glucomannan fibre ok to use for weight loss?

flannelette

Hi - has anyone here, needing to lose weight, besides exercising tried using a fibre called glucomannan? It's available in Canada through a company called FemMed. Probably a similar one in the US? Taken with water, it apparently gives feelings of fullness so you're not eating so often or much. I won't try any supplements without first investigating them.....in case they are not a good idea for people with bc, and mine PR+ and ER+. thanks for suggestions/advice.