The science behind 33 weird celebrity diets, from Kim Kardashian's Met Gala weight loss to Heidi Montag eating raw meat

The sirtfoods diet is claimed to help lower inflammation, slow aging, and boost weight loss while enjoying berries, greens, dark chocolate, and red wine.

The eating plan was popularized in 2019 after a rumored connection to pop star Adele.

However, she said in a recent Vogue interview that she hasn't followed any particular diet, and "inside sources" claiming to have spoken to her were unreliable.

"All these other people have come out saying that they trained me," Adele told Vogue. She called them "weirdos," adding, "I've never met them in my life!"

The sirtfoods diet was initially launched by a 2016 book claiming that the specific foods could activate a protein called sirtuin, which may support healthy metabolism and longevity.

But more research is needed to back up the benefits of sirtfoods. As of now, while the foods on the diet are healthy, they're not likely to have any particular weight loss benefits, experts previously told Insider.

The diet also involves a strict calorie-cutting phase of 1,000 to 1,500 calories daily, which experts have previously said is dangerously low for adults.

Joe Rogan said he followed a diet of just meat and fruit to kick off 2022, following up on his previous foray into animal-based diets that he said

The controversial podcaster has previously hosted high-profile proponents of meat-only eating, including Canadian psychologist Jordan Peterson.

Since then, the so-called "carnivore diet" has developed into a major diet subculture, complete with its own influencers, social media groups, and insider jargon.

Proponents say cutting out all plant-based foods and eating only animal products can boost weight loss, improve mood, and heal certain ailments such as autoimmune disorders.

Experts say there may be some benefits linked to eating meat, which is a rich source of nutrients, especially if people are eliminating unhealthy processed foods from their diet.

But while research on the carnivore diet is ongoing, the long term effects on health aren't clear. Eating only meat could have health consequences, since studies suggest plant nutrients like fiber and polyphenols are protective against heart disease and cancer, experts previously told Insider.

Kim Kardashian is no stranger to diet controversy, but her 2022 weight loss for the Met Gala prompted concern from experts who said the "extreme" tactics could be unhealthy.

Kardashian said she lost 16 pounds in a matter of weeks by cutting out sugar and carbs, "just the cleanest veggies and protein."

She also said she ran on a treadmill and wore a sauna suit to further shed pounds.

But rapid weight loss isn't sustainable and may not help with fat-burning, especially long term, a dietitian previously told Insider's Rachel Hosie.

Cutting carbs and cardio may result weight loss initially, much of which may be water weight, but can often lead to rebound weight gain known as "yo-yo dieting" that may worsen health issues over time.

For healthy weight loss, a goal of about one or two pounds a week is what experts recommend, ideally through making small, achievable changes to lifestyle and daily habits.

Heidi Montag said she started eating raw meat to improve her fertility, as part of her interest in anthropology and "the way humans are meant to eat."

She was seen walking through Los Angeles eating from a clear plastic bag filled with raw meat, and told PEOPLE that she enjoyed eating organs "sushi-style" to preserve the nutrients.

It's true organ meats contain plenty of vitamins and minerals that can benefit health, such as iron, zinc, folate, and B vitamins that can be good for energy levels as well as fertility.

But raw meat is risky, potentially contaminated with bacteria and parasites that can make people seriously sick.

Potential pathogens in raw meat and organs include E. coli, salmonella, Campylobacter, and listeria, registered dietitian Bonnie Taub-Dix told Insider.

"When you eat raw meat you run the risk of developing food poisoning," Taub-Dix said. Some raw meat may also contain parasites like roundworms or tapeworms.

Former Spice Girl Victoria Beckham has kept the same diet for more than two decades, eating fish and vegetables almost exclusively, according to her husband.

Soccer star David Beckham said in early 2022 that while he's a foodie, his wife will "very rarely deviate" from her go-to meal of grilled fish and steamed veggies.

She later joked about the incident on TikTok, and clarified that while her diet is "disciplined," she also enjoyed healthy fat sources like avocados and nuts, and drinks alcohol regularly.

Trying a wide variety can be a good way to get enough vitamins and minerals, so eating the same foods every day can make you miss nutrients, a dietitian previously told Insider.

