Red chilli peppers in a bag (Corbis)

So, all those diet and weight-loss fads you see everywhere? Well, they're usually called fads for a reason, says Michael Jay Nusbaum, M.D., founder of The Obesity Treatment Centers of New Jersey—meaning they may not be based on much at all in terms of research and will burn out in no time.

He says these are some of his favorite fads to which he'd like to say sayonara.

1: Spicy foods help you burn fat. "This idea may have come out of a report about capsaicin causing sweat glands to become stimulated," Dr. Nusbaum says. "Clearly, that one is true, as those five-alarm buffalo wings made me sweat the last time I had them—and it was great. But I didn't lose any weight from it, and neither will you."

2: Colon cleansing. According to Dr. Nusbaum, there's a lot of misinformation about this one circulating out there. "The colon is part of the gastrointestinal tract, which is really just a continuous tube," he says. "What you put in your mouth goes through this tube. What your body wants, it absorbs from this tube. What it does not want comes out the other end. So, unless you're really, really constipated, you will not lose weight from colon cleansing (other than water loss from potential dehydration)."

3: Acai pills for weight loss. "No-peer reviewed studies have ever provend that acai berries do anything more than increase your antioxidant intake," Dr. Nusbaum says. So, while they do have some nutritional value, Dr. Nusbaum says there's no evidence they'll actually help boost weight loss.

4: The Beta hCG (human chorionic gonadotropin) Diet. This unapproved-by-the-FDA diet plan requires eight weeks of eating 500 calories a day, plus getting shots or taking pills filled with hCG. "I can't begin to tell you how bad this one is," Dr. Nusbaum says. "A bad study came out years ago—by a questionable source—saying that beta hCG can preserve muscle mass in the face of starvation. A starvation diet of 500 calories per day is just plain dangerous (and using anything to make it sound OK is equally as dangerous). Besides, before you decide to do this one, find out where that beta hCG from. It will make your stomach turn." (Spoiler: hCG is the hormone secreted by human embryos—though there are synthetic versions too.)

5: Skipping breakfast and lunch and then eating just one big meal for dinner promotes weight loss. Nope, says Dr. Nusbaum. "This one just forces your body into starvation mode, slows your metabolism down, makes you feel sluggish, and actually causes you to gain weight."

So what do you think?