I Was Told Fasting Was Dangerous. I Fasted for 10 Days. Here’s What Happened.

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I was told that what I was about to do was dangerous. My GP had the blood tests to prove it — just not in the direction they expected.

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On the 9th of January 2025 I stopped eating. For eleven days. I was on multiple medications at the time. And I documented everything, every single day, with my GP’s knowledge.

I’m Neil. Fifty-two years old, NHS blood test records going back to 2012, and off all medications since February 2024. In the next fifteen minutes I’m going to walk you through exactly what happened during that eleven-day fast — the biomarkers, the daily data, the moment the GP looked at the results. And if you’ve been told fasting isn’t for people on medication, this is worth understanding — whatever your situation.

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We’re going to start with what the blood tests looked like before — because that context is everything. Then I’ll walk you through the eleven days: what I tracked, what the data showed, and where the numbers went that I didn’t expect. And then the two blood tests after — one at the GP in February 2024, one two years later — and what they said about the whole question of whether this was dangerous. We start with the January morning I decided to begin.

THE SCIENCE (5-7 minutes)

9th of January, 2025. Fifteen stone two. That’s where I started.

I want to explain why someone on multiple medications — statins, gout medication, asthma inhalers, antihistamines — would decide to stop eating for eleven days. And to do that, I need to explain what was happening in the body during those eleven days. Because the word “dangerous” only makes sense if you understand the mechanism. And once you understand the mechanism, the question changes.

What actually happens when you stop eating

Most people think of fasting as deprivation. Running on empty. Your body panicking. The medical establishment version of this is starvation mode — the idea that going without food sends your system into crisis.

That belief is wrong. And here is why.

Think of your body’s energy system like a house with two fuel sources. You’ve got mains gas — that’s glucose, the quick stuff. Instant heat, easy to use. Most of us run on it all day, every meal topping it up. There’s also a wood burner in the corner. Hasn’t been lit in years. But it’s there. Ketones — fuel made from body fat. When the gas gets cut off, the house goes cold for a bit while you figure out how to light the wood burner. Day one or two, it’s smoky, inefficient, you’re not sure this is going to work. Day three — roaring fire. House warmer than it’s been in years. And here’s the thing you hadn’t noticed: there’s a forest of logs in the garden. Body fat. Enough to run on for weeks.

That’s ketosis. Not starvation. A fuel switch.

The starvation model says you’re running out of money. The reality is more like this: starvation is zero pounds in your account, bailiffs at the door. Fasting is fifty thousand pounds in a savings account, choosing not to withdraw from the current account for eleven days. Your body isn’t panicking. It’s just withdrawing from savings instead. The money’s there. It’s just in a different account. Claiming fasting equals starvation is like saying you can’t buy a coffee because you left your wallet at home — when you’ve got fifty grand in the bank. Your body has the fuel. It’s just learning to access it.

Now. What happens on day one, two, three — because this is where people quit.

Day one feels like running a marathon in work shoes. Uncomfortable. Strange. Energy inconsistent. Your body is burning through the last of the glycogen in your liver and muscles. By day two, it’s gone. Blisters forming, energy’s low, you’re questioning everything. This is normal. This is adaptation, not damage.

Day three is different.

There’s a moment I’ve experienced across multiple extended fasts — I call it The Quiet. You’re standing in the middle of a busy train station. Announcements blaring, people rushing past, noise everywhere. Hunger signals. Irritability. That low-grade discomfort. Overwhelming. And then — you sit down, close your eyes for ten minutes. Open them. Silence. The station is still busy. But you can’t hear it anymore. You’re watching from behind glass. Calm. Detached. Clear. That’s Day 3. The Quiet arrives. Hunger’s gone. Mental fog lifts. You’re floating six inches above the chaos.

That isn’t me being poetic. That’s a physiological shift. Ketones — the brain’s alternative fuel — are cleaner-burning than glucose. Once you’re running on them properly, mental clarity often improves. This is documented. It’s reproducible. And it only happens if you get past day two.

The autophagy question

Now here’s where the research gets interesting — and where I had to update my own assumptions.

There’s a body of fasting research that puts autophagy — cellular cleanup, damaged proteins clearing out, old cellular junk being recycled — at the 48 to 72-hour mark. That’s what I’d read. That’s what most fasting content says. Wait 48 hours, then the good stuff starts.

