Intermittent Fasting: The Complete Beginner's Guide
Intermittent fasting (IF) is one of the most studied and most effective natural approaches to weight loss. It doesn't prescribe what you eat — it prescribes when you eat. Thousands of studies support it for fat loss, metabolic health, and longevity. Here's everything you need to start.
The main IF protocols
Fast 16 hours, eat within an 8-hour window. Example: eat noon–8pm, fast 8pm–noon. The most sustainable protocol — you sleep through most of the fast. Best starting point for beginners.
Fast 18 hours, eat within 6 hours. Step up from 16:8. Example: eat 1pm–7pm. More pronounced metabolic benefits, slightly more challenging to maintain socially.
Eat normally 5 days, restrict to 500–600 calories 2 non-consecutive days per week. Good for people who prefer flexibility over daily restrictions.
Eat all your calories in one sitting. Aggressive — not recommended as a starting point. Works well for some people once adapted to fasting, but hard to hit protein targets.
What breaks a fast?
Does NOT break a fast:
- Black coffee (no milk, no sugar)
- Plain tea
- Water, sparkling water
- Electrolytes (no sugar — see below)
- Most medications
DOES break a fast:
- Any calories — milk in coffee, bulletproof coffee, cream
- Protein powder, BCAAs (triggers insulin response)
- Sugar in any form
- Chewing gum with calories
Supplements that help during fasting
Common beginner mistakes
- Not eating enough protein during the eating window — IF doesn't change your protein needs. Hit 0.7–1g per lb bodyweight in your eating window.
- Breaking the fast with refined carbs — your first meal matters. Protein-first breaks fasts better than toast or cereal.
- Exercising in a long fast without electrolytes — performance tanks without sodium. LMNT during fasted workouts makes a real difference.
- Going too aggressive too fast — start with 14:10, build to 16:8 over 2 weeks. Jumping straight to OMAD is a recipe for quitting.
- Expecting linear results — water weight fluctuates. Judge by weekly averages, not daily weigh-ins.
Expected results
Most people lose 0.5–1.5 lbs per week on 16:8 combined with reasonable eating. After 3 months, expect 6–18 lbs depending on consistency and what you eat. Results accelerate with strength training. IF works best as a long-term lifestyle, not a crash diet.
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