Compare weight management products on what's in them and what each serving costs: caffeine per serving in fat burners and thermogenics, carnitine per serving, and calories and protein in meal shakes and diet foods. No supplement replaces a calorie-controlled diet and regular activity, and we don't claim any product here causes weight loss.
Fat burners · Thermogenics · L-carnitine · Diet & lean protein · Meal replacements · Protein powder
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How does the NHS say to lose weight?
The NHS advises you to aim to lose 1 to 2lbs, or 0.5 to 1kg, a week, to avoid losing weight suddenly with diets, and to get active for 150 minutes a week. It recommends cutting down on food high in sugar and fat, not skipping meals, and offers the free NHS Weight Loss Plan app.
None of that advice involves supplements. We list the NHS approach first because it's the evidence-based starting point, and the products on this page are at most an add-on to it.
Do weight loss supplements work?
Mostly not, or not by much. The US National Institutes of Health says there's little scientific evidence that weight-loss supplements work, and that many are expensive and some can interact with medicines.
"My biggest takeaway from sourcing these products is that customers need more transparency, not more marketing claims," says Andy Arshad, who runs SupplementHQ. That's why we describe what's in each type of product rather than what it promises.
What's in this collection?
Weight management is a broad category, and the products in it work in very different ways. Based on the product names we stock, they fall into four groups.
| Type | What it usually contains | What the NIH says about the evidence |
|---|---|---|
| Fat burners and thermogenics | Caffeine, often with green tea extract, chromium or other ingredients | Caffeine "might help you lose a little weight"; tolerance can reduce the effect |
| L-carnitine | L-carnitine or acetyl-L-carnitine, as capsules, liquids or shots | "Might help you lose a small amount of weight" |
| Meal shakes and diet protein | Protein, carbohydrate, vitamins and minerals in a measured portion | Not a supplement effect: they replace or add a known number of calories |
| Other formulas | Ingredients such as CLA, chitosan or chromium | CLA and chromium: a very small amount at most; chitosan binds too little fat to help much |
Which weight loss products have authorised claims?
Very few. In Great Britain, glucomannan (konjac fibre) is the only food supplement ingredient with an authorised weight-loss claim: "Glucomannan in the context of an energy restricted diet contributes to weight loss", which applies only at 3g a day, taken in three 1g doses with 1 to 2 glasses of water before meals, as part of an energy-restricted diet.
Meal replacements also have authorised claims, but only when a product meets strict rules on calories, protein, fat, vitamins and minerals per meal and is used to replace one or two main meals in an energy-restricted diet. Not every shake qualifies, so check the label for the claim and its conditions. Caffeine, L-carnitine and green tea have no authorised claims.
Are fat burners and diet pills safe?
Food supplements sold legally in the UK must meet food law, but caffeine-heavy products can still cause side effects. EFSA says up to 400mg of caffeine a day from all sources is safe for healthy adults, and up to 200mg a day in pregnancy, so add the caffeine in any product to your coffee, tea and energy drinks.
Be wary of slimming products sold online. The MHRA, the UK medicines regulator, warns that illegally sold weight-loss products may be fake, contaminated or incorrectly dosed, and says not to buy prescription-only weight-loss medicines without a prescription. If you're thinking about weight-loss medicines, it advises speaking to your GP or pharmacist. We sell food supplements and foods only, not medicines.
Where does protein fit when you're dieting?
Protein can make it easier to meet your daily protein needs on fewer calories, but it doesn't cause weight loss on its own. Where a food is at least a source of protein, it may say that "protein contributes to the maintenance of muscle mass".
Browse diet and lean protein or the full protein powder range, and compare calories and protein per serving rather than the word "diet" on the tub.
How do you compare weight management products?
Compare what you get per serving and what each serving costs. For caffeine products, check caffeine per full serving; for carnitine, the amount per serving; for shakes, calories and protein per serving.
"Two products that look almost identical on the shelf can offer different value," says Andy.
How to compare value (example figures, not real products): a £25 bag of meal shake with 20 servings costs £1.25 a serving. A £40 bag with 40 servings costs £1 a serving. If both give 200kcal and 20g of protein per serving, the larger bag is 20% cheaper for the same nutrition.
Who should avoid weight loss supplements?
Speak to your GP or pharmacist before taking any weight loss supplement if you're pregnant or breastfeeding, have a medical condition such as heart, liver or kidney disease, have diabetes, or take medication. Supplements for under-18s should be discussed with a GP or pharmacist first.
The NIH also warns that some weight-loss products sold online have been found to contain hidden prescription drugs or controlled substances not listed on the label. If you're unsure what you need, read our guide to what supplements you actually need.
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.