This is the new 'fad' diet that's helped millions lose weight easily and quickly...

When the sun is shining and the days are long, you feel naturally motivated to head outdoors and get active!

But come the cold, harsh months of winter, eating clean and slimming down can seem a whole lot more challenging.

Too much fat, particularly around the gut, is not only unsightly but it is also extremely unhealthy.

Dr Michael Mosley used what he's learned about dieting over the last decade to create a three-in-one approach that can be used if you just want to lose an inch around the middle, have a stone or more to shift, or need to shed a more drastic amount, reports Daily Mail.

Dr Mosley's 5:2 diet has helped countless people slim down.

After 12 weeks on the plan, you could see more than a stone in weight loss (6kg).

But for those who need to shift a greater amount of weight, fast, Dr Mosley has also designed a more drastic version of the diet. It could help you lose 2st (12kg) or more.

Cleverly, both plans use the same Mediterranean diet-inspired recipes that can all be made in two ways – with a low-calorie version for fasting days, and a higher-calorie version to eat when you're not restricting yourself but want to eat healthily.

And, if you don't have much weight to lose, just eating the higher calorie version of the recipes and sticking to a few simple Med-diet rules should help you tone up a bit...

THE NEW 5:2 DIET

The 5:2 diet is all about an approach known as intermittent fasting, or IF. A more accurate description would be "intermittent calorie restriction" because what you are doing is cutting back on your calories two days a week, albeit rather dramatically.

It is an approach Dr Mosley pioneered several years ago and which formed the basis of The Fast Diet, a book he wrote with Mimi Spencer.

The 5:2 involves eating healthily five days a week, then cutting your calories down to about 800 for the remaining two days, which he calls Fast Days.

Originally, it was 500 calories a day for a woman, and 600 for a man – roughly a quarter of the recommended daily intakes – simply because that was the version of IF he'd done himself, with huge success.

But quite a few people told Dr Mosley that they struggled to adapt to just 600 calories a day. Going up to 800 does not seem to significantly slow weight loss and many people find the extra calories really help.

PROOF THAT THE 5:2 REALLY WORKS

The person who first inspired Dr Mosley to try intermittent fasting was Dr Mark Mattson, a professor at Johns Hopkins University in the US and one of the world's leading neuroscientists. He has been researching the benefits of intermittent fasting for more than 20 years.

Dr Mosley went to see him in 2012, soon after he had been diagnosed as having type 2 diabetes. He convinced Dr Mosley that IF would not only improve his waistline and his blood-sugar levels, but also his brain.

He'd done numerous studies, albeit mainly with mice, which showed that cutting calories a couple of days a week can protect the brain from dementia and lead to the production of new brain cells, particularly in the areas associated with memory.

Dr Mosley decided to see what would happen if he cut his food intake to about a quarter of the recommended 2,500 calories a day for two days a week, and do this for eight weeks.

Dr Mosley found it surprisingly easy to do and, on what he was now calling a 5:2 diet, he lost 20 lb over 12 weeks, reversed his diabetes and took four inches off his waist. Six years later he's maintained both the weight loss and improved blood-sugar levels.

The science behind the benefits of IF is strong and getting stronger.

Eating like this will help you lose weight (particularly fat around the middle) but it also triggers a cascade of changes within the body that can reduce your risk of a range of diseases.

A recent review article published in the scientific journal Cell Metabolism concluded that IF reduces many of the things that encourage ageing, such as "oxidative damage and inflammation", while increasing the body's ability to protect and repair itself.

The article concluded that it "helps reduce obesity, hypertension, asthma, and rheumatoid arthritis. Thus, fasting has the potential to delay ageing and help prevent and treat diseases."

HOW TO MAKE IT WORK FOR YOU

Lots of people on the 5:2 have asked Dr Mosley: "What is the best way to divide my calories on Fast Days? Should I skip breakfast and split them evenly between lunch and dinner, or skip dinner and have a hearty breakfast? Should I eat three meals, or just one a day?"

The honest answer is that it entirely depends on what you can handle.

There is some evidence that having an extended period without food, even on days when you are not "fasting", can be beneficial, and many of the experts he talk to do just that.

In other words, you might want to try eating all your meals within an eight-hour window, which either means skipping breakfast or having an early dinner.

For a lot of people, neither is practical, which is why he doesn't make hard and fast rules about this.

THE 5:2 GOES MEDITERRANEAN

For Dr Mosley's New 5:2, he's combined IF with everything we've learned about the Mediterranean diet, a way of eating that has been shown to be incredibly healthy.

You may think of a Med diet as heaps of pasta and pizza, but it's not. A traditional Mediterranean diet is rich in fish, olive oil, nuts and legumes, with the occasional glass of wine.

