While mass obesity might be a more recent historical phenomenon, the practice of using weird diets to achieve the perfect body shape has been around for centuries.

Here are seven weird ways we suggest you don’t try to lose weight:

1. Master Cleanse

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Invented in the ‘40s as a means of “cleansing” the body of toxic chemicals, this diet involves ingesting nothing but a cocktail of water, lemon juice, cayenne pepper and maple syrup for four to 14 days, according to a Cornell University course blog.

Obviously, negative health effects abound with this diet, as the body is not receiving a wide variety of essential nutrients. That hasn’t stopped celebrities such as Beyonce, Ashton Kutcher, and Demi Moore from promoting it, however.

2. Tapeworm diet

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For the truly desperate. As you might have guessed, this diet involves intentionally contracting a tapeworm, a parasitic worm – which can grow up to 12 feet – that attaches itself to the host’s intestines and absorbs nutrients passing by it, according to Medline Plus.

There’s evidence of tapeworm pills being sold in the U.S. early 20th century as a diet, although it’s not certain whether they were real or just a snake oil cure. However the weird diet has surfaced in recent years, perhaps because of the Internet, appearing in faraway places such as Hong Kong – and Iowa.

3. The blood type diet

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This weird diet dictates that you only eat certain foods and avoid others, based on your blood type, according to WebMD.

For instance, the blood type O (o for “old”) retains memories of ancient times, so anyone with type O blood should eat lean meats and fish while avoiding grains and bread. Type A (for agrarian), however, should focus on soy proteins and organic vegetables.

While nutritionists say there are good, individual recommendations within the diet, there is no scientific basis for the correlation between blood type and digestion, according to Reuters.

4. Prayer dieting

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It’s a real thing. Quoting directly from an advocacy website:

“Guide me lord, as I strive to lose weight. You are my light and my anchor, and with you I know all things are possible. Help me this day to make healthy choices and give me the strength to fight against destructive cravings that negatively affect my health.”

To its credit, the website encourages supplicants to not “fall for easy-outs and false prophets” like diet pills, and instead work on eating right and exercising.

5. Paleo diet

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Once upon a time, humans lived off the land, hunting for meat and foraging for nuts and berries. Now, as our modern diet has reached its apex of ramen burgers and donut bacon sandwiches, some people are trying to go back to those antediluvian glory days.

Named after the Paleolithic period, which ended roughly 10,000 years ago, it aims to emulate the meals of our cavemen ancestors.

However, while avoiding processed and fatty foods is all good and well, the diet is based on simplistic assumptions about our ancestors, and it introduces limitations on foods like whole grains, beans, and low-fat dairy, which can cause nutritional imbalances, according to WebMD.

6. The Great Masticator’s chewing diet

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Arguing that not chewing one’s food properly was the main cause of overeating and poor health, early 20th century diet luminary Horace Fletcher – aka “The Great Masticator” – promoted chewing each bit of food at least 32 times, according to the U.S. National Library of Medicine.

Ideally, one should eat until the “food swallowed itself.”

Given that this would probably render every morsel into a flavorless gruel, the diet probably did have its intended effect on overeating, and was adopted by luminaries of the time such as Upton Sinclair, John D. Rockefeller, and Thomas Edison, according to National Public Radio.

7. Cotton ball diet

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The greatest weight loss technique of all, of course, is simply not eating. But what do you do when that pesky stomach pain starts acting up again? Why, just eat a cotton ball, of course (dipping in orange juice is optional)!

Adopted by several famous young models, according to the Huffington Post, this weird diet fad has been universally condemned by nutritionists as one of the stupidest things you could ever do to lose weight.

Not only are the cotton balls quite obviously free of any nutritional value, they could also contain chemicals such as dioxins that are potentially very dangerous.

Updated