Does Glucosamine Make You Gain Weight? What the Trials Show

No. Glucosamine does not make you gain weight. In the human trials, which followed people for up to three years, weight gain never appeared as a side effect, and side effects on glucosamine were no more common than on placebo.^{1, 2, 3} The idea comes from rats and mice given glucosamine by infusion or in their drinking water at doses hundreds of times higher than any supplement, where it disturbed insulin signalling and, in one 2015 mouse study, increased weight gain.^{4, 5} Glucosamine is a sugar-like molecule, but a day's dose supplies about 6 kcal, and it does not hold water, change appetite or cause weight loss. What moves the scales for people with sore joints is how much they move: pain makes people sit more, and the NHS's first advice for osteoarthritis is exercise and, where needed, weight loss.⁶

Sources checked on 30 October 2026.

• Weight gain: not seen in human trials; the claim traces to rodent studies at very high doses
• Calories: about 6 kcal a day, less than half a teaspoon of sugar
• Bloating and water retention: no evidence; side effects in trials matched placebo
• Blood sugar: no change in HbA1c or fasting glucose in trials, including in type 2 diabetes

Does glucosamine make you gain weight?

No. Glucosamine has been tested in large, long randomised trials: 1,583 people for six months in the US GAIT trial, and 212 and 202 people for three years in two European trials of glucosamine sulphate.^{1, 2, 3} Those trials recorded every adverse event, and weight gain was not among them: in the three-year trials safety was no different from placebo, and in GAIT adverse events were mild, infrequent and evenly spread across the groups. The Cochrane review of 20 trials put the risk of an adverse reaction on glucosamine at 0.97 times placebo.⁷ If 1,500 mg a day shifted weight, three years of follow-up in 400 people would have shown it.

Where the weight-gain idea comes from

From animals, not people. Glucosamine feeds into the hexosamine pathway, one of the routes a cell uses to sense how much nutrient is around. Large doses of glucosamine infused into animals altered glucose metabolism, and the cell studies behind the worry used concentrations 100 to 200 times higher than the tissue levels oral glucosamine produces in a person.⁴ In 2015, a mouse study gave animals a 10% glucosamine solution as their drinking water: mice on a normal diet gained more weight and body fat than controls, while mice on a high-fat diet gained less.⁵ Its first half is where the claim comes from.

It does not transfer to a person taking capsules. The dose is several hundred times higher for body weight, and when the question was put to people, nothing happened: forty lean and obese adults took 500 mg three times a day for six weeks in a crossover trial measured with the insulin clamp, and it neither caused insulin resistance nor worsened it.⁸

Can glucosamine cause bloating or water retention?

There is no evidence that glucosamine makes the body hold water. Adverse reactions were no more common on glucosamine than on placebo, and in the 90-day diabetes trial below one person stopped because of wind, which can feel like bloating but is not fluid.^{7, 9} Glucosamine sulphate is sold stabilised with a salt, and the crystalline product used in the European trials carries sodium chloride: about 150 mg of sodium a day, roughly 6% of the NHS adult salt limit.¹³ The potassium-chloride form carries none.

Does glucosamine affect blood sugar?

Not at supplement doses, on the trial evidence. In a 90-day randomised trial in people with type 2 diabetes, glucosamine with chondroitin did not change HbA1c, the three-month average of blood glucose, and nobody needed a change to their diabetes treatment.⁹ A 2011 systematic review of eleven human studies called the picture mixed, because a few small studies in people with impaired glucose tolerance recorded a dip in insulin sensitivity; a review the same year of the long-term trials, up to three years and including people with diabetes, concluded that glucosamine has no effect on fasting glucose or insulin sensitivity at any oral dose.^{10, 11} If you have diabetes you can take glucosamine; checking your readings in the first few weeks is sensible.

Does glucosamine affect appetite or cause weight loss?

No to both. No trial has recorded a change in appetite, and glucosamine is not a weight-loss supplement; the mice that gained less on it were obese mice on a high-fat diet drinking a dose no person takes.⁵

What does change your weight when your joints hurt?

Movement, or the lack of it. Knee or hip pain makes people move less. It runs the other way too: the NHS says being overweight often makes osteoarthritis worse by putting extra strain on joints, which is why it puts exercise and, for people who are overweight, weight loss at the top of its osteoarthritis treatments.⁶ Exercise that builds the muscles around a sore joint usually eases symptoms rather than worsening them; how can I naturally lubricate my joints covers what movement does for a joint.

What glucosamine does and does not do

Glucosamine is an amino sugar taken for knee and hip osteoarthritis. The 2010 network meta-analysis of ten large trials found an average effect on pain too small to be clinically relevant, while the Cochrane review found that glucosamine sulphate, in the preparation most of the positive trials used at 1,500 mg a day, improved pain and function against placebo, and individual response varies more than the averages suggest.^{7, 12} UK guidance does not recommend it on the NHS, and in the UK it has been sold both as a licensed medicine for knee osteoarthritis and as a food supplement with no authorised health claim.^{6, 14} The fair test is three months daily, then stop if nothing has changed; is glucosamine bad for you covers who should ask first. The Wellgard joint health guide sets out the trials.