It all depends on personal preference and what you're eating.

Try to include protein and produce like veggies and fruit every time you eat for healthy, satisfying meals, recommends registered dietitian Brigitte Zeitlin. So long as you're getting enough nutrients, eating similar foods can be convenient, she said.

Actress Rebel Wilson overhauled her lifestyle in 2020, declaring it her "Year of Health."

As part of the changes, she reportedly followed a diet based on the theories an Austrian physician developed about health 100 years ago.

The Mayr Method, named for Dr. Franz Xaver Mayr, is a complex set of habits that has become the basis of treatment at Vivamayr, a chain of luxury wellness and medical spas beloved by celebrities.

Experts say the Mayr Method is a mix of good advice and pseudoscience nonsense.

For instance, the diet emphasizes "mindful eating" or slowing down to enjoy the experience of your food, which can be a great way to get in tune with your appetite and avoid overeating. However, the diet's instruction to chew each bite at least 40 times is excessive, according to dietitians.

Similarly, the Mayr Method's principles of cutting out caffeine, sugar, and dairy, not snacking between meals or eating raw food after 4 p.m. aren't science based.

The diet's so called "high alkaline" foods like fruits and veggies are healthy, but because they're nutrient-dense, not because they actually balance your pH level, the experts said.

Seven-time Mr. Olympia Arnold Schwarzenegger eats a mostly plant-based diet and is outspoken about the health benefits, including lower cholesterol and "feeling younger."

But the iconic bodybuilder also treats himself, with occasional steak or Austrian wiener schnitzel and, he revealed, a shot of alcohol in his protein shakes.

Schwarzenegger said he started adding booze to protein shakes in hopes of helping the protein absorb more quickly, but now enjoys the extra flavor from tequila or schnapps, he told Insider's Rachel Hosie.

While alcohol won't necessarily derail your fitness gains, too much drinking can actually make it harder to absorb protein to repair and build muscle, research suggests.

And being excessively inebriated, or having a hangover, can make it harder to work out, eat nutritiously, and keep up with other healthy habits over time.

NFL quarterback Aaron Rodgers said he cut out sugar, sex, and alcohol and consumed warm butter and laxatives as part of an intensive 12-day cleanse.

Called a Panchakarma, the cleanse originates in Ayurveda, a traditional healing practice from India, and is meant to heal the body and mind.

The basic structure of the cleanse involves drinking warm clarified butter or ghee in the morning to "lubricate" the system, and having laxative tea at night to "detox," according to the Ayurvedic Institute. Practitioners are also encouraged to eat only specific foods like rice and mung beans and avoid cold food and drinks. In some cases, the process may involve "therapeutic vomiting," enemas, and bloodletting.

There are no evidence-based health benefits to the practice, according to experts. Your body naturally completes any detoxification necessary through your liver and kidney, and supplements claiming to help cleanse often don't work or do more harm than good, leading to dehydration or digestive issues.

Multiple celebrities have tried to subsist only on uncooked plant-based foods with a raw vegan diet, including tennis star Venus Williams and actress Anne Hathaway.

Williams went vegan in 2011 after being diagnosed with an autoimmune disorder, and said a raw vegan diet helped her symptoms.

She told Insider in 2019 that she started eating potatoes, lentils, and other cooked foods for more energy and nutrients.

"Sometimes you just need something more substantial," she said.

Williams has stayed vegan, among a growing number of high-profile vegan athletes like Alex Morgan and Chris Paul who swear by a plant-based diet for better performance.

Hathaway went raw vegan for a role, portraying yoga instructor Rebekah Neumann in "WeCrashed."

She had previously dabbled in veganism, but never for long, and said in interviews that the diet didn't make her feel "strong" or healthy.

Going vegan can have health benefits, including for athletes, such as more energy and better recovery. However, vegans can have difficulty getting enough of some nutrients. Plant foods tend to be low in calories, especially when raw, which can be a challenge for athletes trying to eat enough.

Intermittent fasting, or limiting your meals to a specific window of time each day, has become a popular diet to speed weight loss and reduce the risk of chronic illness.

Celebrities have picked up the diet to help transform their bodies for specific roles.

