Dr Michael Mosley, the man who launched the 5:2 diet revolution, has refined and revised his original plan – followed by Hollywood stars and politicians as well as millions of Britons – with the help of the latest scientific research
THE 5:2 DIET, FIVE YEARS ON
This year’s Oscars ceremony will be remembered chiefly because the producers of La La Land were mistakenly told they had won Best Picture and then had to hand the award back. I, however, was far more interested in the appearance of the host, comedian Jimmy Kimmel, than anything else that was going on. Jimmy is a big fan of the 5:2 diet, which he credits with helping him lose 30lb and keep it off. ‘It has helped me stay at 182lb,’ he said in a recent interview, ‘and made me appreciate the food that I eat.’ (I am happy to report that as well as looking slim and healthy, Jimmy was also very funny.)
The 5:2 diet has changed my life, but it came about largely by chance. Five years ago I discovered that, like my father, I had become a type 2 diabetic. My father died at the relatively early age of 74 from complications of diabetes and I was desperate not to follow in his footsteps. So rather than start on medication I looked for alternative ways to improve my blood-sugar levels and came across something called intermittent fasting. This led to my making a documentary, Eat, Fast and Live Longer, and writing a book, The Fast Diet, with journalist Mimi Spencer, which became an international bestseller.
THE KEY: FASTING
‘Intermittent fasting’ is not fasting in the sense that you are going entirely without food. You are simply cutting back on your calories a few days a week. There are many different approaches, from alternate day fasting to the 16:8 diet, but the 5:2 (reducing your calories to around 600 a day, twice a week) is the one that many people find easiest to do.
On the 5:2 I lost 9 kilos and reversed my diabetes. The TV presenter Phillip Schofield told me that it has become a way of life for him. I’ve read in the press that it has been embraced by celebrities such as Beyoncé, Benedict Cumberbatch (‘you have to, for Sherlock’), Liv Tyler, Ben Affleck and Christie Turlington. I have also had messages of thanks from thousands of people, ranging from, ‘I lost 40lb and a year later the weight is still gone’ to ‘I can now take my jeans off without undoing them and I am happy to do so if anyone wants to watch!’
When I wrote The Fast Diet back in 2012 there was already compelling evidence of the health benefits of intermittent fasting. Since then there have been many more studies showing that it can not only lead to significant weight loss but also trigger changes within the body that reduce your risk of a range of diseases. A recent review article, published in the science journal Cell Metabolism, concluded that intermittent fasting ‘helps reduce obesity, hypertension, asthma and rheumatoid arthritis. It has the potential to delay ageing and help prevent and treat diseases.’
SO HOW DOES IT WORK?
Many people find cutting their calories a couple of days a week more doable than being on a constant diet. A study carried out in Manchester, which involved more than 100 women, found that those on the 5:2 lost nearly twice as much fat as those allocated a standard diet. They were also far more likely to stick to it.
Intermittent fasting also switches on repair genes, whose job it is to keep your body in good shape.
We tend to treat our bodies like a car: we keep it topped up with high-calorie fuel and drive it hard. If you do that it will, eventually, break down. It’s only when you go for long periods without food (around 12 hours) that your body switches to ‘clean up and repair’ mode.
Going on a short fast is a bit like taking your body along to the garage. Freed from their normal routine work, the little gene mechanics start doing urgent maintenance tasks. Part of that involves something called autophagy. Autophagy, meaning ‘self-eat’, is a natural process during which the body breaks down and recycles old and tired cells. Just as with a car, it is important to get rid of damaged or ageing parts if you want to keep things in good working order.
Fasting not only helps clear out damaged old cells but can also spark the production of new ones. In a fascinating study published a couple of weeks ago, Professor Valter Longo of the University of Southern California showed that in mice, if he cut down their calories for a few days a month, he could regenerate parts of their pancreas.
Your pancreas produces the hormone insulin, which brings down your blood-sugar levels when they get too high. In diabetics the insulin-producing cells in the pancreas are damaged and they no longer work properly, which means diabetics often end up having insulin injections. It is extremely exciting to see that fasting could reverse this damage.
Professor Longo has also shown that intermittent fasting can boost the immune system. If you do a short fast and then eat, you get a rebound effect, with the creation of new, more active white cells. ‘We could not have predicted,’ he told me, ‘that fasting would have such remarkable effects.’
Harissa chicken salad
OTHER METHODS OF INTERMITTENT FASTING
There are a number of other options, including alternate day and the so-called 16:8 diet. The latter has been popularised by X-Men actor Hugh Jackman, who credits it with helping him develop his impressive physique.
To do a 16:8 diet you cram all your calories into an eight-hour window and then fast for 16 hours. There have been a number of rat studies that have shown that this can be beneficial, but so far the only lengthy human study that I know of was carried out for a television series I present, Trust Me, I’m a Doctor.
For this study we teamed up with Dr Jon Johnston of the University of Surrey. We recruited 16 volunteers and randomly allocated them into two groups. One group continued as normal. The other was asked to eat the same amount of food as normal, but to eat their breakfast 90 minutes later than usual and have their evening meal 90 minutes earlier. They were not allowed to snack in between, which meant they were going three hours longer each night without food.
After ten weeks we found that, compared to the control group, the group who had restricted their mealtimes showed significant improvements in their cholesterol and blood-sugar levels. They also lost more body fat. Sticking to a regime like this can be tough, but this study does suggest that delaying breakfast or eating dinner a bit earlier brings benefits.
