Fast 5 Fasting Tips | Fasting | LCHF

Fasting is getting really popular. The science is now convincing, and the practice of not eating, contrary to what you first hear, is quite fun. For food lovers, the slight deprivation makes eating even more fun. I met a woman the other day who has fasted on Wednesdays for years. She told me she and her husband do it because they love food so much and wanted to enjoy it even more. I think she might be right.

So here are my top 5 fasting tips if you haven’t tried it — expanded with a bit more of the how and why, because the difference between a fast that feels effortless and one that feels like punishment usually comes down to preparation, not willpower.

Key Takeaways

• Fat adaptation comes first. If your body is still running mainly on glucose, fasting will feel like a struggle. Becoming a low-carb, high-fat eater most of the time is the single biggest lever.
• Fasting is a skill, not a personality trait. Social pressure, food cues and habit are the real hurdles — anticipate them and plan around them.
• Do it with someone. A partner, flatmate or friend who fasts alongside you removes the “weird one” problem and makes it social rather than solitary.
• Manage your environment. Hunger is partly a conditioned response to sights and smells. Route around the cues you can avoid.
• Understand the biology. Knowing what autophagy and apoptosis actually are turns fasting from a test of endurance into something you can explain, defend and enjoy.

1. Be Fat Adapted First

Unless you are a fat burner, fasting is going to hurt. The only really effortless way to get there is to be a low carb eater most of the time. This drives the physiology of fat burning over carb burning. Because you have lots of fat to burn (even the leanest of us does), you can go on for a day or two without food no worries.

The reason this matters is straightforward physiology. When you eat a high-carbohydrate diet, your body keeps a ready supply of glycogen (stored glucose) in the liver and muscles, and it is used to topping that up every few hours.

Blood glucose swings, insulin stays relatively high, and the body has little incentive to mobilise fat. Skip a meal in that state and you get the classic symptoms: shakiness, irritability, a gnawing hunger, sometimes a headache. That is not “fasting working” — that is a body that has not been given the chance to switch fuels.

On a low-carb, high-fat (LCHF) way of eating, the picture changes. Insulin levels are lower, the liver’s glycogen store is smaller and more readily drawn down, and the body becomes comfortable oxidising fat and producing ketones from it. Ketones — beta-hydroxybutyrate, acetoacetate and acetone — are not just a waste product; they are a genuinely useful fuel for the brain and other tissues. Once you are producing them at a reasonable rate, the urgency of “I must eat now” fades.

A few practical points on getting fat adapted:

• Give it time. Fat adaptation is not a switch you flip in a day. Most people notice a real difference after a couple of weeks of consistent low-carb eating, and it often continues to improve beyond that.
• Don’t under-eat fat while adapting. The temptation is to cut carbs and cut fat, which just leaves you hungry and miserable. Fat is the fuel that makes the transition tolerable.
• Watch your electrolytes. When you cut carbs and start fasting, the body sheds sodium and water. A pinch of salt in water, or a mug of broth, often fixes the “fasting headache” that people blame on hunger.
• If you are on medication, get advice first. This is not a throwaway line. If you take insulin or a sulfonylurea for type 2 diabetes, or medication for blood pressure, fasting can change your requirements quickly. Speak to your GP or diabetes team before you start — this is exactly the kind of thing the clinicians who write about LCHF, such as those behind the What The Fat? books and the wider low-carb clinical community, are keen for people to get right.

2. Get Psyched — Anticipate the Hurdles

In my experience, there are some social and other hurdles when you aren’t eating. Know that they are coming and be prepared.

The hurdles are rarely about food itself. They are about the moments around food:

• The office morning tea. Someone brings cake. You are the only one not eating. Decide in advance what you’ll say: “I’m fasting today, but I’ll grab a coffee.” Short, cheerful, no lecture.
• The family dinner you can’t move. Shift your eating window rather than skipping the meal entirely. Fasting does not have to mean a rigid 24-hour block; a shorter daily window is a legitimate and often more sustainable version.
• The “are you okay?” concern. People who care about you will worry. Having a one-sentence explanation ready — “It’s deliberate, I’ve read up on it, I feel great” — defuses most of it.
• The evening habit. For many people the hardest part is not hunger but the ritual of eating while watching television or winding down. Replace the ritual, not just the food: a herbal tea, a walk, a bath.

