A programme based on the science of rapidly burning body fat
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Developed by nutritionists and doctors, including Dr Michael Mosley, following the latest science. The Fast 800 is an independently validated online 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.
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Best for Rapid weight loss
A short-term kick-start to improve metabolic health until a healthy weight is achieved, or for up to 12 weeks. Keto variations are available.
Best for Gradual weight loss
Regular intermittent fasting for an effective, gradual way to lose weight or keep it off long-term.
Best for Long-term metabolic health
A long-term maintenance approach for weight management and improving metabolic health.
Click on the timestamps to see how the typical body responds over 12 weeks to our most popular approach
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Begins to stabilise
Hungry
Unchanged
Glucose
The initial adjustment to the programme might feel difficult as your body is used to quick sources of energy for fuel. Remember that you will adjust so stick with it.
Continues to stabilise
Potentially hungry
Unchanged
Glucose
The initial adjustment to the programme might feel difficult as your body is used to quick sources of energy for fuel. Remember that you will adjust so stick with it.
Continues to stabilise
Fatigued
Unchanged
Glucose
As you adjust to this new way of eating, you might experience some symptoms such as fatigue. Stay hydrated and increase your non-starchy vegetable intake and this should pass.
Continues to stabilise
Longer breaks between meals starts to feel easier
Potentially drops due to water loss
Glucose or fat
You will continue to adjust to this new way of eating, for some it takes longer than others. Be patient, and stay hydrated.
You may see a stabilisation
Feeling more positive. Energy begins to improve!
Potential drop, due to water loss.
Fat
Blood glucose and insulin levels start to fall as the body uses up stored energy from your liver and muscles. For some people, ketosis may start around this time. ‘Fruity’ breath, an increase in urination and increased feelings of energy is normal, as your body begins to run on ketones.
You may see a stabilisation
Less hungry, with more energy and motivation
Potential weight loss
Fat
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.
You will see a stabilisation
You may feel demotivated if experiencing a plateau
Potential weight loss, or stabilisation
Fat
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.
You should see a stabilisation
Sleeping well. Sustained energy and motivation
Sustainable weight loss
Fat
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.
You should see a stabilisation
Strong and motivated to continue with your health goals
Overall, significant weight reduction
Fat
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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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.
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.
Less carbs. By eating less carbohydrates, 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.
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Get started for freeAll 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!
Access your meal plan, shopping list, recipes, exercise plan and Health Coaches any time, anywhere.
Personalised meal plans to support three meals or two meals per day
Automated shopping lists
600+ tasty and simple recipes
Vegetarian and non-vegetarian options
Flexible recipes when cooking for others
Variable approaches to suit your lifestyle
12-week guided exercise plans (beginner to advanced)
Low impact workouts for those new to exercise
Exercise library including resistance training, HIIT workouts and stretching
Multiple progressive Pilates plans
All can be done in your living room and with no equipment
A thriving Community platform to connect with like-minded members
Access to online health coaches
Exclusive health coach content including videos and challenges
Access to our extensive and exclusive learning centre
Tools & trackers to manage your goals and progress
Personalised meal plans to support three meals or two meals per day
Automated shopping lists
600+ tasty and simple recipes
Vegetarian and non-vegetarian options
Flexible recipes when cooking for others
Variable approaches to suit your lifestyle
12-week guided exercise plans (beginner to advanced)
Low impact workouts for those new to exercise
Exercise library including resistance training, HIIT workouts and stretching
Multiple progressive Pilates plans
All can be done in your living room and with no equipment
A thriving Community platform to connect with like-minded members
Access to online health coaches
Exclusive health coach content including videos and challenges
Access to our extensive and exclusive learning centre
Tools & trackers to manage your goals and progress
Start your 12-week personalised programme with your first 7 days absolutely free
Next programme start date:
Monday 5th June
Free trial
The DIAMOND Study performed by Oxford University and Dr Clare Bailey looked at the feasibility of using an 800 calorie, low-carb, med-style diet as a treatment for people with type 2 diabetes.
After eight weeks the average weight loss was 9.5kg, sustained over the course of the trial.
Results also included a significant drop in blood sugars, blood pressure and the use of medication.
Based on data collected from 23,000 members
6kg 3 mths
Members following the online programme for at least three months lost 6kg
7.3kg BMI > 30
Members who started with obesity (BMI >30) lost 7.3kg after three months
Members with a BMI ≥ 30 were likely to sustain an average weight loss of 8.7kg at 12 months.
Members with a BMI ≥ 30 saw a significant reduction (on average 4.7cm after 12 weeks) in waist circumference, which is linked to significant health benefits.
Of members with pre-diabetes with a BMI ≥ 30, 61% had blood sugars returned to normal after 12 weeks.
53% of members with type 2 diabetes had blood sugar levels that were no longer in the diabetic range after 12 weeks.
55% of members with type 2 diabetes, but a healthy BMI, saw their blood sugar levels reduce to be outside of the diabetic range.
