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What is The Fast 800?

The official home of 5:2 and intermittent fasting

Developed by Dr Michael Mosley and a team of nutritionists and doctors following the latest science, our step-by-step programme helps you lose weight fast and keep it off. With tailored meal plans, workouts and support we make it easier to get healthier and activate your body’s ability to burn fat.

Create sustainable habits

Feel fitter

Improve blood sugars

Lose weight

The Fast 800 Programme

Live better and longer

Reduce risk of chronic disease

What our members say

We've helped over 100,000 people just like you lose weight, keep it off and improve their health

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What's included

Personalised meal plans to suit your goals

  • Vegetarian and Keto options
  • Nutritionist-made with macros and calorie counts

200 guided workouts, no equipment required

  • Low impact beginner to advanced fitness
  • Resistance, cardio, yoga and pilates

800+ simple and tasty recipes

  • Automated shopping lists
  • Satisfying portions and a range of global cuisines

Real support, as you need it

  • Member-only Health Coach support
  • Be part of an interactive cohort

Member-only app for ultimate convenience

  • Weight loss tools in the palm of your hand
  • Use your programme any time, anywhere

Behaviour change course and mindfulness

  • Science-backed support to make new habits stick
  • 40+ guided mindfulness videos

What does it cost?*

12 week programme

( – select your currency when you sign up)

This gives you access to the 12-week programme plus one extra month of membership to The Fast 800. After that, your ongoing monthly membership is . You can cancel this monthly membership at any time. *This price structure is only available via the website.

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Start your personalised programme now with your first 7 days absolutely free

Sign up today and your free trial begins immediately. Week 1 of your programme will start on:

Monday 22nd July

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How it works

Our flexible dietary approaches are designed to suit your goals and circumstances. Learn The Fast 800 way so you can tweak your approach as your needs change. It's more than a diet - it's a sustainable approach to a healthy lifestyle.

Personalise your programme

  • Sign up and take our assessment
  • Your programme is set with the right approach for your goals and circumstances
  • Switch easily between each approach as your needs change

Lose weight and reprogramme your body

  • Follow your meals and exercise plan
  • Learn the science as you go
  • Engage with your cohort and health coaches
  • Track your progress

Learn to live a healthier life

  • Incorporate The Fast 800 healthy habits into your daily routine
  • Tweak your programme settings to suit you best
  • Sustain your results

With delicious meals to enjoy, not endure

Our low-carbohydrate, Mediterranean-style meals are nutritionally balanced to keep you fuller for longer and promote rapid fat burning. They are easy to prepare and of course, taste great!

As seen in

Dr Michael Mosley explains the biology behind weight loss

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The science behind The Fast 800

The biology behind weight loss

Burning energy 101

Your body mainly runs on two types of fuel: sugar (in the form of glucose) and fat. When it uses glucose, fat is stored in the body.

The sugar problem

When you have more glucose than your body needs for energy, it eventually gets stored as body fat. This commonly happens when someone eats a high-carbohydrate (sugar & starch) diet.

How to burn fat

When you eat a low-carb diet, your body has less glucose to run on. So, it starts to use your fat stores instead. You can fast-track this process by intermittent fasting.

The Fast 800 Programme will teach you how to combine delicious food with intermittent fasting so you can burn through excess fat stores and return your body to health.

What to expect while following The Very Fast 800

Click on the timestamps to see how the typical body responds over 12 weeks to our most popular approach

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Blood sugar

You may see a stabilisation

How you feel

Less hungry, with more energy and motivation

Weight loss

Potential weight loss

Body fuel


What's happening?

The body is likely in ketosis, and is adapting well to using fat as fuel. Motivation to continue will increase as the scales start to shift. Weight loss will differ from person to person.

Blood sugar

You will see a stabilisation

How you feel

You may feel more positive

Weight loss

Less hungry with more energy and motivation

Body fuel


What's happening?

Metabolic health is improving. Your body is using energy more effectively and is able to switch between glucose and fat for fuel. Weight loss may stall for a few weeks, which is normal as the body continues to adjust.

Blood sugar

You should see a stabilisation

How you feel

Sleeping well. Sustained energy and motivation

Weight loss

Sustainable weight loss

Body fuel


What's happening?

You're in a good routine and have sustained energy for exercise. Your metabolism switches between glucose and fat burning easily. You may see a return to stable weekly loss of around 1lb/0.5kg a week.

