A lot of people need to lose weight.
Unfortunately, it is not always easy to achieve and long-term success is rare. All sorts of things are claimed to help with this… diets, potions and pills that are supposed to make things easier. One of them is called glucomannan, a natural dietary fiber that is claimed to be an effective weight-loss supplement. This article takes a detailed look at the science behind glucomannan and whether it is something you should be taking.
What is Glucomannan?
Glucomannan is a natural, water-soluble dietary fiber extracted from the roots of the elephant yam, also known as konjac. It is available as a supplement, in drink mixes and is also added to food products, such as pasta and flour. It is also the main ingredient in shirataki noodles. Glucomannan comprises 40% of the dry weight of the elephant yam, which is originally from Southeast Asia. It has a long history of use in herbal mixtures and traditional foods like tofu, noodles, and konjac jelly.
In addition to being sold as a dietary supplement, it is used as a food additive, specifically as an emulsifier and thickener denoted with the E-number E425-ii. Glucomannan has an exceptional ability to absorb water and is one of the most viscous dietary fibers known. It absorbs so much liquid that if you empty a glucomannan capsule into a small glass of water, the entire thing turns into a gel. These unique properties are believed to mediate its effects on weight loss.
Like other soluble fibers, it is believed to promote weight loss via several mechanisms (1):
- It has a very low calorie content.
- It takes up space in the stomach and promotes a feeling of fullness (satiety), reducing food intake at a subsequent meal.
- It delays emptying of the stomach, contributing to increased satiety (2).
- Like other soluble fibers, it reduces the absorption of protein and fat (3).
It also feeds the friendly bacteria in the intestine, which turn it into short-chain fatty acids like butyrate, shown to protect against fat gain in some animal studies (4, 5). Feeding the friendly gut bacteria may also have other benefits, and some studies have shown a correlation between altered gut bacteria and body weight (6, 7). These mechanisms are believed to be similar to the effects of other soluble fibers on weight loss. However, glucomannan is different from other soluble fibers due to it being even more viscous, which makes it particularly effective.