Getting psyched also means picking your moment. Starting a fast on a day you have a work lunch, a birthday dinner and a long commute is setting yourself up to fail. Start on a quiet day. If you’re new to it, a 16-hour overnight fast (essentially skipping breakfast and eating lunch and dinner) is a far gentler entry point than a multi-day fast, and for many people it delivers most of the benefit with a fraction of the difficulty.

3. Get At Least Someone Else to Do It Too

If you live in a family then your partner is critical to this. Who wants to be the weird one here? Obviously you’ll feed your kids and there’s a few hurdles there, but the two of you sitting it out and having a quiet fruit tea will be way more fun than going it alone.

There is a real behavioural principle at work here. Humans are social eaters; we take our cues about when, what and how much to eat from the people around us. Fasting alone means fighting those cues constantly. Fasting with someone means the cues work for you instead of against you.

Some ways to make this easier:

• Agree the plan together. Which days, which meals, who’s cooking for the kids. Ambiguity is where resentment creeps in.
• Find a community if you don’t have a partner who’s keen. Online low-carb and fasting communities, workplace buddies, or a friend who’s curious — anyone who’ll check in.
• Don’t evangelise. The fastest way to make fasting socially painful is to turn every meal into a debate. Answer questions if asked, then move on.

4. Actively Avoid the Smells and Sights of Really Yummy Food

You and I are humans and when we see and smell food we have the start of a chain reaction of getting ready to eat. It’s as simple as walking past a cafe with everything spilling out onto the street including the food smells. Take another way around. It’ll help.

This is not weakness — it’s cephalic phase response, the body’s anticipatory preparation for eating, triggered by the sight, smell and even the thought of food. Salivation, gastric acid secretion and hormonal changes all kick in before a single bite is taken. You cannot will that away, but you can reduce the triggers:

• Change your route. Walk the block that avoids the bakery.
• Change your screen. Food advertising and cooking shows are designed to make you hungry. During a fast, they’re working against you.
• Change your kitchen habits. If you’re cooking for others, cook something simple and eat-proof, or cook ahead. Standing over a simmering pot for an hour is a test you don’t need to take.
• Use distraction deliberately. A walk, a project, a phone call — anything that occupies the hands and the mind. Hunger waves come and go; they are not a steadily rising tide.

5. Know the Science

Okay, I’m a research scientist, so I’m biased, but to me if you understand what fasting does for your brain and body from the cell up then it makes the whole process much more enjoyable. You’ll feel good about explaining to others what you are doing, bring in others with you, and feel virtuous about what you are achieving.

Test: Can you explain to others what autophagy and apoptosis are?

Autophagy — the self-cleaning program in the cell, initiated by the (lack of) nutrient stress from fasting. The particular cellular organelle is called the lysosome, and it moves around the cell scavenging bits and pieces and generally tidying up and repairing the cell. The word literally means “self-eating,” and the discovery of the mechanisms behind it earned Yoshinori Ohsumi the Nobel Prize in Physiology or Medicine in 2016. In practical terms, autophagy is the cell’s recycling and quality-control system: damaged proteins and worn-out organelles get broken down and their components reused. Fasting is one of the more potent natural triggers of it.

Apoptosis — the process where old cells which are past their “use by date” are recycled and the nutrients recycled. The lack of food (fasting) can help this process. Apoptosis is programmed cell death — not a failure, but a deliberate, orderly dismantling of cells the body no longer needs. It is how the body clears out cells that are damaged or potentially dangerous, and it is distinct from necrosis, which is messy, uncontrolled cell death.

Understanding these two processes gives you a mental model for what you’re doing when you skip a meal. You’re not just “not eating.” You’re giving your cells a window in which maintenance work can happen — clearing debris, recycling components, and removing cells that have outlived their usefulness.

