Calling all yo-yo dieters! Whether you want to bulk up or slim down, we weigh up the most popular food regimens.

No carbs before Marbs. No pizza before Ibiza. Master cleanses, juice detoxes, beach-ready challenges. Instagram is on an extreme #eatclean #fitfood diet like never before. These days, our feeds are full of overhead shots of artfully arranged avocados (see our best brunches piece), shameless six-pack selfies and Lycra-clad before-and-after portraits.

Not so many years ago, real men didn’t go on diets, or certainly didn’t admit to it. All that has changed. According to Mintel, a record-breaking 29 million Brits tried to slim down in 2013 – that’s more than half the adult population – and 44 per cent of them were men. We all want to look good in our Orlebar Browns come summer, and no one wants to bust out of the suit they had made last year.

We have been fixated by celebrity diets since the early 1800s when Lord Byron, who was obsessed with his weight, embarked on various extreme regimes, including subsisting on apple cider vinegar and water. (Indeed, “drinking vinegars” are going to be the next big health craze according to Mr Alex Matthews, co-founder of LA wellness brand Juice Served Here.)  Mr Elvis Presley, who famously struggled with his weight until the end, would undergo sedation for days at a time in order to avoid eating. Some of today’s celebrity-endorsed fads are almost as extreme. The idea for this article came after the Whole30 craze (see below) swept through the MR PORTER offices in January like a wasting plague. What follows is an informed evaluation of six of the most popular regimes doing the rounds at the moment.

As someone who has tried and tasted more than a few diets over the years (my previous job was working for a health and fitness magazine), I have cherry-picked a few common-sense dietary principles:

01. The secret to weight loss is no secret at all. You simply have to create a calorie deficit by expending more calories than you ingest. Which generally means exercise a bit more and eat a bit less.

02. Eat foods with very few ingredients, all pronounceable, or better still, no ingredients listed at all because they’re totally natural and unprocessed.

03. Cut down on what surfer Mr Laird Hamilton calls the “four white devils”: flour, dairy, salt and sugar.   

04. For a well-balanced mind as well as diet, follow the 80/20 rule. If 80 per cent of what you eat is super-healthy, the other 20 per cent can be less so. No one wants to live like a monk.

05. Everything in moderation, including moderation.

Until I work out how to package these self-evident guidelines into a best-selling self-help book, it’s worth examining the crazes currently circulating. In the battle of the fad diets, which one is the safest bet and which one is the biggest loser? Let’s weigh in.

What?

Intermittent fasting (IF) has been around for centuries (it’s often done for religious purposes), but the 5:2 Diet put it back in the spotlight in 2012 when Dr Michael Mosley, a doctor and award-winning journalist, presented a well-received BBC documentary called Eat, Fast And Live Longer, a weight-loss plan with longevity benefits. He subsequently published The Fast Diet.

Best for:

People who want to reduce their size and lose weight, but haven’t the patience or bandwidth for a complicated diet full of rules and restrictions.

Who does it:

Messrs Benedict Cumberbatch, Jude Law and Jimmy Kimmel have all been reported to be practitioners; Mses Miranda Kerr and Jennifer Lopez, too.

How it works:

There are many variations of IF (such as ADF, alternate-day fasting), but we’ll focus on the most popular – the 5:2 plan. This means eating “normally” for five days of the week (about 2,500 calories per day for men), and fasting on the other two days (about 600 calories per day). The standard advice when it comes to diets is not to skip meals so that you don’t slow your metabolism down, but this plan turns that on its head. Eating this way is thought to increase the fat-burning efficiency of our metabolism and inhibit fat storage.

Weight loss is just one of the reported benefits of IF. Studies show improvements in blood pressure, cholesterol levels and insulin sensitivity. Calorie restriction – eating well, but not much – is one of the few things that has been shown to extend life expectancy. The 5:2 is simple compared with other diets and it won’t cost you any more money (it should cost you less, in fact) – and, on “feast” days, it allows you to eat normally at social events.

Fasting doesn’t work for everyone. You can expect to be “hangry” on your fasting days, but some people feel shaky and light-headed, anxious or headachy. You may need to experiment to figure out what rhythm of fasting works best for you. There’s always the possibility that you end up bingeing on the “feast” days because you’re so hungry and feel that you’ve earned it, which will undo the good work of the preceding fast. You still need to eat healthily in order to create an overall calorie deficit and lose weight.

