Clinically reviewed: 14 August 2026
Glucomannan is a natural, water-soluble dietary fibre supplement available through Morrisons Clinic. It is derived from the root of the konjac plant (also known as elephant yam) and is used to support appetite control and weight management as part of a calorie-controlled diet.
Important: Glucomannan is a fibre-based food supplement. It is not a GLP-1 medication and does not work in the same way as prescription weight loss treatments such as Foundayo, Wegovy, or Mounjaro.
How does Glucomannan work?
Glucomannan works by absorbing water in your stomach, expanding into a thick gel-like substance that creates a feeling of fullness. This can help you eat less by reducing appetite and slowing down how quickly your stomach empties. It has no hormonal or neurological effect on appetite. It works entirely through this physical mechanism.
It is taken as a supplement, typically before meals, and works best when combined with a reduced-calorie diet and healthy lifestyle.
How effective is it?
Glucomannan can support modest weight loss as part of a calorie-controlled diet. Clinical studies typically show weight reductions of around 0.5–2.5kg over a period of 4–12 weeks when taken consistently. It is not comparable in effectiveness to prescription GLP-1 medications, which are clinically evidenced to support significantly greater weight loss.
Glucomannan is best suited to individuals who are looking for a non-prescription supplement to support their dietary efforts, rather than a medical treatment programme.
How is Glucomannan different from Foundayo or other GLP-1 treatments?
These are fundamentally different products:
Glucomannan is a food supplement derived from a natural plant fibre. It does not require a prescription and works by creating physical fullness in the stomach.
Foundayo (and other GLP-1 medications such as Wegovy or Mounjaro) are prescription medications. They work hormonally, mimicking gut hormones to reduce appetite at a neurological level, and are associated with substantially greater weight loss over time.
If you are looking for a prescription GLP-1 treatment, please see our information on Foundayo. Glucomannan is not a substitute for GLP-1 treatment.
Frequently asked questions
Is Glucomannan a GLP-1?
No. Glucomannan is a natural fibre supplement and is not a GLP-1 medication. It works differently to Foundayo or other GLP-1 treatments and does not have a hormonal effect on appetite.
Do I need a prescription for Glucomannan?
No. Glucomannan is a food supplement, not a prescription medication. However, you will need to complete a consultation form before it can be supplied through Morrisons Clinic.
Can I use a discount code for Glucomannan?
No — Glucomannan is excluded from all current promotional offers and discount codes.
Is Glucomannan safe to take?
Glucomannan is generally well tolerated when taken as directed with plenty of water. As with any supplement, if you have an existing medical condition or take other medications, please consult your GP or a clinician before starting. You should always take it with a full glass of water.
Will Glucomannan give the same results as a GLP-1 medication?
No. Glucomannan is a supplement that provides modest support for weight management. GLP-1 medications such as Foundayo are prescription treatments with significantly greater clinical evidence for weight loss. If you are considering a GLP-1 treatment, please see our Foundayo information page.