Some people take their quest to be lean to the extreme. 

Take Derek Nance, for one. The Kentucky man told Vice Magazine that he’s been eating nothing but raw meat from animals he’s slaughtered for the past five years. He now keeps a severed goat head in his freezer, but it all began as a way to solve his chronic nausea and vomiting. Now he says he’s feeling great. 

His diet is a spinoff of the Paleo diet and is also based on the research of Weston Prince, a dentist from the 1930s who found that Native Americans who survived on a “guts-and-grease” diet were healthier than modern Americans. 

And Nance isn’t anywhere near the top of the strangest diets list. Here are five more bizarre food regimens real people have actually tried.

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Breatharianism: Eating Like a Plant

A 65-year-old British transplant living in Seattle, Wash. recently attempted to live for 100 days solely on air, tea, water, and sunlight. This spiritual practice, called "breatharianism," has reportedly killed five people since the 1990s. 

The woman—appropriately named Naveena Shine—only made it 48 days before calling it quits and is slowly going back to solid foods. 

Was it because she wanted to avoid a slow death by starvation? Nope. She says she decided to stop and go back to work because she couldn’t afford to pay her bills. 

Symbiotic Algae Masks

Michael Burton and Michiko Nitta have found a way to give plants and humans a truly symbiotic relationship.

Their “Algae Opera” project debuted last year when an opera singer performed with their specially designed mask on. Her deep, gaping breaths fueled algae growth inside the mask's many plastic tubes.

The microscopic plants fed on the carbon dioxide she exhaled, and those in attendance were invited to drink the nutritious green sludge she produced. 

While there have been no reported sightings of people wearing these masks in public, don't be too alarmed if you spot one. 

Cotton Balls for Breakfast

One crash diet some professional models use to stay rail thin involves eating cotton balls dipped in orange juice. It helps fill their stomachs and prevents hunger but contains very few calories, Bria Murphy, daughter of comedian Eddie Murphy, told Good Morning America

Cotton balls are not a food item, and being thin enough to show off your ribcage on the run way isn't a healthy aspiration. 

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‘Soylent’ Is (for) People! 

Rob Rhinehart saw the need for innovation in the food system and set out to invent it. 

Earlier this year, the 24-year-old software engineer raised $800,000 to mass-produce Soylent, a foodstuff that shares its name with Soylent Green, the infamous fictitious food rations made from the remains of people. 

Soylent is a powdered mix of carbs, proteins, fats, vitamins, and minerals. Rhinehart says his powder can power a human indefinitely, but as with all things, only time will tell. He says he's eaten nothing but soylent for months with no ill health effects.  

Rhinehart claims Soylent could help people with severe food allergies, indigestion, and other food-related illnesses.

Cheese Only, Please

Some diets aren’t fueled by the desire for good looks. Some are based on fear.  

Dave Nunely ate 225 pounds of cheddar cheese a year, and not because he was on some man-versus-food adventure. He said it’s the only thing he’s liked to eat for his entire 29 years on the planet. 

The though of a hot meal makes his stomach turn. He’s so picky, in fact, that his cheese must be grated. Nunely—who is from England, not Wisconsin—was the focus of a BBC program, Freaky Eaters.

The last word on Nunely was that he was eventually able to eat some chips and a form of oatmeal. Gouda for him.