Diet Program Guide
Intermittent Fasting 16:8
Fast for 16 hours, eat within an 8-hour window — no restrictions on what you eat
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Intermittent fasting (IF) is an eating pattern that cycles between periods of fasting and eating. Unlike most diet programs, it doesn't prescribe what you eat — it prescribes when you eat. The 16:8 method is the most widely practiced form: you fast for 16 consecutive hours and consume all your food within an 8-hour window each day.
The most common 16:8 schedule skips breakfast, breaking the fast around noon and finishing eating by 8pm. The fasting window includes sleep, making it less demanding than it sounds. During the fasting window, only zero-calorie drinks — water, black coffee and plain tea — are consumed.
The primary mechanism for weight loss is straightforward: a shorter eating window tends to reduce total daily calorie intake naturally, without requiring food restriction or calorie counting. Additional research suggests that fasting periods may improve insulin sensitivity and metabolic flexibility, though long-term clinical evidence remains mixed.
How the 16:8 Window Works
FAST — 16 hours (e.g. 8pm → 12pm)
EAT — 8 hours (12pm → 8pm)
Fasting window: water, black coffee, plain tea only
Eating window: all meals and snacks within 8 hours
Key Principles
- Choose a consistent 8-hour eating window and stick to it daily
- During the fast: only water, black coffee and plain (unsweetened) tea
- No specific food restrictions within the eating window — quality matters, but nothing is banned
- Don't compensate for the fast by overeating — IF works because total intake naturally decreases
- Prioritise protein and vegetables within the eating window for best body composition results
- Consistency is more important than the exact timing — shift the window if needed
- Combine with a generally healthy diet for best results
What to Eat & What to Avoid
✓ During eating window
- Any whole, nutrient-dense foods
- Lean proteins — chicken, fish, eggs
- Vegetables and salads
- Whole grains — oats, rice, quinoa
- Legumes — lentils, beans
- Healthy fats — avocado, olive oil, nuts
- Fruit and dairy (if tolerated)
✗ During fasting window
- Any food (breaks the fast)
- Milk, cream or sugar in coffee/tea
- Fruit juice, soft drinks or alcohol
- BCAA supplements or protein powder
- Chewing gum with sugar
- Anything with meaningful calories
A Typical 16:8 Day (12pm–8pm eating window)
8am – 12pm
Fasting window — water, black coffee or plain tea only
12pm (Break fast)
Grilled chicken with a large salad, avocado and olive oil dressing — first meal of the day~540 kcal · 45g protein · 26g fat · 28g carbs
4pm (Snack)
Greek yogurt with berries and a handful of almonds~280 kcal · 18g protein · 14g fat · 22g carbs
7:30pm (Dinner)
Salmon with roasted vegetables and brown rice. Last meal before the fast begins~560 kcal · 42g protein · 20g fat · 48g carbs
8pm – 12pm
Fasting window begins — water only until tomorrow noon
Who It Suits Best
IF 16:8 works well for people who are not hungry in the morning and naturally skip or delay breakfast, those who want structure without food restriction, busy people who prefer fewer daily meals, and those who have struggled to maintain calorie deficits through traditional dieting.
It's less suitable for people who experience blood sugar drops or dizziness when delaying eating, those with a history of disordered eating, pregnant or breastfeeding women, people with diabetes who take medication affecting blood sugar timing, and individuals who exercise intensely in the morning before noon.
Advantages & Disadvantages
Advantages
- Simple — no food tracking or rules about what to eat
- Naturally reduces calorie intake
- Compatible with any dietary preference
- May improve insulin sensitivity
- Simplifies meal planning (fewer meals)
- Many find it easier to sustain long-term
Disadvantages
- Morning hunger in the first 1–2 weeks
- Social breakfast challenges
- No food restriction means quality must be self-managed
- Not appropriate for everyone (see above)
- Some research suggests different effects in women
- Doesn't address food quality directly
Tips & Tricks
- Start with a 12:12 window and work up. If 16 hours feels too long at first, begin with 12 hours of fasting and gradually extend by 30 minutes every few days until you reach 16.
- Black coffee is your best tool. Coffee suppresses appetite significantly and contains essentially zero calories. Most people find the 16-hour fast much easier with a morning coffee. Espresso, Americano and filter coffee are all fine.
- Drink a large glass of water immediately on waking. Hunger in the morning is often partly thirst. 500ml of water at 7am makes it much easier to push through to noon.
- Keep your first meal protein-rich. Breaking the fast with a high-protein meal — eggs, chicken, Greek yogurt — reduces hunger for the rest of the eating window and protects muscle mass.
- Plan your window around your social life. There's nothing magic about 12pm–8pm. If you prefer 10am–6pm or 2pm–10pm to fit your schedule or social eating, adjust accordingly.
- Expect 2 weeks of adjustment. Hunger is largely hormonal and habit-driven. Most people find the fasting window feels natural and comfortable within 10–14 days.
Frequently Asked Questions
What breaks the fast?
Any intake with meaningful calories breaks the fast. This includes milk in coffee, fruit juice, protein shakes, BCAA supplements and food. Black coffee, plain tea and water do not break the fast and can be consumed freely during the fasting window. Some debate exists around very small amounts (under 50 kcal), but for simplicity, stick to zero-calorie drinks only.
Will I lose muscle on 16:8?
Not significantly, provided you eat sufficient protein within your eating window (1.6g+ per kg of body weight) and maintain resistance training. The 16-hour fast is not long enough to cause meaningful muscle breakdown in healthy individuals. Short-term fasting actually increases growth hormone, which helps preserve muscle. Longer fasting periods (24+ hours) pose more risk to muscle mass.
Is intermittent fasting safe for women?
Most women can follow 16:8 safely. However, some research suggests that women may be more sensitive to calorie restriction and fasting than men, with potential effects on menstrual cycles and hormonal balance if fasting is too aggressive. Starting with a less strict window (14:10) and monitoring how you feel is a sensible approach. Women who are pregnant, breastfeeding or trying to conceive should avoid fasting without medical guidance.
Can I exercise during the fasting window?
Yes. Many people exercise fasted without issue, particularly for moderate-intensity cardio and strength training. Some people find fasted training beneficial for fat oxidation. Others experience reduced performance. If you train intensely in the morning, you may prefer to schedule your eating window to include your post-workout period, ensuring you can eat protein within an hour of training.
How much weight will I lose with 16:8?
Weight loss depends on whether IF creates a calorie deficit for you. If you eat the same total calories in 8 hours as you did in 16, you won't lose weight. Most people naturally eat fewer calories in a restricted window, which produces gradual weight loss. Combining 16:8 with a generally healthy diet typically produces 0.5–1kg of fat loss per week.
Free Tools to Support Intermittent Fasting
Disclaimer: This guide is for general educational purposes only. Intermittent fasting is not appropriate for everyone. Consult your GP or a registered dietitian before starting, particularly if you have diabetes, take medication affecting blood sugar, have a history of disordered eating, or are pregnant or breastfeeding.
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