In addition to the numerous health benefits, eating lots of fiber-rich foods (like shirataki noodles) can help you lose weight. Fiber itself has no calories and is passed through your digestive system intact. However, because fiber absorbs water, it provides a "full" feeling. For example, eating an apple (which is rich in fiber) is more filling than drinking 4 ounces of apple juice, even though both forms contain an identical number of calories. Foods high in fiber also often require more chewing, which makes it more difficult for you to consume a large number of calories in a short period of time.
Some evidence suggests that glucomannan in any form may help weight loss, since it absorbs a lot of water and occupies space in your stomach, which leads to the feeling of being full. In one study, where obese adults were given one gram of glucomannan with a cup of water one hour before each meal for eight weeks, average weight loss was reported to be 5.5 pounds (source). In another study, healthy men were given 3.9 grams of glucomannan daily for four weeks, which resulted in decreased total cholesterol, systolic blood pressure, low-density lipoprotein and triglycerides (Source).
It is even an accepted fact at a European level, as according to the Commission Regulation No 432/2012 of the European Union, glucomannan aids weight loss as well as keeping blood cholesterol concentrations at normal levels if taken in the amount of 4 gr a day, in three portions of 1 gr each minimum. It is important to take it with plenty of water to ensure the substance reaches stomach.