Research now suggests that’s not quite right. Autophagy isn’t a switch. It’s a gradient. It starts ramping up around 18 to 24 hours. Peaks deeper in — yes. But the cellular repair process begins much earlier than the 48-hour rule implies.

I have my own data on this. Day 8 of my 70-day reset. Twenty-six hours fasted. Glucose 77 mg/dL, ketones 1.6 mmol/L, GKI 2.7. That’s therapeutic ketosis range — at 26 hours, not 48. The cleanup crew was already on site. The 48-hour convention is probably based on less metabolically flexible people. After months of fasting practice, the switch happens faster.

That matters whether you’ve been told you have a metabolic condition or not. The mechanism — the body’s ability to enter therapeutic ketosis and begin cellular repair — develops over time. It runs in the background. Understanding it gives you options before any GP conversation forces the issue.

The medication question

Here’s what everyone with a medical history wants to know. What about medication? Is fasting safe on prescription drugs?

I’m not your GP. What I can tell you is what I did, what I tracked, and what the results showed.

Before the January fast, I had a blood test. Kidney function: eGFR over 90 — excellent. That matters because the kidneys are the first thing people worry about during extended fasting. Mine were fine going in, and I monitored throughout.

Michael Mosley and Tim Spector — a medical doctor and an epidemiologist — agreed on something without hesitation in a conversation I’ve logged in my evidence library. Lifestyle changes can be as powerful as medicine. Not lifestyle changes as a nice supplement to medicine. As powerful as. That’s a significant claim from two credible medical professionals. And it maps onto what my blood tests eventually confirmed.

The safety question isn’t “is extended fasting dangerous?” The real question is “is extended fasting dangerous for this person, with this blood work, with this monitoring?” Those are completely different questions.

MY EXPERIENCE (4-6 minutes)

9th of January, 2025. Fifteen stone two pounds. I stopped eating.

I want to be straight with you about what that first day felt like. Strange is probably the right word. Not painful. Not desperate. Just… unfamiliar. I’d done 18:6 fasting for months by this point. I’d done 24-hour fasts. I’d done 48-hour fasts. This felt like a longer version of something I already knew.

Day one: energy 7 out of 10. Mood 7. Hunger present but manageable. Glucose stable. That’s metabolic flexibility working — months of 18:6 training meant my body already knew how to access fat. The fuel switch wasn’t starting from scratch.

Day two was harder. That’s honest. Energy dipped. I felt cold. Not dangerously cold — I’ve logged this before, that cold sensation when your body is switching fuel sources and hasn’t hit full efficiency yet. Annoying. Uncomfortable. Not alarming.

Day three — The Quiet arrived. Exactly as I’ve described it. Hunger gone. Mental clarity up. I’ve documented this across five, seven, fourteen-day fasts. It arrives at the same point every time. Your brain switches to ketones and things get… easier. Quieter.

By day eight, I was taking daily biomarker readings. Glucose 77. Ketones 1.6. GKI 2.7. Therapeutic ketosis at 26 hours of that day’s fast. That’s the gradient the research describes — not a switch at 48 hours. My body had learned to get there faster. That pattern — hitting therapeutic ketosis earlier as metabolic flexibility improves — is one the data shows across bodies that have been training this way consistently. Not just mine.

The weight data from WMTWL-3223: I started at 15 stone 2 pounds. By day 10 hours 14, I was at 13 stone 12 pounds. One stone four pounds in eleven days. I want to be careful about this number because about half of that is water and glycogen leaving the body — that’s real weight that comes back during refeed. The metabolic work, the cellular repair, the biomarker changes — those don’t come back.

The two GP moments

Twelve weeks after Boxing Day 2023, I sat in my GP surgery with the first blood test since stopping all my medications. I was nervous. I’d stopped statins, gout medication, asthma inhalers, antihistamines — all of it — and I’d been fasting. My GP opened the results.

He paused. Looked up. Cholesterol stable. Uric acid optimal. Inflammatory markers down. And then he said something I didn’t expect: “Whatever you’re doing, keep doing it.”

No lecture. No concern. Just data talking.

The second moment came in December 2025 — nearly two years after I started. A letter from my GP. Confirming blood tests. The letter said I was off the risk register for everything they’d been monitoring. Every marker in optimum-normal range. Twenty months without any medications. Someone who’d smoked heavily in his twenties, been at eighteen stone, been one point from diabetic, had high cholesterol, gout, asthma, kidney and liver markers being watched. Now? Off the list. Entirely.

