The Fast 800 diet is one of the most popular weight loss plans out there, alongside similar diets like the 5:2 diet and intermittent fasting.
According to founder Dr Michael Mosley, those who closely follow the Fast 800 plan could see themselves lose up to 11lb in two weeks by limiting their daily intake to 800 calories a day. It's been praised, alongside the 16:8 diet (opens in new tab), as one of the diets that work fast (opens in new tab). Some people also take on the diet because they find it difficult to lose weight in other ways and have found fasting to be most effective.
Dr Michael Mosley says of his diet plan: "Eating well doesn't just help you lose weight. Good food can boost your immune system (opens in new tab), give you energy and even impact your mood." His book The Fast 800: How to combine rapid weight loss and intermittent fasting for long-term health.
What is the Fast 800 Diet?
The Fast 800 diet involves cutting your calorie intake to 800 a day for the first couple of weeks. You then progress to the 5:2 stage – where you’re only required to eat this number of calories for two days a week, while following a sensible diet on the other five days.
There are two well-know books that dieters follow when on the plan. The first was Michael Moseley's The Fast 800 published in 2018 and the second was The Fast 800 Recipe Book, written by Dr Clare Bailey (opens in new tab) and Justine Pattison (opens in new tab), published in 2019. Both are available on Amazon and they provide insightful information, guidance and recipes, a selection of which you can find further down this page.
The Fast 800 Recipe Book: Low-carb, Mediterranean style recipes for intermittent fasting and long-term health £9.50 | Amazon (opens in new tab)
Following Dr Michael Mosley's No.1 bestselling Fast 800, this fabulous companion cookbook offers a collection of delicious, nutritious recipes to help you incorporate the new 800-calorie programme into your daily life.
The Fast 800 Diet: Stage 1
Involves sticking to 800 calories a day for at least two weeks. This should induce mild ketosis (much like the keto diet (opens in new tab)), which is associated with fat burning. It is the most intensive stage of the diet and should last for about two weeks, however, it's not suited to everybody and if this approach is not for you, you can skip ahead to the second stage, the new 5:2.
The NHS (opens in new tab) advises that if you are following an 800 calorie diet, you need to make sure it is nutritionally complete and that it doesn't last for more than 12 weeks.
The Fast 800 Diet: Stage 2
The new 5:2. When you’re nearing your weight-loss target, eat 800 calories on two days of the week and on the others, follow a Mediterranean diet (opens in new tab), exercising portion control.
During this period of the diet, it's advised you enjoy fewer processed and more home-cooked foods, with plenty of vegetables and fruit as well as whole grains, beans, lentils, extra fibre, lots of nuts and plenty of full-fat dairy and oily fish. Sugar should be reduced or avoided, starchy carbs, like white bread and white pasta, are gone, and 45-60g of good-quality protein should be consumed daily.
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Why is this stage important?
On your two fast days, your body will enter a state of ketosis just as it would if you undertook a rapid weight loss plan. With the new 5:2, you will lose fat and achieve a better response to insulin which will in turn, make it easier for you to keep portion sizes regular during the week.
The new 5:2 also gives those on the plan the chance to experience other fasting benefits, such as apoptosis (clearing out of old or damaged cells), tissue regeneration, reduced risk of cancer, increased metabolic rate and decreased inflammation.
The Fast 800 Diet: Stage 3
You’ve hit your goal, so maintenance is key. Make sure you continue to eat sensible portions of moderately low-carb, Mediterranean style food every day and sticking to a low-sugar diet (opens in new tab).
Dr Mosley says, "The Mediterranean diet is the healthiest diet on the planet. There is this perception that Italian food is predominantly pasta and pizza, but this is not true. It’s actually packed with fruit, vegetables, nuts, olive oil and fish – all of which are good for you and have been proven to help prevent dementia, strokes, cardiovascular disease, heart disease and has even in some cases, been known to reverse type 2 diabetes."
The main components of a Mediterranean diet are:
- Daily consumption of vegetables, fruits, whole grains and healthy fats.
- Weekly intake of fish, poultry, beans and eggs.
- Moderate portions of dairy products.
- Limited intake of red meat.
