A disturbing icon of the impatient, extreme dieter is the procedure to wire the teeth shut so only liquids can get through. While temporary, forcible fasting like this might get results of several pounds in a week, Ayoob warns that people don't often lose fat.
"Whenever you see 'Lose 10 pounds in three days,' can you do it? Yes. Will it be fat? No," Ayoob said.
Instead, most people end up losing water weight, and carbohydrate energy stores known as glycogen. To safely lose fat, and lose it permanently, Ayoob recommends a rate of 2 pounds per week.
"When it comes to weight loss, slow and steady is really going to win the race," Ayoob said.
That's why Dr. Misty Suri at Ochsner Health System Sports Medicine in Jefferson, La., believes patients need to have a long-term, permanent commitment similar to quitting smoking.
"In order to lose weight, people have to want to do it," Suri said. "No amount of 'stop-smoking aid' will work, unless the person is totally committed to it. The same goes for trying to lose weight."
Hence, the final word of warning from the experts: Be suspect if it's not a little difficult, especially if all you have to do is breathe.
Some bad fitness ideas aim to change your mental outlook, others aim to drop your waist, but Ayoob is most wary of any diet idea, including breathing, that is marketed to change your metabolism.
In the mid-'90s, diet books turned to a mishmash of yoga and other meditative breathing exercises as a way to boost your metabolism. The premise was much the same as fanning the flames of a fire: The more oxygen in the body, the more calories it would burn.
"Anything that jump-starts metabolism, that's a red flag," said Ayoob, adding that for most people only exercise can boost metabolism.
But even with exercise plans, Katz said some fitness ideas that incorporate exercise are too easy to be true -- such as yoga to lose weight, or leisurely walking to lose weight.
"There is a book out now on the 'no cardio' diet, advocating against aerobic exercise," Katz said.
The book, "The Cardio-Free Diet" by Jim Karas, expands on the premise that most people don't like to do aerobic exercise and that alternative exercises exist to lose weight.
"But this is a very regrettable position," Katz said. "While it's true that aerobic exercise does not ensure weight loss, it is very important to health -- which this gimmick seems to overlook entirely.
"Gimmicks prevail because we are looking for a way out," Katz said. "There is a native, animal vitality we all have -- and most of us squander. But life is better when it is cultivated -- healthy, vital people have more fun."