That letter is in my evidence database as WMTWL-MOM-313. I didn’t frame it as a win for fasting specifically. It’s a win for fixing the inputs — fasting, real food, simple movement, enough sleep. But eleven days in January 2025 was part of that arc.

The one thing I’d add: I rang my GP before I started. I didn’t ask permission — I’m an adult and it’s my body. But I wanted to go in with eyes open. I checked my bloods, I knew my kidney function was good, I knew what to monitor. The red flags I was watching for: dizziness that doesn’t pass, heart rate spiking above 120, significant blood pressure drop. None of those appeared. The fast was uneventful — in the best possible way.

SUBSCRIBE PROPOSITION BEAT

Six medications. Statins, gout pills, asthma inhalers, allergy tablets — the lot. I stopped all of them in 2024. Not because a YouTuber told me to — because thirteen months of blood tests told me the inputs were working. If documenting that kind of thing properly sounds worth following, subscribe.

WHAT I’D ACTUALLY CHANGE (2-3 minutes)

If I were starting an extended fast from scratch — knowing what I know now — there are three things I’d do differently.

First, I’d have better biomarker data going in. I had my blood tests, but I didn’t have daily glucose readings from the weeks before. The baseline matters. If your fasting glucose is already elevated going in, that changes how you read the numbers during the fast. Get a baseline. Two weeks of morning readings before you start anything extended.

Second, I’d start shorter. The 11-day fast wasn’t my first. It was maybe my fifth or sixth extended fast. The first one was 48 hours. Then 72. Then five days. The body learns. The metabolic flexibility that let me hit therapeutic ketosis at 26 hours on day 8 — that came from months of practice. If you’re thinking about extended fasting and you haven’t done a clean 48-hour fast yet, start there.

Third — and this is the one people skip — I’d pay more attention to the refeed. Breaking an eleven-day fast is not the moment to eat a massive meal. Your digestive system has been on holiday. Feet up, not a care in the world. Monday morning, you don’t storm back into the office and immediately present to the board. You ease in: bone broth, light soup to start. A couple of hours later, something small and easily digested. By the evening, a normal meal. Rush it — skip straight to the full roast dinner — and your gut goes on strike. Cramps. Bloating. A deeply unpleasant afternoon. Ease in. Respect the office return.

Practically: if you want to test extended fasting safely, here is the minimum effective dose.

Do a 24-hour fast first. One meal, then nothing until the same time the next day. Log your energy, your mood, your hunger — just notes in your phone. See how you feel. That’s your baseline. If 24 hours felt manageable, try 48. Add electrolytes — salt and potassium in your water, magnesium before bed. The electrolyte piece is non-negotiable on anything beyond 24 hours. Your body is a car battery. Water alone is distilled water in the battery — it won’t hold a charge. Electrolytes are what makes it work.

If you’re on medication — speak to your GP before any extended fast. Not because you need permission. Because you need information. Know your kidney function. Know your blood pressure baseline. Know what your specific medication does during a fasting state. That conversation takes twenty minutes and removes ninety percent of the risk.

Red flags to stop and seek advice: dizziness that doesn’t pass when you sit down, chest discomfort, heart rate sustained above 120, significant confusion. Any of those — break the fast, eat something, ring your GP or NHS 111.

The 7-Day Fasting Blueprint is in the description. It covers the protocol I use, including how I approach refeed. Free download. Link below.

CTA + SAFETY (1 minute)

If extended fasting is something you’re considering — or you’re just curious what a proper tracked protocol looks like — the 7-Day Fasting Blueprint is in the description. It’s free. It covers the structure, the electrolytes, the red flags, the refeed. Everything I wish I’d had written down clearly when I started.

One thing I want to be clear about before you go. This is educational content. Not medical advice. Everything I’ve shared is what happened to me, tracked against my own blood tests, with my GP’s knowledge. Before you change your fasting pattern, your diet, or your medication — speak to your GP. Especially if you’re on diabetes medication or blood pressure medication. Fasting changes how those drugs work. The conversation is worth having before you start, not after.

All of this is documented. Blood tests, biomarker logs, GP letters. Not because I’m trying to impress anyone — because data is the only thing that separates genuine progress from wishful thinking.

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