Fast 800 Diet recipes: Breakfast
Spiced breakfast plums
- Put 4 plums, halved and stoned, in a saucepan. Add 2x 10-12cm orange zest strips and 100ml fresh orange juice, 150ml water and ¼tsp ground cinnamon. Stir gently.
- Bring liquid to a simmer, cover with a lid, reduce the heat to low and cook for 10-15 mins.
- Divide the spiced plums between two bowls, along with 100g full-fat Greek yogurt and 15g toasted flaked almonds. This can be served warm or cold.
NOT FASTING? Add extra toasted flaked almonds.
TOP TIP: This dish works as a dessert too!
233 cals | serves 2
Pear and cinnamon porridge
- Place 30g jumbo oats, ½ pear, cored and chopped, and ¼tsp ground cinnamon into a small non-stick saucepan. Pour in 75ml full-fat milk and 120ml water and cook over a low-medium heat for 5-6 mins, stirring constantly.
- Pour into a deep bowl and scatter with 5g flaked almonds to serve.
NOT FASTING? Increase the portion size
267 cals | serves 1
Poached eggs with mushrooms and spinach
- Third-fill a saucepan with water and bring to a gentle simmer.
- Break 2 medium eggs into a cup, then carefully tip one at a time into pan. Cook over a very low heat, with the water hardly bubbling, for 3 mins, or until the whites are set but the yolks remain runny.
- While poaching the eggs, melt 5g butter in a medium non-stick frying pan over a medium heat and stir-fry 75g small chestnut mushrooms for 2-3 mins.
- Add 50g spinach and toss with the mushrooms until just wilted. Season with a pinch of sea salt and black pepper.
- Serve the mushrooms and spinach on plate. Drain the eggs with a slotted spoon and place on top. Serve with more ground black pepper.
NOT FASTING? Serve on top of a slice of wholegrain toast.
Other options include avocado, ricotta and mushrooms (with or without toast) - delicious!
241 cals | serves 1
Fast 800 Diet recipes: Lunch
Curried chicken and lentil soup
- Heat 1tbsp extra virgin olive oil in a large non-stick saucepan, add 1 onion, peeled and finely chopped, and 1 pepper, deseeded and cut into chunks, and gently fry for 5 mins. Stir in 2tbsp curry powder and cook for a few seconds more, stirring constantly.
- Add 1 x 400g can chopped tomatoes and bring to the boil. Cook for 2 mins, stirring constantly, then crumble over 1 chicken stock cube and add 1 litre water.
- Rinse 50g dried red split lentils and add to the pan. Stir in 225g frozen spinach and bring to simmer. Season well with salt and pepper. Cook 10 mins, stirring often.
- Add 200g cooked chicken pieces and cook for 8-10 mins. You can add extra water if needed.
- Adjust seasoning to taste and serve with lemon wedges for squeezing over.
NOT FASTING? Top with 2tbsp of toasted flaked almonds and 1tbspof full-fat Greek yogurt.
223 cals | serves 4
Edamame and tuna salad
- Tip 200g frozen edamame beans into a heatproof bowl and cover with just-boiled water from a kettle. Stir and leave for 1 min to allow the beans to thaw. Drain and rinse under cold water.
- Place the beans, 2 spring onions, trimmed and thinly sliced, 1 x 110g no-drain tinned tuna and 15g parsley in a bowl and use a fork to flake the tuna. Drizzle 1½tbsp cider vinegar and 3tbsp olive oil over salad, season with salt and pepper and toss together well.
- Just before serving, add 2 large handfuls of rocket and toss lightly.
NOT FASTING? Increase the portion size.
408 cals | serves 2
Asparagus, pea and mint frittata muffins
- Preheat the oven to 200C/fan 180C/Gas 6 and generously oil a deep, six-hole muffin tin. Cut six roughly 10cm square pieces of non-stick baking paper and use to line the tins, leaving the excess paper peeking over the sides.
- Third-fill a large pan with water and bring to the boil. Add 150g asparagus, trimmed and cut into 2-3cm pieces, and cook for 4 mins. Add 100g frozen peas and cook for 1 min more. Drain the vegetables and tip into a large bowl with 4 spring onions, trimmed and thinly sliced, and 3-4tbsp chopped fresh mint.
