People shopping for weight loss supplements usually look at "fat burners", L-carnitine and diet protein. We explain what's in them and what the evidence does and doesn't show. NHS advice on losing weight focuses on diet and activity, not supplements.
Weight management · Fat burners · L-carnitine · Diet & lean protein · Protein bars
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What does the NHS advise for losing weight?
The NHS suggests aiming to lose 0.5 to 1kg (1 to 2lbs) a week, getting active for 150 minutes a week, eating your 5 A Day, swapping sugary drinks for water and not skipping meals. It warns against losing weight suddenly with crash diets.
The NHS also says to only take weight loss medicine if it has been prescribed for you. Food supplements are not weight loss medicines.
Do weight loss supplements work?
The products in this collection don't carry an authorised weight loss claim. The GB register of authorised health claims allows "Glucomannan in the context of an energy restricted diet contributes to weight loss" only for foods with 1g of glucomannan per portion. The label must also say the effect needs 3g a day, in three doses with water before meals. There is a similar claim for meal replacements that meet strict nutritional rules.
Products sold as "fat burners" or "thermogenics" usually contain plant extracts and often caffeine, and L-carnitine products contain a compound made from amino acids. Check the label, and know that we make no weight loss claims for them.
"My biggest takeaway from sourcing these products is that customers need more transparency, not more marketing claims," says Andy Arshad, who runs SupplementHQ.
Is protein useful when losing weight?
Protein has no weight loss claim, but one authorised claim is relevant: "Protein contributes to the maintenance of muscle mass", where a product is at least a source of protein. Diet protein powders and bars still contain calories, so count them in your daily total. Browse diet and lean protein.
Are fat burners safe?
Check the caffeine per serving first. EFSA (the European Food Safety Authority) says single doses of caffeine up to 200mg, and up to 400mg a day, raise no safety concerns for healthy adults, and up to 200mg a day in pregnancy. Count every source, including coffee, tea and energy drinks.
Speak to your GP or pharmacist before using any stimulant product if you have a heart condition or high blood pressure, are pregnant or breastfeeding, or take medication. These products are for adults only.
We sell the products on this page. That's our commercial interest, and it's why we show the evidence alongside them. This page is general information for adults, not personalised medical advice. Food supplements should not replace a varied, balanced diet.
Written by Andy Arshad, SupplementHQ. Last reviewed 11 October 2026.