The Kardashians are “obsessed.” Jessica Alba claims it helped her return to her pre-baby body. But what exactly is “waist training,” and does it work? More importantly, is it safe?

Losing weight is hard, especially when you want to lose it fast. Lowering the calorie intake, reading nutrition labels for deceptive ingredients, exercising - it just takes too much effort and time.

So of course, when everyone hear about something that guarantees a slimmer midsection in a few weeks without much effort, everybody wants to give it a try.

Enter waist training: wearing a corset-like contraption to cinch the core, hips, and back. The idea is to wear it for a certain amount of time every day, and eventually, the body "molds" itself into a slimmer figure.

Now to the big question: Should you try it?

Dr. Sherry Ross, OB/GYN at Providence Saint John’s Health Center in Santa Monica, California gives the scoop on Hollywood’s latest must-have accessory: a modern-day corset.

“If it is tied too tightly, there can be rib fractures and it can affect your breathing,” Sherry told HollywoodLife exclusively. “It can affect your abdominal muscles and posture, especially if you wear it while working out."

"It actually immobilizes your abdominal muscles, so you are not allowing these muscles to be worked on, and it can weaken them. I do not think it can affect your organs, but it is the ribs, abdominal muscles and lungs could be affected if it is really tight. Restrict your ability to breathe,” she added.

Famous sisters Khloe Kardashian and Kylie Jenner have fueled plenty of interest in this trend, by posting Instagram photos of themselves in recent months wearing waist trainers, bands of material that wrap tightly around the waist and lower rib cage to provide an instantly slimming, hourglass look.

Dr. Sherry insists that celebs are a bit misleading in making people think it actually reduces the size of your waist.

“As soon as you remove it, your waist goes back to where it was. It is more an emotional effect when you are wearing it because you feel better about yourself. It is a misconception that it is going to effect you losing inches off your abdominal area,” she said.

“There are claims that when you wear a Waist Trainer it increases thermal activity, which triggers fat loss, but this was not proven. It feels good to wear it, but it is not doing anything to help you lose weight.”

Some people can get away with wearing the waist trainer without any real harm done. But for a real, long-term weight-loss plan, you're better off looking elsewhere.