16/8 Intermittent Fasting: Complete Guide for Trainees
Intermittent fasting (IF) is not a diet — it is an eating window. 16 hours of fasting, 8 hours of eating. Nothing mystical, just a structured approach that suits many trainees better than the traditional "eat every 3 hours" advice.
This guide gives you a concrete plan for starting the 16/8 protocol, training around it, and choosing the right supplements.
Who This Guide Is For
Trainees who want to try 16/8 intermittent fasting for fat loss, better focus, or simpler meal planning. After reading, you will know how to plan your day, training, and supplements.
TL;DR: 16/8 Essentials
- Fasting window: 16 hours (including sleep)
- Eating window: 8 hours (e.g., 12:00-20:00)
- Calories are not counted differently — fat loss still comes from caloric deficit
- Caffeine and water are allowed during fasting
- Creatine and fat-free supplements can be taken during fasting
- This is not magic — it is a tool that works better for some people
How Does 16/8 Work?
Intermittent fasting is not a miracle cure. Its main mechanism for fat loss is simple: a shorter eating window usually means fewer calories. Research (Moro et al., 2016) shows that 16/8 IF in trainees produced:
- Greater fat mass reduction than the control group (same calories)
- Equivalent muscle mass preservation
- Improved insulin sensitivity
- Reduced inflammation markers
However: if you eat the same calories in 8 hours as you previously did in 16 hours, you will not lose weight.
Planning Your Eating Window
Option A: Late Breakfast (Most Popular)
- Fast: 20:00 - 12:00 (16h)
- Eating window: 12:00 - 20:00 (8h)
- Suits: Office workers, evening trainers
Option B: Early Breakfast
- Fast: 16:00 - 08:00 (16h)
- Eating window: 08:00 - 16:00 (8h)
- Suits: Morning trainers, early riser lifestyle
Option C: Nordic Winter Variant
- Fast: 19:00 - 11:00 (16h)
- Eating window: 11:00 - 19:00 (8h)
- Suits: Northern European winters, when days are short and energy needs are high
Pro tip: Start with a 14/10 split (14h fast, 10h eating window) for the first 1-2 weeks, then move to 16/8.
Training on the 16/8 Protocol
Fasted Training
Training in a fasted state is possible but needs adjustment:
- Intensity: Low-to-moderate intensity works well during fasting
- Strength training: Possible, but performance may drop 5-10%
- BCAA/EAA before training: 5-10g EAA before fasted training protects muscle mass without significantly "breaking" the fast
Training During the Eating Window (Recommended)
Ideally, train during the first half of your eating window:
1. 11:30 — Caffeine (on empty stomach, during fast)
2. 12:00 — Light pre-workout meal (30-40g protein + carbs)
3. 13:30-15:00 — Training
4. 15:30 — Largest meal (40-50g protein, carbs, fats)
5. 19:30 — Last meal
Protein Intake — Important Warning
The biggest risk with 16/8 is protein deficit. With an 8-hour window, you need to fit your entire daily protein (1.6-2.2g/kg) into 2-3 meals. This requires conscious planning.