Marvel star Chris Hemsworth used intermittent fasting to quickly lose weight to play a shipwrecked sailor for "In the Heart of the Sea," according to his personal trainer Luke Zocchi.

"Everyone thinks of him in Thor, being big and muscly, but this was the big accomplishment for me," Zocchi told Insider. "We implemented intermittent fasting, along with lower calories, and it was crazy how much that worked."

Similarly, "Stranger Things" star David Harbour said intermittent fasting helped him lose 75 pounds for the latest season of the hit Netflix series, but not without side effects.

"It really did work for me. I don't know if it's just code for starvation but it's basically like… I was hungry a lot of the time," he told GQ.

The evidence behind intermittent fasting is mixed, despite its popularity. It may help people lose weight by reducing overall calories, but a 2020 study found intermittent fasting it may not boost weight loss in every instance, and may be more likely to cause muscle loss.

The Master Cleanse is a 10-day juice cleanse that requires dieters to eat nothing and drink only a lemon, maple syrup, and cayenne pepper concoction.

Restricting calories to just a lemon drink means you won't get all of your essential nutrients. The lack of fiber, protein, and healthy fats will also likely lead to a Master Cleanse dieter feeling sluggish and hungry for the entirety of the diet.

Doing the Master Cleanse regularly could lead to heart and kidney problems, as well as long-term weight gain, according to US News & World Report.

More recently, Beyoncé has been selling access to her plant-based recipes, but the 22-day plan provides a meager 1,400 calories a day and somehow also contains a "green smoothie" with 8 teaspoons of sugar, according to the BBC.

"It could be dangerous for the average person to follow without a team of nutritionists and trainers like Beyoncé has," nutritionist Daniel O'Shaughnessy told the outlet.

"It's really hard," Carey said during an E! News interview in 2016. "My diet — you would hate it. All you eat is Norwegian salmon and capers every day — that's it."

She further clarified saying she tries to "stick to the proteins" and that it's "the worst."

Although eating protein can help keep you satiated, eating nothing but salmon means you won't get critical nutrients found foods like vegetables, fruits, and grains. It should go without saying that Carey's diet isn't sustainable for the long term.

Daniel dieters only eat fruits, vegetables, and unleavened bread for 21 days straight, with the overall goal of regaining focus on Christ-centered teachings, according to the Daniel Diet website.

Like other restrictive diets, the diet relies on the idea that the body needs to detoxify itself. But a special eating plan isn't necessary to make this happen.

"Diets that severely restrict calories or the types of food you eat usually don't lead to lasting weight loss and may not provide all the nutrients you need," the U.S. Department of Health and Human Services (HHS) explained on its website.

Known for her roles in "Divergent," "The Fault in Our Stars," and most recently, "Big Little Lies," Shailene Woodley has said she swallows a half teaspoon of clay in 8 ounces of water each morning.

"Clay is one of the best things you can put in your body," she told a beauty blog. Woodley allegedly heard about it from a taxi driver ,and says it "binds to other materials in your body" to help you get rid of "negative isotopes."

This is a bogus medical claim; your kidneys and liver don't need help processing toxins.

Clay might have trace amounts of some beneficial minerals, like iron and calcium, but there are better ways to obtain them (for instance, by eating foods rich in those minerals like spinach, broccoli, kale, and nuts).

In an 1952 interview, Monroe described her dieting choices as "absolutely bizarre," and she's not wrong. Eating raw eggs whipped into milk can lead to salmonella poisoning, and skipping lunch before a dinner of steak and five carrots could easily cause a dieter to lose out on essential nutrients. Monroe would also eat a hot fudge sundae for dessert, if you were wondering about her nightcap.

The late actress's diet appears to be an attempt at calorie restriction and a high-protein diet, but eating so little fiber and fresh produce could lead to nutrient deficiencies, heart problems, and a feeling of sluggishness.

In an effort to lose weight, Snooki did the Cookie Diet, which involves eating nine 90-calorie cookies daily in addition to a small meal at dinnertime.

The late Dr. Sanford Siegal created the plan in 1975 to help his patient eat fewer calories. The cookies contain a "secret amino acid protein blend," according to the Cookie Diet official website, but still taste like normal cookies.

