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What really happens when you try the Michael Mosley Fast 800 diet for a week
The doctor credited with creating the 5:2 diet introduced to the world in his 2012 documentary Eat, Fast and Live Longer has updated the plan. Dr Michael Mosley’s original diet works on the idea that five out of seven days are routine food days and on the remaining two days calories are restricted to around 500-600 per day.
Now, in an updated version of the fasting diet, Fast 800, Mosley has come up with a plan that sees users eat 800 calories a day – the Fast800.
Michael Mosley’s Fast800 is a diet and lifestyle approach based on the principles of intermittent fasting and calorie restriction to promote weight loss and improve overall health. The Fast800 diet encourages participants to consume a reduced calorie intake of around 800 calories per day for a specific period, usually eight weeks. During this period, individuals follow a Mediterranean-style eating plan that focuses on whole foods, such as vegetables, fruits, lean proteins, and healthy fats.
Intermittent fasting is a key component of the Fast800 approach. It involves restricting the time window in which one consumes food. One common method is the 16:8 pattern, where an individual fasts for 16 hours and has an eating window of 8 hours. This pattern can be adjusted to fit individual preferences and schedules.
The Fast800 program also emphasizes regular physical activity, such as brisk walking and strength training, as well as stress management and getting adequate sleep.
The overall goal of the Fast800 approach is to help individuals lose weight, improve insulin sensitivity, lower inflammation, and promote better overall health. It combines aspects of calorie restriction, intermittent fasting, and healthy eating to achieve these outcomes.
WalesOnline journalist Lydia Stephens decided to try the plan for a week – and see what happened. She said: “Like many people, I gained a lot of weight over lockdown, and I have struggled with it since. By January 2023, my BMI was borderline obese.
“I felt awful. I had limited energy to do anything outside of work. I did no exercise at all and if I tried to go for a walk I would be quickly out of breath. It was a wake-up call to make a change. Fast forward to May and I have lost just over 20lbs. My BMI is now just slightly into the “overweight” category but I’ve struggled to do anything but make slow progress. So I thought I’d give the Fast 800 a go.
“When signing up for the plan, I was asked several questions about my height, weight and waist measurements. There are several diet plans available, and I was recommended the Fast 800 plan. I chose to eat two meals a day, making up to 800 calories.
“Once I was signed up, a seven-day plan was made up for me with two meals a day, recipe and ingredients list included. The plan provided me with a printable shopping list. Seven days worth of meals came to £49.15 (at Aldi.) This was for two (small) portions of the meals.”
Lydia has set out a diary of what happened during her seven days on the plan…
Monday
What I ate : Cheesy scrambled eggs with pesto, one cup of tea and one cup of coffee, and spinach and turkey mince Bolognese with courgette.
I really enjoyed the pesto scrambled egg (Image: Lydia Stephens)
The turkey Bolognese was a hit (Image: Lydia Stephens)
I started the day with a small coffee with a dash of full fat milk at about 10.20am. The first meal was tasty cheesy scrambled eggs. I added spinach which wasn’t part of the recipe but the plan allows you to add non-starchy vegetables to your meal. I had a cup of tea at 2pm before dinner at 5.40pm. It was turkey mince Bolognese with courgette instead of spaghetti and added parmesan. I wasn’t looking forward to this at all. I thought the courgette would be horrible on its own like that, but it was surprisingly really tasty. I did fancy something sweet afterwards but didn’t cave.
Tuesday
What I ate: Apple, a handful of strawberries, Mediterranean omelette and teriyaki salmon with courgette, one cup of tea and one cup of coffee.
The omelette ended up being more like scrambled egg (Image: Lydia Stephens)
The salmon with teriyaki sauce (Image: Lydia Stephens)
I had an apple for a snack around 10am and by 12.30pm I had a strong headache and felt really hungry. The first meal was an omelette, but without any cheese. It was made up of red pepper, mushrooms, two eggs and some cannellini beans. It was bland but a quick and easy meal to have for lunch. Dinner was teriyaki salmon and courgette at 6pm. This was super easy and quick. Not that tasty or satisfying though, and I did go looking for a chocolate at around 9pm but had none in the house so managed to stay on plan.
Wednesday
What I ate: Salmon, courgette, apple, mince beef salad with lettuce tomatoes and cheese, one cup of tea and one cup of coffee.
The beef taco salad (Image: Lydia Stephens)
By 8.30am on Wednesday morning I was really hungry. I really wanted a bowl of cereal (a bit of a trigger food for me), but the scales are telling me I’m already a couple of pounds down in just two days and it was a motivating factor to stay on track. I had a coffee to tie me over until lunch.
