Crash diets, like the five-bite diet, only give you temporary results, Dr. Julianne Barry, a general practitioner at London Doctors Clinic, told Cosmopolitan UK. One of the major reasons this diet doesn't work is because a healthy metabolism is a major factor in weight management, and crash diets actually slow down your metabolism.

"Muscle breakdown is much greater with extreme dieting," Dr. Barry explains. "Less muscle reduces your metabolic rate, which is the number of calories you burn while resting." So, on top of not burning as many calories when you're at rest, your metabolism won't speed up once you start eating normally again, either.

Carly Fraser, owner and founder of the health website Live Love Fruit, wrote on her blog that she had unknowingly restricted too much when she started a new diet and is still struggling with getting her metabolism back to normal.

The problem, Fraser explains, is that diets like the five-bite diet put your body into starvation mode, which can lower your metabolism, affect your ability to regulate temperature, and potentially damage your organs, per NPR.

But these aren't the only reasons you need to steer clear of the five-bite diet.