Blood sugar

You should see a stabilisation

How you feel

Strong and motivated to continue with your health goals

Weight loss

Overall, significant weight reduction

Body fuel


What's happening?

Your body can now use the energy from your food efficiently. Insulin sensitivity has improved, meaning less insulin is required to control blood sugar levels. Your health is on track and you can feel the difference!

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The Fast 800: The Programme For Fast Weight Loss in the UK

What is The Fast 800?

A nutrition and lifestyle programme to activate your body’s natural ability to burn fat rapidly and facilitate your journey to long-term, sustainable weight loss.

Developed by nutritionists and doctors, including Dr Michael Mosley, following the latest science. The Fast 800 is an independently validated programme designed to kick-start your body’s own weight-loss mechanisms and help you lose weight quickly, improve your metabolic health and live longer.

Our step-by-step programme is simple to follow, providing delicious recipes, designed to flip your metabolic switch and burn through your fat stores.

Your 12-Week Weight Loss Plan Awaits

Starting a weight loss journey is a big step. Our 12-week weight loss programme is here for people who want clear results in an easy-to-follow way. With this 12-week weight loss plan, you get a complete guide that looks at exercise and eating right, making sure you make the most of each day.

The good thing about a 12-week weight loss workout plan is that. As the weeks go by, If you’re ready to start this exciting journey, our 12-week diet plan is here to guide you. Let’s dive into what it offers.

Personalised for Every Individual

Everyone’s journey to weight loss is different, and that’s why our 12-week weight loss programme is designed to fit individual needs. By merging the main ideas of weight control with a plan made just for you, we provide a 12-week weight loss plan that works for everyone and yet feels personal.

Our members often say that this personalised approach helps them to feel seen, supported, and inspired as they move forward in their 12-week weight loss journey, seeing real changes as they go.

Why Opt for Our Comprehensive 12-Week Weight Loss Programme?

Choosing the right time to embark on your weight loss journey can make all the difference. Our 12-week weight loss plan has been thoughtfully crafted to offer an optimal duration. With the 12-week weight loss programme, there’s ample opportunity for you to establish and reinforce healthy habits. Yet, it’s succinct enough to ensure you remain motivated and consistently observe the transformative results you crave.

A Well-Defined Roadmap

Our 12-week diet plan paired with the 12-week weight loss workout plan provides a clear and comprehensive guide. Each stage is meticulously planned out, getting rid of any guesswork. So, with every day that passes, you’ll be confidently moving forward, certain of your next step.

Witness Your Transformation

The beauty of a 12-week weight loss journey is its tangible results. As you progress week by week, you’ll not only feel the difference but see a rejuvenated version of yourself emerging.

Science-backed Approaches

What sets our 12-week weight loss programme apart is its foundation in scientific research. This commitment to evidence-based methods, which are also delicious and achievable, ensures you’re in reliable hands as you journey towards a healthier you.

What does it cost?*

12-week programme

$199 $159 AUD

(£119 £95 GBP / $149 $119 USD – select your currency when you sign up)

This gives you access to the 12-week programme plus one extra month of membership to The Fast 800. After that, your ongoing monthly membership is £12 GBP / $22 AUD / $15 USD. You can cancel this monthly membership at any time. *This price structure is only available via the website.

Navigating Through Our 12-Week Weight Loss Programme

As you embark on our 12 week weight loss plan, each week promises fresh challenges and notable milestones. Here’s a brief overview of your journey:

Weeks 1-4: Foundation Phase of the 12-Week Weight Loss

  • Unpack the foundational principles of nutrition and physical activity.
  • Tune into your body’s specific requirements and lay down realistic objectives.
  • Keep an eye on your starting weight loss achievements and take a moment to rejoice in those initial successes.

Weeks 5-8: Intensification Phase of the 12-Week Weight Loss Workout Plan

  • Amp up your exercise routines by incorporating more intricate workouts.
  • Grasp the intricacies of weight loss science, including insights into metabolism and the role of calories.
  • Stay committed to monitoring your advances and fine-tuning your objectives as you proceed.

Weeks 9-12: Consolidation Phase of the 12-Week Diet Plan

  • Take the time to reinforce and make permanent the beneficial habits you’ve picked up during the program.
  • Prioritise the retention of your weight loss accomplishments, ensuring you don’t backtrack.
  • As the 12 week weight loss phase draws to a close, gear up for a lifestyle that not only retains but enhances the positive changes you’ve achieved.

