Look, we've all done it. At one point or another we've all succumbed to some BS diet, whether it be s**tting yourself to tears on a weird lemon detox diet, ditching carbs, doing meal replacements or fasting for hours on end.

And to be honest, the odds are kinda stacked against us. Like, can you kindly name a period in history where women's bodieshaven'tbeen under scrutiny? We'll wait.

Watch: Sarah Wilson gets real about dieting. Post continues below.

Because while diets may seem like a modern day and social media-fuelled phenomenon, the desire to lose weight quickly has been around for... well, ever.

From drinkingonlyalcohol (yes this was a thing) to swallowing tapeworms (also a thing that people did) and eating grapefruit with every meal (seriously, though), crazy diets have been kicking around for centuries.

Listen to our deep dive about diets on this ep of The Quicky. Post continues below.

But please, riddle us this: how is it still a thing in 2021?

These days we're getting around with all this advanced scientific and medical knowledge, so you'd kinda think fad diets would be a thing of the past, no?

Nah.

You talk to your friend Rachel and she's on the Keto diet so she can lose three kilos for her wedding. You check your inbox and see a special offer from a weight-loss company. You scroll through Instagram and see all these influencers pushing new meal replacement shakes and tea that makes you poo for 24 hours straight.

Diet culture is still very much a thing. And no matter how far-fetched these faddish ideas are, for some reason they continue to appeal to people.

While there's heaps of research out there that shows dieting for weight loss is not a thing that works in the long-term, we're all still out here throwing our hard-earned pennies into these health crazes and just hoping for the best.

¯\_ (ツ)_/¯

So, what's the go?

Why are we still talking about diets?

"The psychology around health fads, new products and health related myths is really interesting, and it hits right to the core of some of the biggest drivers for human behaviour," explains medical doctor and psychiatry resident Dr Kieran Kennedy.

"One of the reasons fad diets might be so tempting is because they don’t just represent a ‘diet’, they represent the hopes, fears, anxieties and goals we carry around with us on a much deeper level."

Sheesh.

According to Dr Kennedy, diets are often coupled with the pressure that society places on us to "align our self worth with our appearance."

That old chestnut.

He said they also often promise (either directly or indirectly) things like "greater confidence, better relationships, more success and greater longevity."

While the lure of 'looking better' and losing a few inches off your waist is an inherently strong driver behind the push behind fad diets and health crazes, Dr Kennedy said "it’s a complex mix of body image, appearance pressure and the drive we all have to feel better and healthier."

But surely we know we're not going to get any long-term benefits out of doing them, right?

"We know diets don't work, but when our self-worth is tied to the size of our clothes instead of our talents, it's scarily easy to do very unhealthy things to your body in order to weigh less," said Lyndi Cohen, dietitian and founder of Keep It Real, an online program to end binge eating and the Back to Basics App.

According to Cohen, most weight-loss diets are simply "eating disorder advice in disguise", and they're appealing to us because they promise fast solutions.

For many of us, giving up your favourite foods for life (hey, chicken nuggets) seems daunting, no? So, more often than not, these kinds of programs are catered as a 'quick fix' and something you follow for a few weeks.

Obviously not healthy. Or logical. But, yeah - that's where we're at.

"We overlook the fact that they are unsustainable and weight regain is almost inevitable. Fad diets are appealing because they have rules that are easier to follow than general eating advice," said Cohen.

"It's easier to cut out sugar from your diet for a month than to learn to have a healthy relationship with it. Fad diets are a shortcut, but they aren't sustainable – no matter how hard we try."

Meanwhile, experts have been giving the same advice they've been throwing around for years: There's no quick fix.

Fiona Tuck, nutritionist and founder of Vita Sol said, "The ironic thing is that good nutrition is pretty basic but for some reason we want to over complicate it or look for a conspiracy theory."

"With the rise in social media, everyone has a platform and many people are promoting themselves as experts so we have an overload of education, information and marketing. Often the simple message of healthy eating is getting lost," said Tuck.

Meaning? People are picking and choosing what information they want to hear (rather than what's actually beneficial to their health) and just running with it.

And it's not just influencers and social media that need to pack the blame when it comes to the unhealthy diet culture that's still floating around - Tuck said the media is also partly responsible.

"The click bait news grabbing headlines of scaremongering certain foods or promoting miracle diets gets attention," she said.

"Taking a sensible approach to eating, by eating more plant-based foods and fibre, doesn't. If this was promoted more, then fad diets may finally become a thing of the past."

The kicker? Jumping in and out of crash diets isn't just torturing your taste buds - it could seriously be messing with your health.

"Most fad diets, ‘miracle’ products or new health crazes come with claims and promises that aren’t backed up by evidence, and might even pose some health risks," said Dr Kennedy.

The biggest diet fads of 2021.

There's a lotta fad diets kicking around. We've all seen them - hovering around, trying to catch your eye and lure you in with their fluffy promises and seemingly easy solutions.

