Alternate Day Fasting (ADF) — Diets
Cyclic fasting protocol alternating between ad libitum feeding days and very low calorie or zero-calorie fasting days.
Overview
Alternate Day Fasting (ADF) involves alternating between feast days (ad libitum intake) and fast days (0-25% of energy needs, typically 500 kcal). ADF is one of the most rigorously studied intermittent fasting approaches with multiple RCTs demonstrating significant weight loss (3-8% over 8-12 weeks), improvements in LDL cholesterol, triglycerides, and insulin resistance. The HELENA trial showed ADF produced comparable metabolic benefits to continuous CR with potentially better adherence in some populations. Modified ADF (allowing 500 kcal on fast days) shows similar benefits with improved compliance.
Indications
- Weight and fat loss
- Dyslipidemia improvement
- Insulin resistance reduction
- Cardiovascular risk factor management
Mechanism of Action
Alternating feast/fast days creates a net caloric deficit without daily restriction
Dosing
| Compound | Dose | Frequency | Notes |
|---|---|---|---|
| Alternate Day Fasting (Modified) | 500 kcal on fast days | Every other day | Modified ADF; better adherence than complete fasting |
| Alternate Day Fasting (Complete) | 0 kcal on fast days | Every other day | Complete fasting; greater autophagy but lower adherence |
Safety & Contraindications
- Hunger, irritability, and difficulty concentrating on fast days
- Risk of compensatory overeating on feast days
- Not recommended for type 1 diabetes, eating disorders, or pregnancy
- May reduce exercise performance on fast days
- Potential for lean mass loss without adequate protein intake