Example for 80kg male (160g protein):
- Meal 1 (12:00): 50g protein (e.g., 200g chicken breast + 2 eggs)
- Meal 2 (16:00): 50g protein (e.g., protein powder 2 scoops + nuts)
- Meal 3 (19:30): 60g protein (e.g., 250g salmon + quark)
Supplements for Intermittent Fasting
Allowed During Fasting (will not break the fast):
- Caffeine/coffee — black coffee, no milk or sugar
- Creatine monohydrate — 0 calories, does not affect fasting
- Electrolytes — sodium, potassium, magnesium
- Vitamin D — capsules without fat will not break the fast (but absorbs better with fat)
During the Eating Window:
- Protein powder — critically important for sufficient protein
- Omega-3 — fat-soluble, take with food
- Multivitamins — fat-soluble vitamins need food
- ZMA/zinc — evening before bed
Before Fasted Training:
- 5-10g EAA or BCAA — protects muscles, minimal calories (~20-40 kcal)
- 200mg caffeine — stimulating effect without calories
- 5g creatine — does not break the fast
Sample Weekly Plan
Training Day (Mon, Wed, Fri)
- 07:00 Black coffee + creatine 5g
- 12:00 First meal: 50g protein + carbs
- 14:00-15:30 Strength training
- 16:00 Post-workout meal: 50g protein + carbs
- 19:30 Last meal: 40g protein + fats + vegetables
- 20:00 Fasting begins
Rest Day (Tue, Thu, Sat, Sun)
- 07:00 Black coffee
- 12:00 First meal: 40g protein + healthy fats
- 16:00 Second meal: 40g protein + vegetables
- 19:30 Last meal: 40g protein + fats
- 20:00 Fasting begins
Common Mistakes
1. Too little protein — in 8 hours, you need 2-3 high-protein meals. Use protein powder as supplemental protein
2. Too large a first meal — do not eat the entire day's calories at once. This causes lethargy
3. Overdoing caffeine during fasting — 4-5 coffees on an empty stomach wrecks digestion
4. Ignoring training quality — if performance drops significantly, try eating before training
5. Excessive focus on window length — 14/10 is better than 16/8 that makes you miserable. Consistency matters most
16/8 in the Estonian Context
Intermittent fasting is growing in popularity among Estonian trainees. Some specific aspects relevant to Estonia:
- Winter darkness — short days make an early eating window difficult. Option C (11:00-19:00) fits winter better
- Food culture — the traditional Estonian warm lunch fits well with a 12:00-20:00 window
- Quark and kefir — excellent protein sources for a compact eating window. 250g quark provides ~30g protein
- Sauna training — hydration after sauna is especially important. Electrolytes during fasting help
Peak gym hours in Estonian gyms are 17:00-20:00, meaning most trainees work out in the second half of their eating window. This is fine — plan your largest meal post-workout.
Local Food Options for the Eating Window:
- First meal (12:00): Oatmeal with protein powder, berries, nuts
- Post-workout (17:00): Chicken breast, rice, vegetables
- Last meal (19:30): Quark, nut butter, fruit
Who Should NOT Do 16/8?
- Pregnant and breastfeeding women — nutrient needs are too high
- People with eating disorders — a strict eating window can worsen the disorder
- Underweight individuals — caloric restriction is contraindicated
- Type 1 diabetics — blood sugar control requires regular meals
- Under 18 — growing body requirements
Can you build muscle on 16/8?
Yes, but it is harder. Building muscle requires a caloric surplus, which is harder to achieve in 8 hours. Moro et al. (2016) showed that muscle mass was preserved on 16/8, but for growth you need to consciously eat more.
Tip: use a mass gainer or add more carbs during the eating window.
Does 16/8 speed up fat loss compared to a regular diet?
Not directly. Studies (Cioffi et al., 2018) show that with the same calories, fat loss is similar regardless of the eating window. The advantage of 16/8 is simplicity: fewer meals to plan, clear structure.
Is coffee during fasting allowed?
Yes, black coffee (no milk, sugar, or cream) does not break the fast. Caffeine even raises metabolic rate by 3-11% (Dulloo et al., 1989). But do not drink more than 2-3 cups on an empty stomach.
How long should you maintain the 16/8 schedule?
It is more a lifestyle than a program. Many people use it indefinitely. You can always be flexible: 14/10 on weekends, 16/8 on weekdays. The key is sustainability.
What supplements are most important during intermittent fasting?
Electrolytes (sodium, potassium, magnesium) during fasting and protein powder during the eating window to ensure sufficient protein. These two cover the essentials.
References
1. Moro T, Tinsley G, Bianco A, et al. (2016). Effects of eight weeks of time-restricted feeding (16/8) on basal metabolism, maximal strength, body composition, inflammation, and cardiovascular risk factors in resistance-trained males. Journal of Translational Medicine, 14(1), 290.
2. de Cabo R, Mattson MP. (2019). Effects of intermittent fasting on health, aging, and disease. New England Journal of Medicine, 381(26), 2541-2551.
3. Tinsley GM, La Bounty PM. (2015). Effects of intermittent fasting on body composition and clinical health markers in humans. Nutrition Reviews, 73(10), 661-674.
4. Patterson RE, Sears DD. (2017). Metabolic effects of intermittent fasting. Annual Review of Nutrition, 37, 371-393.
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