workout nutrient partitioning. It carries the same rapid, potentially fatal hypoglycaemia risk.
01 Overview
The aspartic-acid substitution at B28 reduces hexamer formation, so aspart absorbs and acts faster than regular insulin, closely matching lispro. It is a widely prescribed, well-characterised drug for type 1 and type 2 diabetes.
Physique users dose it around carbohydrate-rich meals or training to enhance glycogen loading and anabolic signalling. As with all fast analogues, small overdoses or inadequate carbohydrate produce rapid neuroglycopenia; deaths in non-diabetic users are well documented.
02 Mechanism
Activates the insulin receptor to promote GLUT4-mediated glucose uptake, glycogen and protein synthesis and suppression of lipolysis and gluconeogenesis. The monomeric-favouring substitution gives rapid onset (~10-20 min) and short duration.
03 Dosing
| Tier | Dose | Route | Notes |
|---|---|---|---|
| Beginner (off-label) | 1–5 IU | SubQ | With generous carbohydrate; extreme caution |
| Diabetic bolus | 4–20 IU | SubQ | Individualised; medical use only |
| Common (off-label) | 5–10 IU | SubQ | Risk rises steeply with units |
04 Effects
| Effect | Magnitude | Evidence | |
|---|---|---|---|
| Glycogen supercompensationRapidly shuttles glucose into muscle when paired with carbohydrate. | Increased muscle glycogen and fullness | Clinical | |
| Anabolic / anti-catabolic actionStimulates protein synthesis and blunts breakdown via insulin-receptor signalling. | Clinical |
05 Side effects
| Effect | Severity | Frequency | Evidence | Countermeasures |
|---|---|---|---|---|
| Weight/fat gainAdipose gain when calories exceed needs. | Mild | Common | Clinical | |
| Severe hypoglycaemiaRapid glucose crash with tremor, confusion, seizure, coma and possible death. | Life-threatening | Common in misuse | Clinical |