What is The Fast 800 diet?

How does The Fast 800 diet work?

The Mediterranean diet and intermittent fasting are two eating strategies that have received a lot of attention and praise in recent years. The Fast 800 diet combines these in one flexible, low-calorie eating plan that tackles weight loss in three dietary stages - to help you get it off and then keep it off.

Developed by Dr Michael Mosley in 2018, the diet claims to help people lose excess weight and reduce the associated health risks, including heart disease and type 2 diabetes. As stage one is a very low-calorie diet (VLCD), Fast 800 may also help people with existing type 2 diabetes reverse their condition.

According to its founder, The Fast 800 diet is more than an 800-calorie-a-day restrictive diet. It incorporates healthy Mediterranean-style food, fasting days, regular exercise, and mindfulness activities.

What can I eat on The Fast 800 diet?

There's no rigid meal plan on Fast 800, but what you eat should follow the principles of a moderately low-carb Mediterranean diet. This involves lots of fruits, vegetables, nuts, and seeds, as well as healthy fats, like those found in olive oil and fish, and fibre-rich carbs, like those found in whole wheat foods and beans. There's plenty of research showing how effective this diet is at significantly lowering obesity and weight-related health problems¹, and many of the healthiest and longest living people in the world eat this way.

What is intermittent fasting?

Intermittent fasting involves time-restricted eating - having at least a 12-hour break in between meals - and calorie-restriction in the period when you do eat. In the case of The Fast 800 diet, your calories are restricted to 800 during your eating window. By fasting for at least 12 hours during each 24-hour period, you can trigger your body to burn more energy. There's also mounting evidence that this may also help protect against conditions like diabetes, cardiovascular disease, and glucose intolerance².

What are the other lifestyle changes on Fast 800?

While you may see a difference by changing your eating habits with The Fast 800 diet, for the best and most sustainable results, founder Dr Mosley encourages combining dietary changes with exercise and mindfulness. Specifically, switching between regular resistance exercise sessions and high-intensity interval training (HIIT) is an effective way to maintain healthy weight loss. Practising mindfulness may not burn calories, but it can help keep you motivated, improve your sleep, and teach self-compassion and relaxation³ - useful tools to help you stick with Fast 800.

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Does The Fast 800 diet work?

We've looked at how eating Mediterranean style, intermittent fasting, exercise, and mindfulness are each associated with healthy weight and a reduced chance of certain diseases. Dr Mosley believes that the 800-calorie rule is the most effective way to help you get there if you have a lot of weight to lose.

This is based on several studies, including the DiRECT trial - a major study that found an 800 calorie-a-day diet can lead to major weight loss and reverse type 2 diabetes⁴:

• 24% of participants lost more than 15kg in 12 months.

• 46% of participants reversed their diabetes in 3 - 5 months.

However, neither the NHS nor The Fast 800 diet recommends following this restrictive stage - The Very Fast 800 - for longer than 3 months (12 weeks) due to safety concerns. But this is enough time to see significant improvements in weight, related diseases, and other health markers that come with cutting down on processed foods, refined sugars, and unhealthy fats - for example, improved moods, better sleep, and more energy.

Is The Fast 800 diet safe?

The New 5:2 and Way of Life are generally considered safe for most people, with no time limits in place for how long you can follow these approaches. However, The Very Fast 800 isn't right for everyone, and those who can undertake it must do so for a maximum of 12 weeks.

Here's why:

1. Very low-calorie diets (VLCDs) are typically only recommended for people with obesity-related health risks, where losing weight quickly could significantly benefit their health. For most other people, eating up to 1,900 calories for men and 1,400 calories for women should result in healthy weight loss⁵.

2. VLCDs may affect blood sugar levels, so if you're prescribed insulin or diabetic medication you must discuss this diet plan with your doctor.

3. With VLCDs you are getting much less energy than before. This can lead to side effects like tiredness and brain fog. You also need to ensure you're staying hydrated with 2-3 litres of calorie-free drinks a day - preferably water - to avoid dehydration, associated headaches and constipation, or its more serious side effects.

4. While it's possible to get the short-term nutrition you need with VLCDs, it's much easier to miss out on essential vitamins and minerals. Sticking to the Mediterranean diet is important, and your doctor can also suggest food supplements to support you during this time.

Can I try The Very Fast 800 diet stage?

Check with your doctor if:

• You're under 18 years old.

• You're over 65 years old.

• You're pregnant, breastfeeding, or undergoing fertility treatment.

• You have a pre-existing medical condition, including type 2 diabetes.

• You're on medication, including warfarin and blood pressure tablets.

The Fast 800 diet recipes

Vegans note - there are no dedicated vegan fasting meal plans on The Fast 800 diet online plan. It's possible to adapt the Way of Life stage for a plant-based diet, but you'll need to make sure you're consuming enough protein.

Sample breakfast Fast 800 diet recipes:

• Omnivores/vegetarians: Try the green brekkie bowl.

• Omnivores/vegetarians: Try these banana pancakes.

Sample lunch Fast 800 diet recipes:

• Omnivores: Prepare this Mediterranean tuna salad.

• Vegetarians: Cook a Mediterranean omelette.

• Vegans: Make a chickpea soup with greens.

Sample dinner Fast 800 diet recipes:

• Omnivores: Slow cook this lamb stew.

• Vegetarians: Try a vegetarian chilli.

• Vegans: Cook a low calorie thoran.

Sample treats Fast 800 diet recipes:

• Ominvores/vegetarians: Indulge in choc berry bites.

• Ominvores/vegetarians: Enjoy a plum crumble.

Further reading

1. Finicelli et al: The Mediterranean diet: an update of the clinical trials.

2. Yuan et al: Effect of intermittent fasting diet on glucose and lipid metabolism and insulin resistance in patients with impaired glucose and lipid metabolism.

3. Janssen et al: Effects of mindfulness-based stress reduction on employees' mental health: A systematic review.

4. Lean et al: Durability of a primary care-led weight-management intervention for remission of type 2 diabetes: 2-year results of the DiRECT open-label, cluster-randomised trial.

5. NHS Better Health: Calorie counting.