<ul><li>Developed by Dr. Michael Mosley</li><li>The diet claims to potentially cut the risk type two diabetes, heart disease, and cancer</li><li>There are two stages to this diet. Stage 1 requires the person to undergo a very low-calorie diet (VLCD) of 800 calories per day. Stage 2 then involves the progression of the daily 800 calories from 7 days a week to only twice a week, and the remaining 5 days they will be on the Mediterranean diet.</li></ul>

The Fast 800 Diet 

There are two stages to this diet regimen:<ul><li>Stage 1 - targets the metabolically active abdominal fat. It aims to normalize the liver and pancreas fat and help promoted regular insulin response and blood glucose management.</li><li>Stage 2 - is gradual weight loss that includes intermittent fasting and a change to the Mediterrenean diet.</li></ul>To those who would want to adopt this diet, they should be aware that this is profoundly affect their bodies and side effects such as headaches, tiredness, and constipation may occur. It is also recommended that they take vitamin and mineral supplements.

How The Fast 800 Diet Works

The Fast 800 is a diet that is mainly recommended to those who have an obesity-related complication that would benefit from rapid weight loss. This type of regimen should be followed under the supervision of a healthcare expert.It is NOT recommended for those who are: under the age of 18, the elderly, those who have pre-existing medical conditions and are undergoing medication, those who have an eating disorder, and to anyone participating in endurance exercises.

The Safeness of the Fast 800 Diet

If you've ever considered following a weight loss diet make sure you have all the facts first. Our nutritionist takes a look at the Fast 800 diet.

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Developed by <a dir="ltr" href="https://www.bbc.co.uk/programmes/profiles/2kczjZKp8sGSDxSxKYzxsyr/michael-mosley">Dr Michael Mosley </a> of BBC Two’s Trust Me, I’m a Doctor, the Fast 800 diet claims to potentially cut your risk of type 2 diabetes, heart disease and cancer and, because stage one is a very low-calorie diet (VLCD), possibly <a dir="ltr" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6520897/" rel="noopener noreferrer">reverse type 2 diabetes </a>. The diet is aimed at those wishing to lose weight, especially if they carry excess abdominal fat, as well as those with blood sugar issues, including pre-diabetes and <a dir="ltr" href="https://www.ncbi.nlm.nih.gov/pubmed/31097391" rel="noopener noreferrer">type 2 diabetes </a>. Michael designed the diet based on the research performed by <a dir="ltr" href="https://campus.recap.ncl.ac.uk/Panopto/Pages/Embed.aspx?id=c3bef819-e5f4-4a55-876f-0a23436988ed" rel="noopener noreferrer">Professor Roy Taylor </a>of Newcastle University including the <a dir="ltr" href="https://www.diabetes.org.uk/about_us/news/weight-loss-type-2-diabetes-remission-direct-latest" rel="noopener noreferrer">DiRECT study </a>, funded by Diabetes UK.

The Fast 800 diet brings together the concepts of Michael Mosley’s previous books including the <a dir="ltr" href="https://www.bbcgoodfood.com/howto/guide/what-52-diet" rel="noopener noreferrer">5:2 diet </a>and the <a dir="ltr" href="https://thebloodsugardiet.com/how-it-works/" rel="noopener noreferrer">Blood Sugar Diet </a>and combines them with knowledge gained from recent research relating to <a dir="ltr" href="https://www.cell.com/cell-metabolism/fulltext/S1550-4131(16)30250-9" rel="noopener noreferrer">intermittent fasting </a>and <a dir="ltr" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6520897/" rel="noopener noreferrer">low carb or low calorie diets </a>.

The Fast 800 is structured in stages and starts with a rapid weight loss phase, which lasts for a minimum of two weeks and a maximum of 12. This involves following a daily eating plan that is restricted to 800 calories – either by using a VLCD meal replacement product which supplies 600 calories (normally equivalent to three shakes) combined with 200 calories of vegetables; or you can choose to eat real food (recipe ideas are included in the book), which comprise lean protein sources and vegetables. Those adopting this stage of the plan typically have either a lot of weight to lose, require fast results, have reached a weight loss plateau or have type 2 diabetes. Stage one is designed to switch the body from burning sugar to burning fat by prompting mild <a dir="ltr" href="https://www.medicalnewstoday.com/articles/180858.php" rel="noopener noreferrer">ketosis </a>.

The second stage of the plan involves intermittent fasting, restricting calories to 800 a day for two days of the week, then eating a healthy, lower carb Mediterranean diet for the remaining five days. This stage offers an opportunity to embrace home cooking, reduce processed foods and focus on vegetables, wholegrains, nuts, seeds, legumes, healthy fats and lean protein. The plan recognises that sustaining protein intake is important to maintain muscle mass and support metabolism. The plan also suggests <a dir="ltr" href="https://www.ncbi.nlm.nih.gov/pubmed/31774508" rel="noopener noreferrer">time-restricted eating </a>to enhance the benefits of fasting.

Once you’ve achieved your goal weight, you enter the maintenance phase. This phase is designed to fit personal goals and to work with your lifestyle; you’ll continue with the Mediterranean style of eating, following a low sugar diet with limited amounts of starchy carbs, with a weekly fast day, if needed.

