How To Do The Fast 800 Keto Diet

26th January 2022

How To Do The Fast 800 Keto Diet

The Fast 800 Keto is different from your typical high fat, low carb ketogenic diet. The Fast 800 Keto builds on the science that provides the foundation for The Very Fast 800 and simply reduces the carbohydrates even further to push your body into more consistent nutritional ketosis.

What is ketosis?

Ketosis, in basic terms, is the metabolic state that occurs when your body doesn’t have enough glucose from carbohydrates to burn for energy. When this happens, your body seeks energy in the form of glycogen (glucose stored in your muscles and liver). When glycogen stores run low, around 10-12 hours after eating, your body turns to fat as an energy source. Fat is converted into ketone bodies, which your body will then use for energy.

You can achieve ketosis through reducing your carbohydrate intake (nutritional ketosis) or through incorporating intermittent fasting/Time-Restricted Eating (fasting ketosis). Here at The Fast 800, we offer options for both, depending on what’s achievable for you.

What foods to eat on The Fast 800 Keto Diet

If you’ve read Dr Mosley’s latest book, The Fast 800 Keto, you’ll know that he recommends following the rule of 50:50. Keeping carbohydrates under 50g per day and ensuring protein remains above 50g.

For the Online Programme, we have now developed keto meal plans, where calories fall between 800-1000 each day. The meal plans have been carefully designed to ensure you consume at least 50-60g of protein and around 20g or less carbohydrates. Our carbohydrates are significantly lower than Dr Mosley’s recommendations to allow you to add extra low-calorie, non-starchy vegetables to every meal, without having to worry about counting extra carbs.

If you’re looking for options with slightly higher carbohydrates and a greater focus on calorie restriction then The Very Fast 800 meal plans may be a better choice; The Very Fast 800 and plans including fasting days are similar to this, however, you have slightly more carbohydrates at around 50g or less per day (still considered low-carb) and the rest is healthy fats.

Alternatively, if you’re not looking to lose weight rapidly, and are looking for more gradual, and sustainable weight loss with improved metabolic health, The New 5:2 or Way of Life approaches are fantastic options.

What does The Fast 800 Keto Diet Plan Look Like

What does science say?

Keto diets have been around for hundreds of years. Originally created to help those with epilepsy by reducing the brain’s need for glucose as fuel, therefore slowing the misfiring that causes seizures.

Research in recent years has found the keto diet to be effective for those with type 2 diabetes to help reduce central obesity, manage their blood sugar levels and potentially reverse the condition. While the participants in these trials struggled to maintain a ketogenic diet long-term, the short-term application for rapid weight reduction, improved blood sugars and other metabolic markers is promising. 

The Fast 800 Keto plans are a Mediterranean version of keto, lower in saturated fats, with plenty of green vegetables, olive oil, nuts, oily fish, and protein. From numerous studies, we continue to advocate a Mediterranean-style diet for being the most effective for short, medium and long-term health and wellbeing. 

Other benefits of a keto diet

  • We know that if you have high blood sugars, a keto diet is likely to bring them down.
  • Reducing your carbohydrate intake helps to suppress hunger, making it easier to stick to a low calorie diet. 
  • A low calorie keto diet is an effective way to lose weight and maintain muscle mass, good for preserving your metabolic rate. 
  • Research has recognised that a keto diet may help people to lose 3 times more visceral fat than those on just calorie restriction.

In December 2021, Dr Mosley completed 7 days of The Fast 800 Keto, here are his results: 


“In just 7 days I’ve lost 2.2kgs, 2cms around my waist, my blood pressure has gone down by 10 points into the super healthy range and my early morning fasting blood sugars have dropped from 5.6 (borderline prediabetic) to 4.6 (super healthy). All in seven days!”

– Dr Michael Mosley

There is compelling evidence that when you use a keto meal plan, you go into ketosis faster, and begin to burn more fat. However, it can be difficult with such restriction, which is why it’s not for everyone. The Fast 800 Keto reinforces everything that we believe at The Fast 800 and does not undermine the science behind The Very Fast 800. The Fast 800 Keto may not be for everyone but is something you may wish to explore. 


Who is The Fast 800 Keto for?

Our brand new keto plans have been developed for those who have a lot of weight to lose, and are ready and committed to make changes. People who are pre-diabetic or have type 2 diabetes could follow these plans (monitored by a GP) to improve their insulin sensitivity. A rapid weight loss plan, with typical weight loss of around 10kg in 12 weeks, is a proven way to reverse, and prevent the onset of, type 2 diabetes.

The Fast 800 Keto plans are not replacing The Very Fast 800 plans, they are simply an option for those that are looking for a little more and who are motivated to follow a very restrictive meal plan. If you decide you do not like this approach or would prefer more variety, you can switch to The Very Fast 800, or our other plans, at any time when you join the programme.

How long can the The Fast 800 keto plans be followed for?

We recommend that you follow The Fast 800 Keto plans for no more than 12 weeks. When you have completed this or attained a healthy BMI, move to The New 5:2 or Way of Life. We’re encouraging our current members to think of The Fast 800 Keto and The Very Fast 800 as interchangeable; you cannot complete 12 weeks on one, then 12 weeks on the other. It’s either/or, whichever works best for you. 

If you have previously followed 12 weeks of a calorie restricted diet (like The Very Fast 800) and have found that you have put on unwanted weight over a period of time, you can follow the keto plans for two weeks to kick start weight loss, before moving on to The New 5:2 for long-term results. 

Are there any products to support a keto diet?

Absolutely! We understand that it can often be difficult to achieve more than 60g of protein through diet alone, particularly when following a low calorie diet, and have created keto-friendly protein powders to make things a little easier. Unlike fats and carbohydrates, your body cannot store protein, which is why keeping up a good daily intake is so important to support metabolic health. 

Our new protein is currently available in the UK and suitable for vegetarians and vegans. You can find out more about it here

Do the new keto plans replace The Very Fast 800 plans?

No, the keto plans are simply an option for those feeling a little more ambitious and looking for accelerated weight loss.

The Very Fast 800 is still a valid approach, and more suitable for those new to low calorie diets, that will definitely kickstart your weight loss journey – it will most likely put you into a state of mild ketosis because you will be running down your sugar supply. You may find your body comes in and out of ketosis while following The Very Fast 800; being able to switch back and forth from using glucose and ketones as energy is a great skill to teach your body and helps it to become metabolically efficient. Due to the calorie restriction, you will still be losing weight. 

Essentially, The Fast 800 Keto is an accelerated method of falling into nutritional ketosis and keeping you there. If you’re looking to try out new keto meal plans, you can do so today by signing up to our 7 day free trial.

References arrow down

Mosley, Michael, The Fast 800 Keto, 2021. Short Books.

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