November 23, 2022

Can Glucomannan Help With Weight Loss | Scientific Studies and Research

by Bryan Wellington

Numbers recently reported by NBC News show that 17% of Americans are on some sort of diet. And that number has been climbing. It’s no surprise that with millions of people trying to lose weight, some number of them have turned to dietary supplements.

Finding the right supplements, however, can be tricky. It’s important to rely on actual science instead of fads. I’ve found a number of studies that have broken down what weight loss–or weight gain–was observed in real people using Glucomannan fiber.

Key Findings

✲ Majority of studies found that Glucomannan helped reduce total weight.

✲ One study conspicuously did not support those findings.

✲ All successes were reported in already overweight individuals; not all weight loss was associated with fat loss.

✲ No adverse reactions or side effects were reported.

Successful Studies

There are dozens of clinical studies and trials involving Glucomannan. The ones I’ve pulled from the literature offer a diversity of study designs, giving a larger picture of the successful studies than simply pulling one or two.

No-Change in Lifestyle Study

An interesting study was published in the International Journal of Obesity wherein participants were instructed to not change any of their diet or exercise behavior while they took Glucomannan prior to meals. 

All of the participants were obese, and the average weight loss was 5.5 pounds over eight weeks. No measurements on body fat percentages are available.

Diet and Glucomannan

Another study was conducted with three different types of commercially available fiber supplements, this time including exercise. Two of the fiber groups included Glucomannan, and the average weight loss was roughly 1.8 pounds per week per person. These results indicate, to little surprise, that including diet and exercise increased the weight loss benefits of Glucomannan.

One important note from this study is the large sample size–over 150 people. In scientific studies, the larger the sample size the more reliable the results.

Outlier–Non-Successful Study

It’s always important to include any evidence of a supplement not working. In the case of Glucomannan I could find only one–but it is significant for the two difference between it and the previous studies.

The successful studies on Glucomannan and weight loss–the two above and dozens of others–focused on either obese persons who were not dieting or who were not exercising. In some cases they used participants who did neither.

In a study from the Journal Obesity, 53 participants were recruited, and randomly assigned to the test or placebo groups. In the end, there was no difference between the two groups on body mass or weight.

The differences in this study, however, are that these participants–both the placebo and the test group–were already dieting and exercising.

I include this study in the review because it may indicate that in healthy, currently dieting and exercising adults, the addition of Glucomannan does not appear to move the needle more than keeping on with present behaviors. But in other groups, where there is no diet and exercising, starting those behaviors along with Glucomannan does move the needle more than those behaviors alone.

This may suggest that the participants in the non-successful study already had high-fiber diets, or that people not dieting or exercising are more sensitive to the addition of fiber.

Review of the Whole Body of Literature

Lastly, to check our work so to speak, we find a literature review including six different studies that show significant weight loss benefits to Glucomannan. There was a higher degree of weight loss in women than in men, but both groups saw positive results, and no adverse effects were reported.


Consumers have many options when it comes to dietary supplements. The two most important considerations are: does the supplement work? And is the supplement safe?

In the case of Glucomannan we have substantial scientific evidence that this supplement can help with weight loss, and does not have any known side effects.


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