- Beat 6 large eggs in a separate bowl with a good pinch of salt and pepper.
- Divide the vegetables between six muffin cases and top with 65g feta chunks.
- Pour the egg over the vegetables, then bake in the oven for about 20 mins.
NOT FASTING? Increase the portion size.
154 cals per muffin | serves 6
Fast 800 Diet recipes: Dinner
- Preheat grill to medium-hot setting. For the pizza topping, tip ½ a 400g can of chopped tomatoes into a sieve and shake to remove any excess juice.
- Transfer the tomato pulp to bowl and stir in 1tbsp tomato purée and ½tsp dried oregano. Season with salt and pepper.
- Lightly toast 1 wholemeal pitta bread, place on a board and carefully cut in half horizontally with a bread knife. Separate the two pieces, place on a baking tray, cut side down.
- Spread the pitta halves with tomato sauce and top with 2 roasted red peppers from a jar, drained and sliced, and 2 chestnut mushrooms, very finely sliced. Sprinkle with 35g grated mozzarella, drizzle with 1tbsp olive oil and place under the grill for 4-5 mins.
221 cals | serves 2
Sausages with onion gravy and cauliflower mash
- For the cauliflower mash, half-fill a medium pan with water and bring to the boil. Add 1 medium cauliflower, trimmed and cut into small florets and return to the boil. Cook for 15-20 mins or until soft. Drain, then return to the pan. Add 1tbsp olive oil, a couple of pinches of salt and lots of ground black pepper. Blitz in a food processor until smooth. Keep warm over a very low heat, stirring occasionally.
- Meanwhile, heat 2tbsp olive oil in a large non-stick frying pan and gently fry 12 chipolata sausages for 5 mins, turning regularly. Add 1 onion, peeled and thinly sliced, and cook for a further 8-10 mins.
- Stir in 300ml hot chicken or pork stock and 2tbsp reduced-sugar tomato ketchup and bring to simmer. Mix 2tsp cornflour with 1tbsp cold water in a small bowl and stir into the pan. Season with pepper and simmer for 1-2 mins. Adjust the seasoning to taste.
- Divide the cauliflower mash between four warmed plates and top with the sausages and gravy.
NOT FASTING? Increase the portion size and add a generous knob of butter or grated Cheddar to the cauliflower after blending, and mix thoroughly.
367 cals | serves 4
Spicy bean chilli
- Heat 2tbsp oil in a large, deep, non-stick frying pan, and gently fry 1 peeled and sliced onion for 3-4 mins.
- Add 1tsp smoked paprika, 1tsp cumin and 1tsp ground coriander and cook for a few seconds, stirring well.
- Add 1 x 400g can of chopped tomatoes, 1 x 400g can of drained black beans and 1 x 400g can of drained mixed beans, 250ml vegetable stock, 1tbsp tomato purée and 1tsp mixed dried herbs, season with salt and pepper and bring to simmer. Cover loosely with lid and cook for 15-20 mins, stirring occasionally.
- Serve topped with a sprinkling of Cheddar (75g in total) and generous spoonfuls of full-fat Greek yogurt.
NOT FASTING? Serve with cooked brown rice and top with sliced avocado.
346 cals | serves 4
Fast 800 Diet: Snack recipe
Almond and raisin chocolate pennies
- Line a baking tray with non-stick baking paper.
- Break 100g plain dark chocolate into squares and place in a bowl over a pan of gently simmering water. Make sure the base of the bowl isn’t touching the water. Leave to melt for 5 mins, stirring occasionally. Or, melt in a microwave on high for 1-2 mins.
- Carefully remove the hot bowl from the pan and, using a teaspoon, pour individual spoonfuls of melted chocolate onto the tray, spaced well apart.
- Scatter 25g flaked almonds and 25g raisins on top of the melted chocolate. Leave to set for 2-3 hours.
- Place in an airtight container and store for up to a week in a cool place.
38 cals per penny | makes 20
The Plan is a calorie-controlled diet. Individual results will vary. If you are adolescent, pregnant, breastfeeding, have a medical condition, or are unsure in any way then talk about your weight-loss plans with your doctor or dietician.
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