Although the exact ingredients of the cookies are kept secret, the basic concept of eating one food for nearly every meal is unhealthy. It would require dieters to ensure their one dinnertime meal is packed with fresh veggies, protein, and other essential nutrients, and even then, a person may fall short of their daily nutrient intake needs.

Juice cleanses have become synonymous with celebrity diet culture. These cleanses are meant to flush the body of toxins and act as a dietary "reset," even though they aren't science-backed weight-loss methods.

Whether the cleanse involves forgoing meals altogether or replacing select meals with juice, the concept of a juice cleanse doesn't match up with human biology. The body has a built-in detox system that gets rid of toxins sans pricey sugar water.

"When we breathe, when we go to the bathroom, when our liver is functioning — the body does all the cleansing and detoxifying itself. There's no need to follow a certain diet plan to do that," registered dietitian Rachael Hartley previously told INSIDER.

Restricting calories so severely could certainly result in weight loss, but at the cost of feeling perpetually tired, hangry (hungry and angry), and being unable to keep the diet up for more than a week's time. If you tried for longer, you'd likely become nutrient deficient, experts say.

When Dorsey appeared on fitness author Ben Greenfield's podcast, he detailed his controversial diet, which involves eating just dinner every weeknight.

For his one daily meal, Dorsey has a protein (either fish, chicken, or steak), vegetables (an arugula or spinach salad, asparagus, or Brussels sprouts), and a dessert of mixed berries or dark chocolate, all of which he eats after 6:30 p.m. and before 9 p.m.

On weekends, Dorsey fats for the duration, only breaking his fast on Sunday night with bone broth. He has said the diet makes him feel more focused.

On Twitter, people said Dorsey's highly restrictive diet — an extreme type of intermittent fasting — could be a form of disordered eating, and experts agree.

"Animals who are starved shouldn't feel playful," Dr. Jennifer Gaudiani, CEDS, FAED, an internal-medicine doctor who specializes in eating disorders, previously told Business Insider. "They should feel concerned and focused. They may interpret that initially as productive, but it's the brain saying, 'I don't have enough food.'"

Brady even coined a name for his unique diet plan, the TB12 diet, and wrote a book about it. As part of his 12-step plan to stay in great shape, Brady said he doesn't eat nightshades, a group of vegetables including eggplants and tomatoes, because they cause inflammation and raise the body's pH.

But research shows eating or steering clear of certain foods can't change the body's pH enough to generate the results suggested by Brady. Plus, vegetables like eggplants and tomatoes are packed with fiber (eggplants) and vitamins A and C (tomatoes). Vitamins A and C are actually known to help reduce inflammation, contrary to what the TB12 diet suggests.

Brady said he also drinks multiple gallons of water daily to protect himself against sunburn, but there is no scientific evidence water consumption prevents sunburn.

Celebrity trainer Tracy Anderson has endorsed this diet for weight loss.

The rules are simple: baby food for every meal except dinner, which should be a low-calorie mix of lean meat and veggies.

The diet allows for 14 jars of baby food or about 1,000 calories per day (plus a measly 400 for dinner). Even if you're trying to lose weight, experts recommend burning off around 500 more calories per day than you take in, meaning this just isn't enough food for most people.

That means if you try the diet, you're probably going to be spending a lot of time with a tiny spoon while still feeling hungry.

You can achieve the main benefit of this diet, the convenience of pre-portioned foods, with a little meal prep.

The story goes that Lagerfeld woke up one day and decided he no longer liked his body. He enlisted a doctor to help him lose 80 pounds, and then the duo wrote a book about it called "The Karl Lagerfeld Diet."

Lagerfeld, who died on February 19, 2019 at age 85, drank up to 10 cans of Diet Coke daily and ate small meals to restrict his calories. For breakfast, he'd have a piece of toast, one egg, juice, yogurt, and Diet Coke. For dinner, he'd have quail eggs, salmon and Brussels sprouts, or veal with plums.

The late Lagerfeld's diet is likely to make a person feel constantly hungry. He capped his calories at 1,200 per day, according to Vox, when men are recommended to eat 2,000 to 2,500 calories daily.