Lunch was leftover salmon and courgette from the night before, which I had at around 11.30am. I then had an apple around 12pm as I wasn’t feeling that satisfied. Dinner at 5pm was supposed to be mince beef tacos in lettuce with tomato and cheese. I couldn’t get the lettuce to work as tacos so I just had what looked like a beef burger salad instead. The mince was super quick and easy to cook but was a very small portion. I didn’t feel that satisfied afterward and ended up eating two Oreo biscuits later.
Thursday
What I ate: Two boiled eggs with feta cheese, peppers and avocado, mince beef salad with lettuce tomatoes and cheese, raspberries, strawberries, a cup of coffee and a tea.
I loved the Mediterranean salad (Image: Lydia Stephens)
I was hungry by 8am, but once again used a coffee to curb my hunger. I had my first meal of two boiled eggs, feta cheese, peppers and avocado at 11am. This was really tasty and surprisingly satisfying.
I had a couple of berries around 4pm to tie me over until dinner at just after 5pm. I changed up my plan for my evening meal because I was in the office and knew I wouldn’t want to cook by the time I got home. So I had the leftovers from Wednesday’s beef burger style salad. I enjoyed it a lot more this time around. I ate that just after 5pm and that was it for the day.
Friday
What I ate : Two scrambled eggs with pesto and feta cheese with spinach, bowl of granola, bar of Oreo Dairy Milk, cup of coffee and cup of tea.
Things went a little wrong on Friday (Image: Lydia Stephens)
The day it all went wrong. Because I changed my meal around, what had been the plan for Thursday’s evening meal should have been Friday’s first meal. So I improvised and recreated a dish from earlier this week, but used feta instead of cheddar. I had this around 10.30am, and by 11am I was still so hungry. I don’t work Fridays so I found it hard to not think about that hunger and opt for something that was allowed on the plan (like berries or an apple). I caved and I had a very small bowl of granola at around 11am.
I also didn’t stick to the evening meal, I was out all afternoon and starving by 4pm and had to go to a local shop to drop some parcels off. The chocolate was too tempting and I had a bar of Oreo Dairy Milk. I’m not going to look at the amount of calories that was in the bar because, in the grand scheme of things, I had eaten pretty much perfect to plan all week and I don’t want to torture myself for having one treat.
Saturday
What I ate: Cup of coffee, banana pancakes, apple, beef stir fry with peppers, mushrooms, broccoli and pak choi, small piece of cake, cup of tea.
It made six pancakes (Image: Lydia Stephens)
The beef stir fry was tasty and satisfying (Image: Lydia Stephens)
I started the day with a cup of coffee. The first meal of the day at 11am was super-easy pancakes made with two eggs and one banana. I have made them like this before so knew what to expect. They were OK, not delicious, but did fill me up. I would have added berries and Greek yoghurt but had none left. I had an apple around 3pm.
I had dinner at around 6pm. It was a really nice beef stir fry, probably the most filling meal of the week with the amount of veggies I loaded in. My partner had brought home cakes from work so I had a taste of one of those too, not really because I was hungry, more so because it was too hard to resist.
Lydia said: “The diet does exactly what it promises: I lost weight fast. After just three days I was 3lb down, and after just six days I was 5lb down. I really was not expecting that much of a loss. I’ve never lost more than 3lb across seven days before, so I am really impressed that it works.
“Apart from the chocolate bar on Friday and cake Saturday, I felt like I could really stick to the plan as I knew what I was having for lunch and dinner each day. I knew it was in the fridge ready to cook, and all the recipes were really easy and fuss free. This meant I could cook dinner and eat it within 15 minutes of finishing work, which is always the time I go looking for sugary snacks.
“I won’t pretend that it wasn’t hard, and I have followed intermittent fasting hours loosely for the last few months, so this isn’t the first time I’ve gone so long without food. But, I was always really hungry every morning, and in the evening a few hours after my dinner. I definitely would find it a lot harder if I wasn’t following this while working and had more free time to look for snacks.
“The plan does suggest you would lose appetite for sugary snacks, which I haven’t, but it might just be I’ve not followed it for long enough. I’m going to follow the Fast 800 for another week before swapping to the 5:2, as I really think this has helped kick start my weight loss again after struggling at the same sport for the last several weeks. I feel like I’ve hit the reset button.”
Michael Mosley is a British television presenter, journalist, and physician best known for presenting and co-producing a number of science and health-related documentaries for the BBC. He is particularly known for his investigations into the human body and various aspects of health and well-being.
Some of Mosley’s notable works include “Inside the Human Body,” a documentary series that explores the inner workings of the human body, and “The Truth About…” series, where he investigates various health topics such as food, exercise, and sleep. He has also written several books on health and lifestyle, including “The Fast Diet” and “The Clever Guts Diet,” which promote methods for improving health and well-being.
Michael Mosley’s work often focuses on combining scientific research with practical advice to help people understand and improve their health. He has become a popular figure in the field of health and wellness due to his engaging presentation style and his ability to communicate complex scientific concepts in a clear and accessible manner.