Free 7-day trial

Start your personalised programme now with your first 7 days absolutely free.

The food

Delicious meals to enjoy, not endure

All approaches of The Fast 800 incorporate low-carbohydrate, Mediterranean-style meals that keep you fuller for longer and promote rapid fat burning. Our meal plans are nutritionally balanced, include a variety of easy recipes and of course, taste great!

Our three core approaches

Finding a programme that works for you is so important in maintaining a healthy lifestyle long-term.

Dr Michael Mosley explains the biology behind weight loss:

How your body burns energy

Your body runs on two different types of fuel: glucose (i.e. sugar) and fat. Your body only turns to major fat burning for fuel when glucose supplies (which are stored mainly in your muscles and liver in the form of glycogen) start to run down.

The glucose problem

Many of the foods we eat are high in carbohydrates, which contain more glucose. If you eat a lot of high carb snacks or food during the day, your body will be busy burning glucose, not your fat stores. When there’s more glucose in the body than can be used, it triggers fat storage.

The key to burning fat

Less carbs. By eating less carbohydrates as part of your 12-week diet plan, your body naturally has less glucose to burn.

Less calories. By consuming about 800 calories each day, your body can swiftly burn through your glycogen stores and start burning fat instead.

Less often. By eating less frequently, your body can remain in the fat burning zone for longer.

Embark on Your 12-Week Weight Loss Journey Now

If you’re set to dedicate yourself, to invest the effort, and to savour the benefits, our 12-week weight loss plan is ready for you. Embrace the 12-week weight loss workout plan and the 12 week diet plan, paving the way to a fitter, more healthy version of yourself.

12 week weight loss plan for better health

The Fast 800 is the UK’s leading destination for fast and effective weight loss. Our scientifically-backed weight loss programme is designed to help you achieve your health goals swiftly and sustainably. Whether you’re looking for quick weight loss solutions or a comprehensive online weight loss program, The Fast 800 offers a personalised approach to meet your unique needs.

Our Programmes

  • The Fast 800 Online Programme: Our innovative online weight loss program is tailored to provide individualised support, guidance, and resources. It combines the latest in nutritional science with practical meal plans, expert advice, and a supportive community.
  • Rapid Weight Loss: Experience significant results with our approach to fast weight loss in the UK. Our programme is rooted in scientific research and focuses on high-impact strategies to kickstart your weight loss journey.
  • Long-Term Health Management: Beyond quick weight loss, our focus is on long-term sustainable health. We provide tools and resources to maintain your weight loss, improve overall health, and enhance lifestyle habits.

Experience the power of change with The Fast 800. As a leader in fast weight loss in the UK, we are committed to guiding you through a journey of quick and effective weight loss. Our tailored online weight loss programs are designed to fit your lifestyle, ensuring sustainable success. Join The Fast 800’s weight loss programme today and start your journey towards a healthier, happier you. Your transformation awaits!

Start The Fast 800 Weight Loss Programme Today

Embark on your health journey today with The Fast 800 – the ultimate destination for fast weight loss in the UK. Join our comprehensive weight loss programme and be part of a thriving community benefiting from our online weight loss programs. Together, we’ll achieve quick weight loss results while laying the foundation for lasting health and wellness. The Fast 800 is more than a diet; it’s a pathway to a healthier, more vibrant you.

Typical results from The Fast 800

Based on data collected from 23,000 members

Weight loss

6kg 3 mths

Members following the online programme for at least three months lost an average of 6kg

7.3kg BMI > 30

Members who started with obesity (BMI >30) lost an average of 7.3kg after three months

Long term sustained weight loss

Waist circumference reduction

Improved blood sugar levels

Lower HbA1c levels

Frequently Asked Questions

Browse through our most commonly asked questions

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How much does the programme cost?

What's included in the Programme?

How does the free trial work?

Who should avoid a low calorie diet or fasting?

How much weight will I lose?

Can I re-start the 12-week Programme after I start?

When does Week 1 start? Why is there "prepare" time?

Why 800 calories?

Do I have to give up coffee, smoking or alcohol?

Still got questions? Please visit our full FAQ page here or contact us and we’ll get back to you!

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