AND NOW IT’S EVEN MORE DOABLE THAN BEFORE
I have learnt a lot about the science of weight loss since I developed the 5:2 diet, some of which you’ll find in my book The 8-Week Blood Sugar Diet. Here are my ten essential tips
1 First the good news. You don’t need to stick to 600 calories on fast days. Cutting down to 800 calories seems to be almost as effective and for some people much more doable.
2 If you want to do a Really Fast Diet then you should eat 800 calories a day for a couple of weeks, before switching to 5:2. Studies have shown that if you do this you can expect to lose several kilos a week and most people say they soon stop feeling hungry. Contrary to what you have been told (and I used to believe), rapid weight loss can be a more effective way to achieve your goals, both in the short and the long term. You must, however, ensure that you are getting the right balance of protein and other nutrients.
3 You will get much more benefit out of intermittent fasting if you switch to a low-carbohydrate Mediterranean-style diet, both on the days when you are fasting and when you are not. That means more olive oil and nuts, as well as plenty of eggs, yoghurt, oily fish and vegetables.
4 It’s important that you increase your physical activity if you want to keep the weight off. This means doing muscle-building exercises, such as press-ups and squats, as well as aerobic exercise such as cycling or speed walking. You should also try to get your pulse racing a couple of times a day (perhaps by running up the stairs) and take every opportunity you can to move more.
5 Drink plenty of fluid. A hot drink on an empty stomach is remarkably soothing. If you don’t drink enough then you may well develop headaches and constipation when fasting. How much is ‘enough’? The magic figure that is often quoted is two litres or eight cups a day. Tea and coffee count.
6 But do keep an eye on the amount of calories that you are drinking. Smoothies have a reputation for being healthy but by the time you get rid of the fibre you are left with a lot of calories (well over 200 in a small bottle) as well as a big sugar hit. In a recent survey researchers discovered that out of 52 commercial smoothies, 41 had more sugar than Coca-Cola and all had more calories.
7 and watch the alcohol. It is another way of consuming calories without noticing. A large (175ml) glass of red wine contains about 120 calories, while a pint of Guinness clocks in at around 170. You don’t need to give up entirely, but a couple of days a week without is good for your health as well as your waist.
8 Empty all the junk food out of your house. Getting rid of temptation means you are far less likely to cheat on fast days, and you are also less likely to indulge in mindless eating on other days. Unfortunately willpower is grossly overrated and if you know the treats are close at hand you will almost certainly eat them. A particularly difficult moment is at the end of the day when you are relaxing. If you sit down in front of the television with a packet of crisps or biscuits anywhere nearby, you will probably scoff them without noticing.
9 However, be wary of being in a constant state of self-denial. It is fatal to declare too many foods off limits, as this often leads to guilty, rebound overeating. I try to limit my consumption of chocolate by buying small amounts and walking to the shops, which are a mile away, when the craving is strong. I nibble on foods such as cheese or nuts and buy snacks such as unsalted almonds or walnuts because I know I can stop after a small handful. If I buy salted peanuts I will eat the whole pack.
10 Make sure you fill up on protein and vegetables on your fasting days. Protein is very satiating and you can eat a lot of vegetables for very few calories. There are lots of recipes in The 8 Week Blood Sugar Diet Recipe Book and my website, thebloodsugardiet.com, has a friendly forum where people offer help and support.
Thai prawn cakes with Asian coleslaw and soy dip
ESSENTIAL 5:2 KNOW-HOW
The basics in a box
‘The 5:2 approach is very simple. FOR five days a week you don’t calorie count. Then for two days a week you cut down your calories,’ explains Dr Michael Mosley,in The 8-Week Blood Sugar Diet. ‘You can do this on any two days of the week that suit you, but it is best to be consistent so you get into a pattern. Try consecutive days or you may prefer to split them – whatever works for you. In the original version of the Fast Diet, I recommended men to stick to 600 calories and women to 500, twice a week. Going up to 800 calories isn’t going to make that much of a difference, particularly if you go low carb on the other five days.’ Dr Mosley suggests adopting a low-carbohydrate Mediterranean-style diet, low in the starchy carbs but packed full of disease-fighting nutrients, healthy fats, fish and quality proteins and plants.
MEDITERRANEANISE YOUR EATING
♥ Eat plenty of different coloured veg and avoid too many sweet fruits.
♥ Cut right down on sugar and sugary treats and minimise refined, starchy white carbs.
♥ Switch instead to quinoa, bulgur (cracked wheat), whole rye, whole-grain barley, wild rice and buckwheat. Brown rice is OK.
♥ Legumes such as lentils and kidney beans are healthy and filling.
♥ Focus on high-quality protein, including oily fish, prawns, chicken, turkey, pork, beef and eggs (and vegetable sources including soya, edamame beans, Quorn and hummus)
♥ Eat more healthy fats and oils. As well as oily fish (salmon, tuna, mackerel), include more olive oil on salads and veg. Use olive, rapeseed or coconut oil for cooking.
♥ Avoid margarine and use butter instead. Full-fat yoghurt is good and cheese in moderation is fine.
♥ Read more on Mediterranean eating in The 8-Week Blood Sugar Diet.
Raspberry cheesecake bars
HEALTH ADVISORY: READ THIS
As with any weight-loss plan, always see your doctor before embarking. Seek medical advice if you:
- have a history of eating disorders
- are taking prescribed medication
- have a significant medical or mental health condition
- are pregnant or breastfeeding.
Don’t go on the diet if you:
- are under 18
- are very lean or underweight (BMI below 21)
- are recovering from surgery or generally frail.
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