Direct answer: A glucomannan product may use the authorised GB weight-loss claim only when it contains 1g per quantified portion and explains the full protocol: 3g daily as three 1g doses, each with 1–2 glasses of water before meals, in the context of an energy-restricted diet.
Commercial disclosure: We sell two products containing glucomannan. This guide separates the legal claim conditions from our product comparison.
The authorised wording
“Glucomannan in the context of an energy-restricted diet contributes to weight loss.”
That sentence is only the headline. The conditions of use determine whether a particular product and its directions can carry it.
The five conditions a label must account for
| Condition | What it means when shopping |
|---|---|
| 1g per quantified portion | Check the amount in the actual capsule serving or measured scoop. |
| 3g each day | The product directions must make the daily total achievable. |
| Three separate 1g doses | One large daily dose is not the authorised protocol. |
| Water before meals | Each dose is taken with 1–2 glasses of water before a meal. |
| Energy-restricted diet | The claim applies alongside a diet supplying less energy than is used. |
Why “3g a day” is not the whole answer
Two products can both advertise 3g while giving different instructions. A single 3g serving does not match the claim’s three-portion protocol. A product that declares 500mg per capsule needs two capsules per portion and six capsules across the day to provide three 1g portions.
This makes the directions as important as the front-of-pack number.
What does “energy-restricted diet” mean?
It means the overall diet supplies less energy than the body uses. The authorised wording does not permit a seller to present glucomannan as a substitute for that diet, or to imply that diet and activity are unnecessary.
For general weight-management guidance, use an evidence-based plan such as the NHS weight-loss resources. A supplement page should not promise a particular rate or amount of loss; such claims are prohibited for foods and supplements.
What may not be substituted for the claim?
- “Suppresses appetite”
- “Stops cravings”
- “Keeps you full all day”
- “Fat burner”
- “Speeds up metabolism”
- Any promised number of kilograms, clothing sizes or time to lose weight
Those phrases do not become acceptable merely because the product also contains glucomannan. Claims for foods and supplements must remain compatible with authorised wording and its conditions.
What about the cholesterol claim?
Glucomannan also has a separate authorised claim for the maintenance of normal blood cholesterol levels. The beneficial effect is obtained with 4g daily. This is a different claim with a different intake condition; eligibility for the weight claim does not automatically establish eligibility for the cholesterol claim.
The safety condition
The claim conditions require a choking warning for people with swallowing difficulties or when the fibre is taken with inadequate fluid, plus advice to take it with plenty of water so it reaches the stomach.
Do not take glucomannan if you have swallowing difficulties. Never take the powder dry. Follow the product’s exact water instructions and ask a pharmacist about timing if you take medicines.
How our two products fit
Konjac Thermogenic Shred provides 1,000mg per serving. Three servings, taken as directed before meals with water, supply the three 1g portions used in the claim.
Fibre&More provides 1.05g per 5g serving within a broader high-fibre powder. Three servings supply 3.15g, but the product’s total fibre blend, measuring directions and water instructions still need to be considered.
Neither product changes the energy-restricted-diet condition.
Frequently asked questions
Can I take all 3g at once?
That does not match the authorised weight-claim protocol, which specifies three 1g doses before meals.
Does 1,000mg mean 1g?
Yes. 1,000mg equals 1g. Always check whether the amount is per capsule, per serving or per daily dose.
Is the warning optional for powders?
No. The choking and adequate-fluid requirement is tied to the claim conditions, regardless of whether the product is a powder, capsule or tablet.
Sources and review method
Claim wording and conditions were checked on 2 August 2026 against the GB Nutrition and Health Claims Register, the authorising regulation, GOV.UK compliance guidance and CAP guidance.
Next: learn what glucomannan is or compare products in our UK glucomannan buyer’s guide.
Written by Barry Lees. Last reviewed 2 August 2026. Always read the label. Food supplements are not a substitute for a varied and balanced diet and a healthy lifestyle.
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