Fasting Guide: Time-Restricted
Eating & Extended Fasts

1. Introduction — Why Low-Carb Leads Naturally to Fasting

If you've been eating low-carb for a while, you might have noticed something strange: you're just not that hungry in the morning anymore. This isn't a fluke. When you reduce carbohydrates, your insulin levels stabilise and your hunger hormones — specifically ghrelin — stop screaming for attention every three hours.

For many of us, intermittent fasting wasn't something we "decided" to do; it was something that happened accidentally. We'd push breakfast back until 10am, then noon, and suddenly we were fasting for 16 hours a day without even trying.

This guide covers everything from those first steps into time-restricted eating to the deeper metabolic territory of multi-day fasts, all written with a UK lifestyle in mind.

2. What is Intermittent Fasting?

Intermittent fasting (IF) isn't a diet in the traditional sense. It doesn't tell you what to eat, but rather when to eat. It is simply a pattern of cycling between periods of eating and periods of fasting.

While it feels like a modern trend, fasting is ancient. Historically, humans didn't have 24-hour supermarkets or refrigerators stocked with snacks. Our ancestors naturally cycled through periods of feast and famine. Today, we are mostly in a state of perpetual "feast," which can lead to metabolic issues. Fasting allows our bodies to tap into stored energy (body fat) for a change.

• Time-Restricted Eating (TRE): Daily patterns like 16:8 where you eat within a specific window.
• Extended Fasting: Fasts lasting 24 hours or longer, typically used for deeper metabolic resets.

3. Time-Restricted Eating (TRE) Protocols

These are the most popular ways to incorporate fasting into daily life. They are sustainable and work brilliantly alongside a low-carb diet.

a) 12:12 — The Entry Point

This involves a 12-hour eating window and a 12-hour fast. For example, you finish dinner by 8pm and don't eat again until 8am. Who it suits: Complete beginners. It's essentially what people used to do before "midnight snacking" became common.

b) 16:8 — The Most Popular Protocol

16 hours of fasting and an 8-hour eating window (e.g. noon to 8pm). Most people achieve this by skipping breakfast and having their first meal at lunch. Practical UK Tip: If you're used to a "Full English" or cereal at 7am, try pushing it back by one hour every few days. Once you reach noon, you're doing 16:8.

c) 18:6 — Stepping It Up

An 18-hour fast with a 6-hour eating window. This often naturally happens when you find two substantial meals a day are enough to keep you full.

d) 20:4 — The Warrior Diet

A 4-hour eating window, usually late in the afternoon or evening. You might have one very large meal and perhaps a smaller snack a few hours later.

e) OMAD — One Meal A Day

Exactly what it says: you eat all your daily calories in a single, nutritionally dense meal. It saves an incredible amount of time and provides a powerful stimulus for cellular repair. Note: OMAD can be challenging socially and requires you to be very mindful that your one meal contains all the nutrients you need.

4. Extended Fasting (24 Hours and Beyond)

a) 24-Hour Fasts (Eat-Stop-Eat)

This involves fasting from dinner one day to dinner the next. It's a full 24-hour break from food but you still eat every single day. Many people find doing this once or twice a week is highly effective for weight management.

b) 36–48 Hour Fasts

This is where you skip a full day of eating. This allows for total glycogen depletion and very deep levels of ketosis.

c) 3–5 Day Water Fasts

These are significant metabolic events. Day 1 and 2 are usually the hardest as your body transitions. By Day 3, many people report a "fasting high" — intense mental clarity and a total disappearance of hunger.

Breaking the fast: After a multi-day fast, your digestive system is "asleep." Breaking it with a large, carb-heavy meal can be dangerous (Refeeding Syndrome). Start with something small and low-carb: a cup of bone broth, a single egg, or a few olives. When to stop: If you experience true dizziness, heart palpitations, or extreme muscle weakness, stop immediately. Drink some salt water and eat a small meal.

5. Electrolytes — The Critical Factor

Most fasting side effects — headaches, fatigue, muscle cramps — aren't caused by a lack of food, but by a lack of salt. When insulin is low, your kidneys excrete sodium rapidly. As sodium leaves, it pulls potassium and magnesium with it.

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Sodium: The most important. Salt your water or drink a cup of bouillon. UK Recommendation: Marigold Swiss Vegetable Bouillon (available in most supermarkets) is a lifesaver — very low calorie but rich in sodium.

Potassium: Look for Cream of Tartar in the baking aisle — it is purely potassium bitartrate. A quarter-teaspoon in a litre of water provides a good boost.

Magnesium: Look for Magnesium Glycinate, Citrate, or Malate — avoid cheap Magnesium Oxide, which is poorly absorbed and often causes digestive upset. The form matters significantly. A triple-form complex combining bisglycinate, citrate, and malate covers multiple absorption pathways: Magnesium Glycinate 3-in-1 Complex (Ad) — 384mg elemental magnesium per serving, UK-made.

6. Autophagy — The Cellular Repair Process

Autophagy comes from the Greek for "self-eating." It is a natural process where your cells identify and recycle damaged parts. In 2016, Yoshinori Ohsumi won the Nobel Prize for discovering how this works. Research suggests that meaningful autophagy begins around 16–18 hours of fasting and intensifies significantly during 24–48 hour fasts.

7. Other Benefits of Fasting

• Insulin Sensitivity: Fasting is perhaps the most powerful way to "reset" how your body handles blood sugar.
• Growth Hormone: Fasting can lead to a massive spike in Human Growth Hormone (HGH), which helps preserve muscle and bone density.
• Mental Clarity: Once your brain is fuelled by ketones, many people report a "brain fog" lifting.
• Simplicity: No cooking, no cleaning, no shopping for a day. It's the ultimate time-saver.

8. Common Concerns and Myths

"Won't I lose muscle?" No. Your body is designed to protect muscle during short-term fasting using HGH. As long as you have body fat to burn, your body will use that first. Just ensure you eat enough protein in your eating window.

"Won't my metabolism slow down?" Actually, short-term fasting slightly increases metabolism due to the release of noradrenaline. Metabolic slowdown is associated with chronic, low-calorie dieting, not intermittent fasting.

"Can I exercise?" Yes! Many people find training in a fasted state leads to better focus. Just be careful with high-intensity training during very long (3+ day) fasts.

9. How to Start — A Practical UK Guide

1. Week 1: Just stop snacking after dinner. If you finish dinner at 8pm, don't eat again until 8am. (12:12)
2. Week 2-3: Push breakfast back. Try to make it to 10am. (14:10)
3. Week 4: The Goal. Push breakfast back to noon. You are now doing 16:8.

If you feel a headache coming on, drink a cup of bouillon or some salt water first. 90% of the time, that will fix it.

10. Fasting and Low-Carb — The Combination

Fasting and low-carb are two sides of the same coin. Both aim to lower insulin and switch the body to fat-burning mode. If you try to fast while eating a high-carb diet, you will likely find the hunger unbearable as your blood sugar crashes.

Our recommendation is to get your low-carb eating right first. Once you are fat-adapted (usually after 2–4 weeks), you will find that fasting happens naturally.

When it comes to your eating window, the quality of what you eat matters as much as when you eat. In particular, addressing the omega-6 to omega-3 imbalance created by a typical Western diet supports the same anti-inflammatory goals as fasting. A high-strength fish oil taken with your main meal covers this efficiently: Nutravita Omega-3 2000mg — 240 softgels (Ad), providing 660mg EPA and 440mg DHA per serving.