Longevity Ninjas

Simple Intermittent Fasting Protocol

Fasting Protocol · 8 min read

Intermittent fasting (IF) is one of the most accessible and well-studied longevity interventions. The 16:8 protocol — 16 hours fasting, 8 hours eating — is the sweet spot for most people: effective enough to trigger autophagy and metabolic benefits, sustainable enough to maintain for years.

Key Takeaways

  • The 16:8 protocol (eat within an 8-hour window) is the most sustainable and well-researched IF approach.
  • Water, black coffee, and plain tea do NOT break a fast.
  • Protein intake must remain high (1.2-1.6g/kg) — just compressed into fewer meals.
  • Eating earlier in the day (e.g., 8am-4pm) aligns with circadian biology for maximum benefit.
  • Women may benefit from a gentler approach: 14:10 or cycling IF 3-5 days per week.

The 16:8 Framework

The simplest version: stop eating after dinner, skip breakfast, and eat your first meal at lunch. Here’s the structure:

  • Eating window: 8 hours (e.g., 12pm-8pm, 10am-6pm, or 8am-4pm)
  • Fasting window: 16 hours (includes sleep — you’re fasting for ~8 waking hours)
  • Number of meals: 2-3 meals within your eating window
  • Earlier windows (8am-4pm or 10am-6pm) are metabolically superior — insulin sensitivity is highest in the morning
  • The late window (12pm-8pm) is more socially convenient but slightly less optimal metabolically
  • Choose the window you can sustain — consistency matters more than timing perfection

What Breaks a Fast (And What Doesn’t)

The most common question in IF. Here’s the definitive breakdown:

  • Does NOT break a fast: Water, sparkling water, black coffee, plain green/black/herbal tea, salt, electrolytes (zero-calorie)
  • Does NOT break a fast: Apple cider vinegar (1 tbsp in water), lemon/lime juice (small squeeze)
  • BREAKS a fast: Any food, protein shakes, bone broth, milk/cream in coffee, BCAAs, gummy vitamins
  • Gray area: MCT oil, butter coffee — these provide calories but may not spike insulin. They break a ‘clean fast’ but may preserve some autophagy benefits
  • For maximum autophagy and metabolic benefits, keep it clean: water, black coffee, plain tea only

Week 1-2: Adaptation Phase

Your body needs 1-2 weeks to adapt to a compressed eating window. Expect some hunger — it passes:

  • Start with a 14:10 window if 16:8 feels too aggressive (e.g., 9am-7pm)
  • Push your eating window later by 30 minutes every 2-3 days until you reach your target
  • Hunger comes in waves — it peaks and passes within 20-30 minutes. Drink water or black coffee
  • Salt in water during the morning fast prevents energy dips from electrolyte loss
  • Don’t try to reduce calories simultaneously — focus on timing first
  • By day 10-14, morning hunger typically disappears as ghrelin (hunger hormone) resets

Optimizing Your Eating Window

What you eat during your window matters enormously. IF isn’t a license to eat junk in 8 hours:

  • Meal 1 (break-fast): High protein (30-40g), moderate fat, low-moderate carbs. Example: eggs + avocado + vegetables
  • Meal 2 (main): Largest meal. Protein (40-50g) + complex carbs + vegetables. Example: salmon + sweet potato + salad
  • Meal 3 (optional): Light meal or snack if needed. Greek yogurt with berries, or a protein shake
  • Total daily protein: 1.2-1.6g per kg — this doesn’t change with IF, it just gets compressed into fewer meals
  • Eat protein FIRST, then vegetables, then carbs — this order reduces glucose spikes by up to 40%
  • Don’t compensate for fasting by overeating — let hunger guide portions, not deprivation anxiety

Training While Fasting

Exercise and fasting can work together, but timing and fueling require attention:

  • Fasted cardio (zone 2): Safe and potentially enhances fat oxidation. Stay hydrated with electrolytes
  • Fasted strength training: Works for some, but performance may suffer. Experiment individually
  • Ideal: Train near the end of your fast, then break your fast with protein within 1 hour of finishing
  • If training hard while fasted, caffeine (black coffee) 30 minutes before can boost performance
  • Post-workout: Prioritize 30-40g protein + carbs to maximize recovery and muscle protein synthesis
  • If performance drops significantly, consider shifting your eating window to include pre-workout nutrition

Special Considerations for Women

Women’s hormonal systems are more sensitive to fasting stress. A modified approach often works better:

  • Start with 14:10 rather than 16:8 — many women thrive on a gentler window
  • Cycle IF: Fast 3-5 days per week rather than daily — this prevents hormonal disruption
  • Avoid fasting during the luteal phase (week before period) — progesterone is high and the body needs more fuel
  • Monitor menstrual regularity — if cycles become irregular, reduce fasting frequency or shorten the window
  • If experiencing hair loss, fatigue, or sleep disruption, IF may be too aggressive — pull back
  • Pregnant and breastfeeding women should not practice intermittent fasting

The Bottom Line

Start with a 14:10 window and progress to 16:8 over 2 weeks. Keep protein high (1.2-1.6g/kg), eat earlier when possible, stay hydrated with electrolytes, and prioritize consistency over perfection.

Educational content, not medical advice. Talk with your doctor before starting any protocol — full medical disclaimer.