Whether the Fast 800 will be beneficial for you will depend on your circumstances. One of the goals of the Fast 800 is to target metabolically active abdominal fat – this fat puts people at risk of lifestyle diseases, like type 2 diabetes. The first stage of the diet works on the premise that when we eat refined, typically ‘white’ carbohydrates, like white bread, pasta and rice, they are easily broken down in the gut to release sugars which over time leads to fat accumulation and possible insulin resistance. The aim of this stage of the diet is to normalise liver and pancreas fat and promote regular insulin response and blood glucose management.

However, adopters should be aware that this rapid weight loss stage can be intense and may have a significant impact on blood sugar levels, so if you are prescribed diabetic medication or insulin you must discuss the plan with your GP and secure their ongoing support and monitoring for the duration of the plan.

During first stage you may also experience side effects – the most common are headaches, constipation or tiredness. This is typically due to dehydration, so the plan encourages you to increase your intake of calorie free liquids to 2-3 litres per day.

If you choose not to use a meal replacement product during this stage, micronutrient intake may be low and a vitamin and mineral supplement may be needed to support nutrient intake. Meal replacement products, such as shakes, are designed to help stave off hunger so if you do elect to follow the ‘real food’ version of the plan you may also be challenged with hunger pains.

Is the Fast 800 diet effective for weight loss?

VLCD, those supplying 800 calories or less, can lead to rapid weight loss, but may not be suitable or safe for everyone and they are not routinely recommended by the <a dir="ltr" href="https://www.nhs.uk/conditions/obesity/treatment/" rel="noopener noreferrer">NHS </a>. Typically, they are only recommended if you have an obesity-related complication which would benefit from rapid weight loss. The NHS advise that for the majority of us to lose weight in a safe and sustainable way, we should reduce our calorie intake to 1,900 calories for men and 1,400 calories for women.

Dr Mosley claims that by following the rapid weight loss stage of the Fast 800 you may lose as much as 14kg over 8 weeks. This does depend on your start weight, how much you need to lose and assumes you remain motivated and committed throughout this challenging phase. Stage two of the plan offers a more sustainable period from which to progress weight loss at a slower rate.

Is the Fast 800 diet safe to follow in the long term?

The <a dir="ltr" href="https://www.nhs.uk/conditions/obesity/treatment/" rel="noopener noreferrer">NHS suggest </a>that should you choose to follow a VLCD you should do so for no longer than 12 weeks and under the guidance of a suitably qualified healthcare professional. Dr Mosley also cites 12 weeks as the maximum period for the rapid weight loss stage of the Fast 800 and that, thereafter, a low-carb Mediterranean diet is followed.

Restricting calories over a long period of time will limit your intake of nutrients and energy, especially if you follow the ‘real food’ version of the plan. Meal replacement shakes are typically fortified with vitamins and minerals and supply protein and essential fats which may help fulfil your nutrient requirements, however, they are still a tool for short-term use only.

Although there are no reported Fast 800 trials the <a dir="ltr" href="https://www.directclinicaltrial.org.uk/" rel="noopener noreferrer">DiRECT study </a>led by Professor Roy Taylor, which inspired components of the Fast 800 diet, continues to monitor participants. The study reported their second year findings which suggest that intensive weight management has the potential to reduce or delay the complications of type 2 diabetes.

Who shouldn’t follow the Fast 800 diet?

It is advisable to refer to your GP or healthcare professional before starting a new dietary regime especially if you are under 18 years old, elderly, have a pre-existing medical condition, including type 2 diabetes or are on medication. You may need your GP’s support to make changes to your medication and to monitor your blood sugar or blood pressure levels as you progress through the plan. You should also consult your GP if you’re taking warfarin, are on blood pressure tablets, are pregnant, breastfeeding or undergoing fertility treatment.

In addition, <a dir="ltr" href="https://thefast800.com/faqs/#toggle-id-2" rel="noopener noreferrer">The Fast 800 Diet </a>is not recommended for people who are underweight or have an eating disorder, are type 1 diabetics, have had a heart condition or are recovering from surgery. The 800 calories restriction is also not appropriate for anyone participating in endurance exercise.

Please note: if you’re considering attempting any form of diet, please consult your GP first to ensure you can do so without risk to health.

This article was published on 5 December 2019.

Kerry Torrens BSc. (Hons) PgCert MBANT is a Registered Nutritionist with a post graduate diploma in Personalised Nutrition &amp; Nutritional Therapy. She is a member of the British Association for Nutrition and Lifestyle Medicine (BANT) and a member of the Guild of Food Writers. Over the last 15 years she has been a contributing author to a number of nutritional and cookery publications including BBC Good Food .

All health content on bbcgoodfood.com is provided for general information only, and should not be treated as a substitute for the medical advice of your own doctor or any other healthcare professional. If you have any concerns about your general health, you should contact your local healthcare provider. See our website <a dir="ltr" href="http://www.immediate.co.uk/terms-and-conditions" rel="noopener noreferrer">terms and conditions </a> for more information.

What is the Fast 800 diet?

The Fast 800 Diet

How The Fast 800 Diet Works

The Safeness of the Fast 800 Diet

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