Putting It Together: A Practical Starter Framework

If you’re deciding how to begin, this is a reasonable way to think about it:

Approach	Typical pattern	Best for	Main caveat
Time-restricted eating	12–16 hours fasting daily (e.g. skip breakfast)	Beginners; fitting fasting around a normal social life	Easy to drift into constant snacking in the eating window
24-hour fast	One full day per week, or one skipped-meal-to-skipped-meal cycle	People already fat adapted who want a deeper metabolic stimulus	Social logistics; needs planning around family meals
Multi-day fast	2–3 days, occasionally	Experienced fasters, often with clinical supervision	Not for beginners; medical advice essential if on medication

The general principle: start shorter than you think you need to, and only extend once the shorter version feels genuinely easy. Fasting is a skill you build, not a challenge you survive.

Sources & Further Reading

• Fasting — Wikipedia: Fasting is the act of refraining from eating, and sometimes drinking. However, from a physiological context, “fasting” may refer to the metabolic status of a person…
• Intermittent fasting — Wikipedia: Intermittent fasting (IF) is any of various meal timing schedules that cycle between voluntary fasting (or reduced calorie intake) and non-fasting over a given period…

How many hours do you fast on the Fast 5 diet?

On the Fast-5 diet, you fast for 19 hours each day. The method involves eating within five consecutive hours and fasting for the remaining 19 hours of the day. Only calorie-free beverages are permitted during the fasting period, and the five-hour eating window can be adapted to your schedule.

Source: shunketo.com

What are the best foods to eat on a low-carb high-fat diet during Fast 5?

Low-carb foods include meat, fish, eggs, vegetables and natural fats, like butter. Meat of any type, fatty fish such as salmon, mackerel, sardines or herring, and eggs prepared in any way are recommended.

Natural fats and high-fat sauces like butter, cream, Béarnaise or Hollandaise can be used, along with coconut fat or olive oil. Vegetables that grow above ground, including cauliflower, broccoli, cabbage, spinach, asparagus, zucchini, eggplant, olives, mushrooms, cucumber, avocado, onions, peppers and tomatoes, are lowest in net carbs.

Source: dietdoctor.com

Can you drink coffee or tea while fasting on Fast 5?

Yes, black coffee and tea are generally fine to drink while fasting. Both are low in calories, and black coffee contains less than 3 calories per cup, so moderate amounts are unlikely to break a fast. Keep them plain, since added sugar, milk, or sweetened drinks can reduce fasting benefits. Caffeine intake should be watched to avoid side effects, and serving size matters.

Source: healthline.com

Frequently Asked Questions

Do I need to be on a low-carb diet to fast successfully?

No, but it makes an enormous difference. On a high-carb diet your body is geared to burn glucose and expects refuelling every few hours, so fasting triggers genuine hunger and discomfort. Once you are fat adapted through consistent LCHF eating, the body can switch to burning fat and producing ketones, and fasting becomes far more comfortable. Most people find the two practices reinforce each other.

How long should my first fast be?

Start with something modest — a 12- to 16-hour overnight fast, which for most people simply means delaying breakfast. If that feels easy after a week or two, extend it. There is no prize for suffering through a long fast on your first attempt, and a bad first experience is the most common reason people give up.

Is it safe to fast if I have type 2 diabetes?

Fasting can be genuinely beneficial for many people with type 2 diabetes and insulin resistance, but it needs to be done with medical guidance, especially if you take insulin or a sulfonylurea. Those medications can cause hypoglycaemia when you fast, and doses often need adjusting. Talk to your GP or diabetes team first — this is a case where a short conversation prevents a serious problem.

What can I drink while fasting?

Water, plain tea, and black coffee are the usual choices, and they don’t meaningfully interrupt a fast for most people. A pinch of salt in water or a mug of clear broth helps with electrolytes and staves off headaches. Anything with calories — including milk, cream, juice and most “diet” drinks with sweeteners, depending on your approach — is generally best avoided if you want a clean fast.

Will fasting make me lose muscle?

For most people doing shorter fasts, no. The body has ample fat to draw on and preferentially uses it. Muscle loss becomes a bigger concern with prolonged fasting, very low protein intake, or fasting combined with heavy training and inadequate overall nutrition. If you’re doing resistance training, keep protein adequate in your eating window.

What if I feel dizzy or unwell during a fast?

Stop and eat. Fasting should feel manageable, not alarming. Dizziness, palpitations, confusion or feeling faint are signals to break the fast, rehydrate and consider whether you need electrolytes or medical advice. Fasting is a tool, not a test of endurance — there is always another day.