It is relatively low-carb and involves cutting right down on cakes, biscuits and other sugary treats.

Unlike trendy very low-carb diets, his approach still finds space for plenty of healthy carbs such as fruit, deliciously cooked green and coloured vegetables and the occasional treat.

It also contains lots of lovely things that down the years we have been told not to eat, such as eggs and full-fat yogurt.

The main thing about a Mediterranean-style, low-carb eating plan is that it is a tasty and healthy way of living. It is packed full of disease-fighting vitamins and compounds called flavonoids.

Proven benefits of the Mediterranean style of eating include a reduced risk of heart disease, type 2 diabetes and weight gain.

HOW TO SEAL YOUR SUCCESS

People who do the New 5:2 can expect to lose about 12 lb in 12 weeks, with most of it coming off in the first month.

It is safe and effective. One reason why the 5:2 approach has been so successful is because you aren't dieting all the time.

Dr Mosley certainly finds it easier to resist the temptation to eat something unhealthy by saying to himself: "I will have it tomorrow."

Then tomorrow comes and maybe I'll eat it, but often I don't.

There is also evidence that intermittent fasting shrinks the stomach, meaning you are less likely to want to gorge on your non-Fast Days.

That said, some of the non-weight loss benefits of intermittent fasting seem to come from the fact that it is quite challenging.

It is a bit like exercise: pushing yourself really does seem to be the best way to get results. One reason this happens is because when we are stressed, at a cellular level, hundreds of protective genes spring into action.

Going without food for short periods also switches on a process called autophagy, allowing the body to clear out old damaged cells, making way for new ones. The main way to succeed with any diet is to prepare.

1. RESTOCK YOUR CUPBOARDS

Before you buy the ingredients for the recipes, make sure you clear your cupboards of temptations.

It might sound obvious but if sugary snacks are lying around, unless you have superhuman willpower, there will come a time when you will eat them.

If you have children and feel you have to have sweet or savoury treats in the house, it's a bit more of a challenge.

If you are fortunate enough to have a partner who isn't a sugar fiend, get them to keep the treats in a locked cupboard.

The safest course of action is to give it all away. The junk has to go. It will leave space for healthier foods.

2. WRITE DOWN YOUR GOALS

When you are in the thick of a new eating regime, you will inevitably have moments of doubt or forget why you are putting yourself through it.

So before you start, jot down all the reasons why you want to get in shape and stay healthy.

Keep it with you. Read this list whenever you feel yourself weakening. Make the reasons as specific as you can.

3. FIND YOURSELF A DIET BUDDY

We are social creatures and doing a diet with your partner or a friend will significantly improve your chances of success.

Once you've decided that you want to go on this diet then tell your friends and family about it.

They may know someone else who wants to do it with you. The fact that you are making a public commitment also means you are more likely to stick to it.

Now it's time to get started. The sooner the better. After all, summer is just around the corner…

FIVE TOP TIPS FOR 5:2 SUCCESS

1. Record your weight, your body mass index (BMI) score, and your waist size at the start.
   
   Waist measurement is a simple and important gauge of internal fat and a powerful predictor of future health.
   
   BMI is your weight (in kilograms) divided by your height (in metres) squared; you can find plenty of online calculators.
   
   A BMI of 18.5 to 25 is considered optimal.
   
   
2. Prep your Fast Day food in advance so that you don't go foraging and come across a leftover sausage lurking irresistibly in the fridge.
   
   Shop and cook on non-Fast Days, so as not to taunt yourself with unnecessary temptation.
   
   Keep it simple, aiming for flavour without effort.
   
   
3. Stay busy. Fill your day, not your face.
   
   Engage in things other than food – not necessarily skydiving, but anything that appeals to you.
   
   Distraction is your best defence against the dark arts of the food industry, which has stationed doughnuts on every street corner and nachos at every turn.
   
   If you absolutely must have that doughnut, it will still be there tomorrow.
   
   
4. Stay hydrated. Find no-calorie drinks you like, and then drink them in quantity.
   
   Some swear by herbal tea; others prefer a mineral water with bubbles, though tap water will do just as well.
   
   When you are burning fat you are also losing water, so you will need to compensate with additional drinks beyond your routine intake.
   
   The recommended eight glasses of water a day is as good a guide as any.
   
   A full glass of water is a quick way to hush an empty belly, at least temporarily. It will also stop you mistaking thirst for hunger.
   
   
5. Be sensible, exercise caution, and if it feels wrong, stop.
   
   It is vital that this strategy should be practised in a way that is flexible and forgiving.
   
   If you're concerned about any aspect of intermittent fasting, see your doctor. Remember, it's not a race to the finish, so be kind to yourself.

This article was first published on dailymail.co.uk and is republished here with permission.