The average decrease in HbA1c values within the diabetic member group was 28 mmol/mol, which is clinically significant.
Since 2018, we've seen over 70,000 members complete our 12 week programme. Here’s what some of them have to say...
"The Fast 800 is the only diet I've done that’s given me the knowledge to help me understand my body. I've reached my goal weight but I still follow this way of eating, it's so flexible and enjoyable."
Kristen
UK
Thanks to this style of eating!
"The Med-style way of eating just works so well, as does 16:8 TRE. I am stronger, less anxious and generally happier."
Carolyn
Thailand
So many health benefits!
"My proudest achievement whilst on the plan was finding out that my HbA1c results had gone from 9.8% down to 5.4% over the 12 weeks."
Steven
UK
I'm out of the pre-diabetes range!
“I lost 26 kilos in 24 weeks! Before trying The Fast 800, I had no structure to my meals. Thanks to the programme, following The Very Fast 800 and then The New 5:2, I’ve lost 26kg.”
Tracey
Australia
My mind is so much clearer
"If I can transform my health, anyone can. I didn’t think I would have the willpower but I would tell anyone in my position to be positive, and try it for themselves."
Sandra
UK
It is the best thing I have done in my life
"I wasn't one of the people who lost a lot of weight at the start of The Fast 800. I steadily lost a few pounds each week. By the end of the initial 12 weeks of The Fast 800 I had lost 32 pounds and 7.5 inches off my waist."
Theresa
I am so glad I persisted!
Browse through our most commonly asked questions
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Get started for freeYour first 7 days are free with unrestricted access, and you can cancel anytime. You’ll then be charged £119 / $199 AUD / $149 USD for your 12-week plan.
You will also receive a bonus one month free access to The Fast 800 Life for ongoing support. After that, The Fast 800 Life subscription will renew at £12 / $22 AUD / $15 USD monthly. Remember, you can cancel this subscription at anytime.
Our upgraded Online Programme teaches you the health benefits of a moderately low-carb Mediterranean-style diet, so it becomes a way of eating for life. It is based on the latest science and takes an evidence-based approach to healthy living focusing on nutrition, movement, behavioural change and sustainable lifestyle.
It includes:
Your 12-week plan for weight loss and long term health starts straight away.
When you click “start now”, you’ll be asked to create an account. Once your account is set successfully, please go through the checkout process, which requires you to enter credit card details, to trigger your access to the personalisation quiz and the start of your 7 day free trial.
Your credit card will only be charged if you do not cancel prior to the end of the trial period.
Please note, once you cancel the free trial, you will lose access to your account straight away.
The Fast 800 programme is not recommended for the following:
Please read our medical disclaimer for additional information.
The DIAMOND Study performed by Oxford University and Dr Clare Bailey looked at the feasibility of using an 800 calorie, low-carb, med-style diet as a treatment for people with type 2 diabetes.
After 8 weeks the average weight loss was 9.5kg, sustained over the course of the trial.
Results also included a significant drop in blood sugars, blood pressure and the use of medication.
As the Online Programme is guided, you are unable to pause or restart the course.
You can view content from previous weeks and you also receive a free four week trial of the monthly subscription service at the end of the Online Programme to allow you to catch up on any missed content.
Please be aware that Week 1 starts the Monday following sign-up. The time in between sign-up and Week 1 is called the Prepare period, and is designed to give you time to have a look around the programme, start planning your shopping list and recipes, try a workout or two, and get used to how the programme runs and works.
Please ensure that you are signing up according to how much Prepare time you would like before Week 1 commences – for example, if you would like a full week of Prepare time, please sign-up on a Monday or Tuesday, and if you would like to start Week 1 right away, please sign up on a Saturday or Sunday.
If you have any issues with the start date of your programme, please get in touch via our Contact Us form.
800 is the generally accepted number of calories used to achieve weight loss in scientific studies. Professor Roy Taylor, leading researcher into the reversal of type 2 diabetes, used 800 calories in his test group in the DiRECT Trial.
We have found that 800 calories is high enough to be manageable for most members, but low enough to trigger a range of desirable metabolic changes.
No, you don’t have to give up any of these whilst following the Online Programme although, obviously, we would certainly advise everyone to stop smoking as soon as possible, irrespective of their blood sugars.
Coffee and alcohol are still allowed on the programme although the calories in both of these drinks need to be included in the daily calorie limit (noting that alcohol is highly calorific).
A pint of beer or a large glass of wine contains 180 calories, so really best avoided or kept to a minimum.
The good news is that red wine is included in the Mediterranean-Style diet, so once you finish The Very Fast 800 and The New 5:2, and move onto ‘The Way of Life’ approach you will be able to introduce alcoholic drinks back into your lifestyle (we go over this in more detail in the Online Programme).
Black coffee and tea are fine although you will need to include any milks in your daily calorie count.
Still got questions? Please visit our full FAQ page here or contact us and we’ll get back to you!
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