**Verdict:**4/5

What?

This low-carb, high-fat diet was conceived many years ago as a drug-free way to control epilepsy seizures, but in recent years, South African exercise physiologist Professor Tim Noakes has popularised it for more widespread application.

Best for:

Endurance athletes who want to boost performance legally, and overweight people who want to slim down – not types often seen in the same diet category.

Who does it:

Mr Tim Ferriss, influential author of the 4-Hour self-improvement series, has backed it. Apparently, Sir Mick Jagger has, too. And Mr Zac Efron. An eclectic group of endorsees.

How it works:

An updated modification of the Atkins Diet, this is a low-carb, high-fat regimen that is also high in protein and extremely low in sugar. The ratios are approximately 70 per cent fat (butter, olive oil, avocado, nuts, oily fish), 25 per cent protein and 5 per cent carbohydrate (from low-glycemic vegetables). Eat fat to lose fat? Sounds counterintuitive, especially for a generation brought up to believe fat is evil. The idea is to induce a metabolic state called ketosis by markedly limiting carbohydrates so your body burns energy from fat instead of from glucose, and limits fat storage by reducing insulin.

This one appears to have some scientific rigour behind it. It makes your metabolism more efficient by speeding up the rate of calorie burn and reducing fat storage. It helps suppress appetite, so you eat less, and it’s good for endurance (although some people report a lack of energy, so that is subjective).

It can make eating out difficult. Because you’re drastically cutting down on fruit and vegetables, you need to ensure you don’t become nutrient and vitamin deficient. There is a two-week adaptation phase while the body recalibrates, which can be uncomfortable. Ketosis makes your breath and urine smell similar to nail polish remover.

Verdict: 3.5/5

What?

The diet of cavemen, presumably, but the CrossFit craze has popularised it.

Best for:

Those who want to put on muscle. With its caveman connotations, this is a particularly macho diet. It’s also good for those who are gluten free.

Who does it:

Hollywood pin-up Mr Matthew McConaughey is the poster boy; adventurer Mr Ray Mears less so. It’s the kind of diet most muscle-bound action heroes eat in the build-up to shirtless scenes for comic-book movie adaptions.

How it works:

Named after the prehistoric Paleolithic era, the premise is: if they didn’t eat it 30,000 years ago, we shouldn’t eat it now. Stone Age man didn’t gorge on pies and fries. This hunter-gatherer diet is completely devoid of grains, dairy, sugar, alcohol or any other processed or refined foods such as corn, potatoes and peanuts.

The fact that the occasional cheat meal with a glass of alcohol is permitted makes this diet more realistic and easier to stick to. There aren’t loads of rules and no calorie counting, so once you’ve got the basic principles, it’s not complicated to follow.

Eating lots of meat ends up an expensive business – and can give you bad breath. Cutting out entire food groups such as dairy and grains puts you at risk of nutrient deficiency, including calcium deficiency in bones – something to bear in mind if you’re dragging your knuckles.

Verdict: 3/5

What?

Mr Dallas Hartwig and his ex-wife Ms Melissa Hartwig, sports nutritionists and co-authors of bestseller _It Starts With Food, _created the Whole30 Program in 2009 as a “short-term nutritional reset, designed to help you put an end to unhealthy cravings and habits, restore a healthy metabolism, heal your digestive tract and balance your immune system”. Their premise is that all facets of health – from susceptibility to illness to energy levels to self-esteem to body composition – start with food.

Best for:

Competitive types who revel in a tough short-term challenge. It swept through the MR PORTER offices at the beginning of this year.

Who does it:

Basketball stars Messrs Kobe Bryant and LeBron James have been linked to it.

How it works:

More than a diet, if you follow Whole30, it will completely change your life. Paleo’s more extreme cousin, Whole30 is designed to help you identify food groups that disagree with you. So after the month, rather than following a one-diet-fits-all regime, you should begin to figure out something that works specifically for you. For 30 days you have to eliminate all processed food, sugar, grains, dairy, legumes and booze. Essentially, you survive on meat, fish, eggs and vegetables. The purpose is to help you discover what your body needs and what it doesn’t. By cutting out these things for 30 days and gradually adding them back in, you begin to understand how food changes you.

The goal ostensibly is to decrease inflammation and lose weight, but Whole30 claims it will also reduce stress, give you more energy and even better skin. It can also help you eliminate cravings so your diet stays healthy after the 30 days are up.