What we don't know

• Long-term effects in diabetes and obesity: the insulin clamp trial lasted six weeks and the HbA1c trial 90 days.^{8, 9}
• Impaired glucose tolerance: the few small studies are mixed, and no definitive long-term study exists.^{10, 11}

Frequently asked questions

Does glucosamine chondroitin, or chondroitin on its own, cause weight gain?

No. GAIT gave the combination to over 300 people for six months, with adverse events mild and evenly spread, and the diabetes trial above used it for 90 days with wind the only reaction reported; neither reported weight gain.^{1, 9}

What are the symptoms of too much glucosamine?

No toxic dose has been established in humans; in animals, 2,700 mg per kilogram a day for a year caused no adverse effects.⁴

Does glucosamine make you sleepy?

Drowsiness is not a recognised effect: across the placebo-controlled trials, adverse reactions were no more frequent on glucosamine than on placebo.⁷ If you feel drowsy after starting it, stop and see whether it passes.

Does glucosamine cause hair loss?

No trial or case series links glucosamine to hair loss. The NHS lists illness, stress, weight loss and iron deficiency among the causes of temporary hair loss; a GP can usually tell the cause.¹⁵

Sources

1. Clegg DO, et al. Glucosamine, chondroitin sulfate, and the two in combination for painful knee osteoarthritis. New England Journal of Medicine, 2006. Randomised placebo-controlled trial, 1,583 people, 24 weeks; NIH-funded. PubMed 16495392.
2. Reginster JY, et al. Long-term effects of glucosamine sulphate on osteoarthritis progression: a randomised, placebo-controlled clinical trial. Lancet, 2001. Randomised placebo-controlled trial, 212 people, 3 years; funding not stated on PubMed. PubMed 11214126.
3. Pavelka K, et al. Glucosamine sulfate use and delay of progression of knee osteoarthritis: a 3-year, randomized, placebo-controlled, double-blind study. Archives of Internal Medicine, 2002. Randomised placebo-controlled trial, 202 people, 3 years; funding not stated on PubMed. PubMed 12374520.
4. Anderson JW, et al. Glucosamine effects in humans: a review. Food and Chemical Toxicology, 2005. Review of animal data and human trials in 3,063 people; funding not stated on PubMed. PubMed 15621331.
5. Hwang JS, et al. Glucosamine and weight gain in mice fed chow or high-fat diets. Metabolism, 2015. Mouse and cell study; funding not stated on PubMed. PubMed 25516476.
6. NHS. Osteoarthritis: treatment. Page last reviewed 20 March 2023 (review overdue). nhs.uk/conditions/osteoarthritis/treatment.
7. Towheed TE, et al. Glucosamine therapy for treating osteoarthritis. Cochrane Database of Systematic Reviews, 2005. Cochrane systematic review, 20 trials, 2,570 people; one author held patents on glucosamine-type compounds. PubMed 15846645.
8. Muniyappa R, et al. Oral glucosamine for 6 weeks does not cause or worsen insulin resistance in lean or obese subjects. Diabetes, 2006. Randomised placebo-controlled crossover trial, 40 adults, 6 weeks per arm; NIH-funded. PubMed 17065354.
9. Scroggie DA, et al. The effect of glucosamine-chondroitin supplementation on glycosylated hemoglobin levels in patients with type 2 diabetes mellitus. Archives of Internal Medicine, 2003. Randomised placebo-controlled trial in people with type 2 diabetes, 90 days; size not given in the abstract; US government funding. PubMed 12860582.
10. Dostrovsky NR, et al. The effect of glucosamine on glucose metabolism in humans: a systematic review of the literature. Osteoarthritis and Cartilage, 2011. Systematic review, 11 studies; funding not stated on PubMed. PubMed 21251987.
11. Simon RR, et al. A comprehensive review of oral glucosamine use and effects on glucose metabolism in normal and diabetic individuals. Diabetes/Metabolism Research and Reviews, 2011. Narrative review; funding not stated on PubMed. PubMed 21218504.
12. Wandel S, et al. Effects of glucosamine, chondroitin, or placebo in patients with osteoarthritis of hip or knee: network meta-analysis. BMJ, 2010. Network meta-analysis, 10 trials, 3,803 people; Medical Research Council funding. PubMed 20847017.
13. NHS. Salt: the facts. Page last reviewed 17 April 2023. nhs.uk.
14. MHRA. Change in the classification of certain glucosamine products. News story, 5 September 2018. gov.uk.
15. NHS. Hair loss. Page last reviewed 24 January 2024. nhs.uk.

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This article is general information, not medical advice. Joint pain with swelling or heat, or pain after an injury, needs a GP, and if you have diabetes or take warfarin, speak to your GP or pharmacist before starting glucosamine.