So, we asked our experts to help us dissect some of the trendiest diets for quick weight loss (ones we'd obviously never recommend trying), to find out the facts.

1. Ketogenic diet.

Known as the Keto diet, this particular program is all about ditching carbs in replacement of high fat eating.

"The Keto diet is basically the Atkins diet that's been rebranded and made more extreme. It's an exceptionally low-carb diet, which will impact your ability to eat out and socialise," said Cohen.

The Keto diet was originally used under medical supervision to treat severe epilepsy, said Tuck - mainly in children that did not respond well to seizure medication.

And now it's been... transitioned into a diet to promote fat loss.

"This is due to the severe restriction in carbohydrates and the high fat intake which puts the body into a state of ketosis - meaning because the body is not getting its energy from carbohydrates, it has to use fat instead of glucose for fuel," Tuck explains.

According to Tuck, clinical ketogenic diets usually limit carbs to between 20 to 50 grams per day, with 30 grams per day being the average.

If these numbers sound ridiculously tiny - that's because they are. To put this into perspective, one cup of cooked oats (in water) is approximately 28 grams of carbohydrates.

One cup of oats, friends.

When it comes to the protein side of things, Tuck said this part is *really* stringent. "Protein intake needs to be kept at a level that is high enough to ensure that lean body mass is not lost, but low enough to maintain the body in a state of ketosis."

Is it a quick way to lose weight? Yeah, sure. If you get all your fat requirements right.

Is it sustainable? Nope.

Is it good for you? HA. (No. No, it's not).

Looking at short-term effects, you'll probably feel sluggish from no carbs (your body needs carbs for fuel btw), and the lack of fibre might even back things up a bit (sexy) and mess with your gut. Long term you could experience high cholesterol and heart issues - because high-protein diets are usually high in saturated fat.

"One of the biggest issues I (and many doctors) have medically with diets such as these is that they often come with sweeping claims that aren’t actually backed up by solid silence," said Dr Kennedy.

"Not only is this misleading (and a part of why we’re so often roped into trying them out), but it comes with dangers as well."

According to Dr Kennedy, the Keto diet is a prime example of this "with many online resources and books linking keto-life to a longer life, better skin/hair, improvements in mental health conditions and even lower cancer risks."

"While there are a small number of areas where a ketogenic diet can have a significant impact on health (such as for certain cases of epilepsy), the vast majority of these claims don’t actually hold any water," he adds.

2. Intermittent fasting.

Heard of it? Course you have. It's everywhere.

"There are different types of fasting however they all involve eating within a time restricted window.

"The 5:2 diet become popular a while back and the 16:8 is the recent most popular form of intermittent fasting," explains Tuck.

"This involves restricting food intake to an eight-hour window and not eating (i.e. fasting) for the remaining 16 hours."

There is evidence out there that intermittent fasting may result in weight loss most likely due to the reduced window of time to eat. There are also studies that show it can improve blood sugar, cholesterol, digestive function, brain function and longevity.

Sounds like it's nottoo bad, but while it may come with some benefits, Tuck said it is restrictive and you really have to be eating the right kinds of foods in order to see any changes.

"It is important that the food eaten within the time restricted window is nutrient dense to ensure the adequate nutritional needs and calories are being met," she said.

"Intermittent fasting is not as simple as starving yourself and then binge eating on junk food. To really gain benefits it is advisable to follow a healthy eating plan."

So, is it sustainable? Does the weight stay off once you've lost it?

"Here's the thing. All diets work until they don't work," said Cohen. "Anyone can lose weight by following a diet that isn't sustainable."

"Eventually, you realise you don't want to live the rest of your life without bread or pasta or you realise you are sick of not eating enough to fuel your body. When you can no longer maintain the strict rules needed to lose weight on a diet, you'll most likely regain the weight plus more," said Cohen.

And it's not just your physical health than can take a beating here - it's your mental health too.

"There’s robust research to show that restrictive diet methods, especially those that label certain foods as ok or not, pose increased risk for developing eating disorders. We need to be really mindful that it’s not just our physical health or waistline that gets impacted by a diet, it’s our mental health as well," said Dr Kennedy.

3. Sirtfood diet.

Popularised by celebrities like Adele and Pippa Middelton, the Sirtfood diet is basically a calorie-restricted diet with a ~fancy~ new name.

Pretty sneaky, huh?

And there's a bit of controversy surrounding the eating plan. Of course.

It basically promises that you can lose up to seven pounds (roughly three kilograms) in seven days, which is pretty insane given that most experts recommend that 0.45 and 0.9 kilograms weight loss a week is healthy.

Not only this, but the way in which you're encouraged to lose the weight is highly restrictive, and a lot of critics have said that it's highly untenable/utter crap.

So, what is the Sirtfood diet and what's it based on?

"The Mediterranean diet for example, known to be the healthiest diet in the world, is full of 'sirt' foods. Eating a