What is the best magnesium supplement for weight loss in the UK?

What magnesium does not do

Askari's 2021 meta-analysis of randomised trials found no meaningful effect of magnesium supplementation on body weight or waist circumference across the pooled studies. The laxative effect of citrate or oxide moves water and stool, which shows on the scales for a day and means nothing. No weight loss claim is authorised for magnesium in the UK, and a product marketed that way is telling you how it operates.

What magnesium does do on a cut

The authorised claims describe the useful part. Magnesium contributes to normal energy-yielding metabolism, normal muscle function, normal protein synthesis and a reduction of tiredness and fatigue. On a cut you are eating less food, which means less magnesium from food, while training and sweating as much as ever. Nielsen and Lukaski's review documents rising losses with training load; Zhang's 2017 review found supplementation helped performance where intake was low. A cut is exactly the situation where intake drifts low, so the case for keeping magnesium at the reference level is stronger, not weaker, when you are dieting.

Two practical points. A capsule has no calories, so it costs nothing on the plan. And sleep tends to suffer on a deficit; the small sleep trials with magnesium ran at 500mg a day, so a 300mg evening dose is a reasonable, cheap thing to keep in place.

Which magnesium for a cutting phase

Glycinate. Citrate's laxative effect is the last thing you want when food is low and the gut is already unsettled, and oxide is barely absorbed. The worked example is Futuro Labs Magnesium Glycinate: 2 capsules give 1500mg bisglycinate at 20%, 300mg elemental, 80% NRV, vegan capsules, made in the UK under GMP and BRC, independently tested for heavy metals, 180 capsules for £19.99, so 22p a day. The best magnesium supplement for weight loss in the UK is not a weight loss supplement at all; it is the 300mg elemental one you keep taking while the diet does the work.

How do you fit magnesium into a cut without adding calories or bloat?

Two capsules with the evening meal, and that is the whole routine. A vegan capsule of magnesium bisglycinate has no sugar and no calories, so it costs nothing on the plan. It does not interact with creatine, caffeine or protein, so there is no need to separate it from a pre-workout or a shake. The bloat question is about form: citrate and oxide pull water into the bowel and can leave you feeling puffy and running to the loo, which is the opposite of what you want when you are trying to look lean; chelated glycinate does not. Keep zinc modest if you stack it, because zinc competes with magnesium only at high doses, and keep sodium and fluid up on training days, because cramps and flat sessions on a cut are more often an electrolyte balance problem than a magnesium one.

What to check on the label

Questions people also ask

Does magnesium help you lose weight?

No. A 2021 meta-analysis of randomised trials found no meaningful effect on body weight. It supports normal energy metabolism and muscle function while you diet, which is a different thing.

Does magnesium citrate make you lose weight?

It can loosen the bowel, which drops a little water and stool weight for a day. That is not fat loss.

Which magnesium is best for belly fat?

None. No form of magnesium reduces body fat. Pick glycinate for the intake and let the deficit do the rest.

Is magnesium good for a cutting diet?

Yes, for the boring reasons: less food means less magnesium, training losses continue, and low intake shows up as fatigue and poor sleep. 300mg elemental a day keeps that covered.

Should I take magnesium in the morning or at night when cutting?

Evening, with food. Sleep is usually the first thing to slip on a diet and the sleep trials dosed in the evening.

Sources

1. Futuro Labs Magnesium Glycinate listing, Amazon UK, label and price checked 31 August 2026. https://www.amazon.co.uk/dp/B0BT7Z5VQW
2. Askari M, et al. The effects of magnesium supplementation on obesity measures in adults: a systematic review and dose-response meta-analysis of randomized controlled trials. Critical Reviews in Food Science and Nutrition 2021;61(17):2921-2937. PubMed record
3. EFSA Panel on Dietetic Products, Nutrition and Allergies. Scientific Opinion on the substantiation of health claims related to magnesium. EFSA Journal 2010;8(10):1807. https://efsa.onlinelibrary.wiley.com/doi/10.2903/j.efsa.2010.1807
4. Nielsen FH, Lukaski HC. Update on the relationship between magnesium and exercise. Magnesium Research 2006;19(3):180-189. PubMed record
5. Zhang Y, Xun P, Wang R, Mao L, He K. Can magnesium enhance exercise performance? Nutrients 2017;9(9):946. https://pubmed.ncbi.nlm.nih.gov/28846654/
6. Expert Group on Vitamins and Minerals. Safe Upper Levels for Vitamins and Minerals. Food Standards Agency, 2003 (magnesium guidance level 400mg a day from supplements). https://cot.food.gov.uk/sites/default/files/vitmin2003.pdf

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