The miracle health claims sound like a late-night infomercial and there’s little or no real science to back them up, only anecdotal testimonies. Even if you feel better on the diet than off, you aren’t any closer to figuring out which of the many forbidden foods was the problematic one. You then have to experiment with the ingredients individually, which you could do without going through Whole30 first. This diet is formidably strict. The plan claims that even the smallest amount of food from the No List will break the healing cycle of the programme, regardless of circumstance. So if you mess up (a dash of milk in your coffee, some sauce with your meat, even a few evil lentils in your salad), you have to start again from day one. This makes it very difficult to stick to, especially if you have a social life. Eating out suddenly involves long and tedious conversations with waiters about ingredients. Whole30 followers can become boringly obsessed with the whole thing. (No offence to any of my MR PORTER colleagues – hey, have you been working out?)

Verdict: 2/5

What?

This regimen was devised by white-haired diet guru Dr Pierre Dukan, who was (voluntarily) struck off as a doctor in France in 2012, basically for ramming his diet down people’s throats. His 2000 book has sold more than 11 million copies, so he probably doesn’t need to work anymore, but health professionals deem the regimen irresponsible. The British Dietetic Association slammed it as one of the “top five most dangerous fad diets”.

Best for:

Those who want to lose a few pounds quickly before a party or a beach holiday – you’ll see dramatic effects in the first week – and yo-yo dieters (people who put weight back on straight after losing it). The Dukan Diet’s USP is lasting results if you stick with the second two phases.

Who does it:

This one is very female-skewed. The Duchess of Cambridge, Mses Jennifer Lopez, Penelope Cruz and Gisele Bündchen have all tried it, apparently. Couldn’t find any notable men willing to put their name and frame to it. Who does not do it? Vegetarians and vegans.

How it works:

Or rather, doesn’t. It shares some foundation with the Atkins Diet in that it is high protein, low carb – only it’s more extreme and strict, especially at first. The book makes it sound easy. You can eat as much as you want of 100 foods – no calorie counting or going hungry. But it’s a very strict and quite boring diet (100 foods sounds like a lot, but it isn’t), so it is hard to stick to. The Dukan Diet is split into four phases: the first two target losing the weight, the second two help keep it off. During the first phase, Attack, dieters can eat only lean protein, drink six glasses of water per day, walk for 20 minutes, and eat at least one-and-a-half tablespoons of oat bran. You then move on to the Cruise Phase, which follows the same process, but allows dieters to add in low-starch vegetables. During the third phase, Consolidation, dieters can add in one serving of fresh fruit and two slices of wholegrain bread per day. In the final phase, Stabilisation, dieters can eat whatever they like, but must return to eating only protein for one day each week.

You’ll see dramatic results quickly in week one, which encourages people to crash diet. Is that a pro? No, it isn’t. But we couldn’t leave this section entirely blank.

It’s been heavily criticised for being an imbalanced diet. No fruit or vegetables in the Attack phase means precious few vitamins and minerals. Plus, it gives you a dry mouth, shocking breath and can make you feel weak and dizzy.

Verdict: 1/5

What?

VB6 (Vegan Before 6.00pm) is one of the catchier flexi diets, and is the brainchild of influential New York Times food writer Mr Mark Bittman.

Best for:

People who want a long-term, sustainable healthy-eating lifestyle rather than a crash diet.

Who does it:

Beyoncé and Jay Z have given this one a go.

How it works:

Meat-free Mondays not enough? Flexitarian is a catch-all term for going mainly vegetarian, or even vegan – ie, reducing the amount of animal products in your diet without completely giving them up. Cutting down on (red) meat is better for your health and the environment, but as the name suggests, flexitarianism is vague. A specific plan is VB6: eating like a vegan before 6.00pm, which means you can eat whatever you like at dinner, within reason. It’s about eating better or well, rather than perfectly.

This is a happy medium rather than an extreme regime. You can have your cake and eat it. You get most of the health benefits of veganism without having to give up all your favourite foods. Your diet will certainly be healthier with less saturated fat, processed food and junk, but VB6 doesn’t need to interrupt your social life. It’s a workable, sustainable food plan for you and the environment.

Weekend brunches are tricky, and you may not lose weight – it really depends how careful you are after 6.00pm. The lack of regimented rules sounds attractive, but in practice, it doesn’t work for those who need absolute clarity.

Verdict: 4/5