Plus, drinking lots of Diet Coke without eating enough could make you feel jittery. One study even found that drinking the beverage could increase the risk of stroke or heart disease.

The Apple founder named the corporation after one of his favorite foods following a visit to an orchard. But Jobs' passion for fruit goes further than that. He practiced a "fruitarian" diet, a stricter form of veganism limited to mainly fruits and some vegetables.

A bio of Jobs reports he would sometimes turn "a sunset-like orange hue" from his strange diet, and his obsession with fasting and extreme dietary restriction has been described as a full-blown eating disorder.

Ashton Kutcher ended up in the hospital after a month of this diet, which he followed in order to prepare to play Jobs in a biopic.

Fresh fruit and vegetables are both parts of a healthy, balanced diet. But alone, they lack adequate protein and fat, as well as necessary nutrients like vitamin B, calcium, and zinc. That much fructose can also strain your liver and heart.

Around age 50, the actress once called "the most beautiful woman in the world" reportedly tried a diet plan to regain what she felt was her ideal body type by losing weight, but not too much. ("I began to lose my bust! Believe you me, I had to put on some flesh in a hurry," she once famously said of her weight loss.)

The diet was based on meals of her own creation including, most famously, the hamburger and peanut butter sandwich. Other Taylor-made recipes include tuna salad with grapefruit (served in the grapefruit rind for style points) and the Rock Hudson cocktail (Hershey's syrup, vodka, and Kahlua).

Some of Liz's tips are actually part of a healthy diet, like eating less red meat and more fish, fresh fruits, and vegetables. She was also an early champion of the cheat meal (her favorite was fried chicken and chocolate cake), which some research has been shown to help weight loss and promote sustainable dieting.

But her questionable flavor combinations – think steamed cucumbers and mashed potatoes with mint – presumably only "worked" because they were so unappealing to eat.

Macrobiotic foods including whole grains, soy, sea vegetables, and fermented stuff like sauerkraut and miso are the staples of Madonna's diet. She doesn't eat any wheat, eggs, meat, or dairy.

While fermented foods are well-regarded in the medical community for their ability to cultivate your gut flora, this plan is mostly full of downsides. It is not only very restrictive (and therefore probably not sustainable), it also makes it difficult to get enough major nutrients like calcium, iron, and B vitamins.

Kelly Ripa follows a diet plan designed to optimize pH balance with alkaline foods like fruits and vegetables, soy, legumes and nuts. The plan avoids meats, dairy, grains, eggs, meat, processed foods, caffeine, and alcohol.

pH refers to the scale from 0 (acidic, such as battery acid) to 15 (basic, like lye or bleach), with pure water in the middle. But your body naturally works to keep your levels stable, regardless of what you eat, according to the Columbia University's Irving Medical Center, so there's no proof this actually does anything.

The diet is also needlessly restrictive and, to do it properly, you're supposed to test the pH level of your urine regularly. While there are some benefits of the eating plan, they're mostly common-sense, like eating more vegetables and less red meat and junk food. Also coffee has plenty of benefits, so ditching it is not only needlessly hard but not that helpful for most people.

The King of Rock and Roll was well known to have some eccentric eating habits. During his later years, when he struggled with obesity and associated health problems, his doctor recommended he use extra sleep as a means of weight loss. This unknown doctor of ill-repute was even rumored to have gone as far as using a medically-induced coma to help Presley shed some pounds.

The Sleeping Beauty Diet has experienced a resurgence in recent years, according to VICE.

At its most innocuous, this is a version of intermittent fasting. But at its worst, especially cases where drugs like Valium and Xanax are used to stay asleep, sleeping to avoid eating veers into serious eating disorder territory.

Research shows having enough sleep is important for a healthy metabolism, but overdoing it can have the opposite effect and reduce muscle mass.

The grapefruit diet may help you lose weight, but only because of severe calorie restriction, not because of any magical enzyme the fruits contain.

The diet plan limits calories to just 800 a day, comprised of eggs in the morning, grapefruit all day, and a small piece of meat with veggies for dinner.

That kind of undereating can cause you to shed muscle mass, slow your metabolism, and, in severe cases, lead to serious problems due to malnutrition. It can also be dangerous to people already at risk of eating disorders.

That said, grapefruit does have some benefits, like vitamin C and potassium. But it blocks a specific enzyme related to breaking down some drugs, which can mean your body gets a higher dose, so be cautious about mixing it with your meds.

In a 2017 Q&A on Goop.com, a "naturopathic physician" named Linda Lancaster suggested readers drink goat milk and nothing else for eight days straight to get rid of any parasites that might be in the body.

"In those days [biblical times], when a healer learned of a worm infestation, they would put the patient in a tub of milk until the worms would come out to drink—parasites love milk!" Lancaster said.

Not only is this advice lacking evidence, but drinking raw dairy could also lead to foodborne illness and subsequent hospitalization.

Aguilera's diet was based off the 2003 book "7-Day Color Diet" by Jessica Weisel Courtney and Mindy Weisel.

Dieters are told to eat foods in only one color group each day, consuming items that are white, red, green, orange, purple, yellow, and rainbow, in that order. The thinking is that this way of grouping foods ensures dieters get all of their nutrients because different colored foods offer different ones, INSIDER previously reported.

Although limiting yourself to one color each day isn't unhealthy (so long as you eat mainly unprocessed, fresh foods), the same effects can be achieved if a person eats colorful, nutrient-dense meals every day of the week. The diet may be difficult to follow or unsustainable for some people, so eating a simple balanced and rainbow-colored diet daily is fine too.

Pop star Katy Perry reportedly turned to the M-Plan in 2013. Also called the "mushroom diet," it calls for substituting mushrooms for one meal each day — portobellos instead of a burger, for instance.

No one knows who came up with the idea, so you're relying on the collective internet wisdom with this one. Its main claim to fame, that you'll lose weight from so-called "problem areas" of the body, is unproven (experts generally agree it's impossible to spot reduce fat).

However, mushrooms are healthy and swapping them for a meat or pasta can help cut calories and add nutrients like zinc. They might even be good for your brain — some research suggests eating mushrooms can help keep your mind sharp later in life.

Jillette decided he need to lose weight and completely overhaul his lifestyle several years ago after doctors found a 90% blockage in his heart, according to Good Housekeeping.

The choice of potatoes was arbitrary, a sort of mental boot camp for restricting eating habits. "I picked potatoes because it's the funniest word," the 6-foot 7-inch magician told ABC.

Again, a mono diet — eating just one kind of food — doesn't provide the wide range of nutrients your body needs. Jillette said in the ABC interview that he "doesn't respect moderation," but that's exactly what's important in a healthy, balanced diet.

Jillette eventually did transition to a more sustainable, less restrictive diet still based mainly on veggies and whole foods. His weight loss "secret" may be the only one this magician reveals.

The Duchess of Sussex reportedly went on the Dukan diet in order to lose weight quickly after giving birth to her first child. (Buckingham Palace denies this rumor.) The diet is a high-protein and low-carbohydrate plan.

Like the Atkins and ketogenic diets, two other high-protein plans, the Dukan Diet is known for helping dieters lose weight quickly. But the diet is difficult to maintain over time because of its restrictive nature. There are "phases" in place to prevent re-gaining weight after the diet, but it still was ranked 2019's worst diet, according to U.S. News & World Report.

"While the restrictive phases are short, they are very restrictive, so don't underestimate the willpower you'll need," concluded the outlet's analysis of the diet.

The author of "Don Juan" was well known for his flamboyant excess, particularly in his love life. But Lord George Gordon Byron was also fanatic about his appearance, going to great lengths to cultivate the slim, pale look he considered fashionable.

One of those lengths was putting vinegar on everything.

Some people today swear by the health benefits of apple cider vinegar, and a small 2009 study did find consuming vinegar daily led to a small amount of weight loss.

But it's been theorized that Byron was anorexic — he was obsessed losing weight and severely limited his caloric intake.

When he did eat, it was reportedly just hard biscuits, soda water, and vinegar (sometimes with potatoes) to curb his appetite. He died at age 36 from a fever some suspect was the result of his severe weight fluctuations.