Do natural weight loss supplements work?
Not by enough to matter. A review of 54 trials found no herbal pill with good proof of the 2.5 kg loss that counts. And some pills sold as herbal have hidden a withdrawn medicine.
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Do natural weight loss supplements work?
Not by enough to matter. A 2020 review pooled 54 trials of herbal pills in adults with overweight or obesity. Each pill was tested against a dummy pill.
The team counted 2.5 kg or more as a loss that matters. Their verdict: there’s not enough evidence to recommend any of the herbal pills they studied.
Sources: Maunder 2020; Cochrane: chitosan; Cochrane: chromium; Onakpoya 2014
A bigger 2021 review checked 315 trials of supplements and other remedies. Only 52 were low risk of bias. Just 16 of those found a clear difference in weight, and the review called the good evidence limited.
Your move: before you buy, find your supplement in the next section and see what it did in trials.
Which supplements are good for weight loss?
| Supplement | What trials found | The catch |
|---|---|---|
| Green tea extract | 0.04 kg more lost in 6 trials outside Japan. | Pills giving 800 mg a day of EGCG may be linked to liver strain. |
| Glucomannan (konjac fibre) | 0.22 kg, no clear difference. | Tummy discomfort, diarrhoea or constipation. |
| Chromium | 1.1 kg after 12 to 16 weeks. | Low-quality evidence. |
| Chitosan | 1.7 kg across all trials. | The better trials found a minimal effect. |
| Garcinia cambogia | No effect seen. | In the 2020 review of herbal pills. |
| White kidney bean extract | Beat a dummy pill. | But by too little to matter. |
Sources: Cochrane: green tea; EFSA; Onakpoya 2014; Cochrane: chromium; Cochrane: chitosan; Maunder 2020
So what’s the best natural weight loss supplement? None of the reviews names one.
Green tea’s 0.04 kg is about the weight of a slice of bread. The Cochrane team said it was not likely to be clinically important.
Most herbal trials ran for 12 weeks or less. The review says long-term safety still needs testing.
Seen berberine or vinegar sold for weight? Both have their own guides: berberine and apple cider vinegar. For teas, see weight loss drinks.
Are weight loss supplements safe?
Not always. The UK medicines regulator (MHRA) puts it plainly: “natural” does not mean “safe”.
In 2015 it seized more than 240,000 doses of slimming pills. Some were sold as all herbal or natural but held a hidden medicine.
That hidden medicine was sibutramine. It was withdrawn in 2010 because it raised the risk of heart attacks and strokes.
Illegal products may be fake or wrongly dosed, or hold drugs not on the pack. The MHRA says they can cause heart problems, effects on the mind and dangerously low blood sugar.
Green tea extract needs care too. As a supplement, 800 mg a day of its main catechin (EGCG) may be linked to liver strain. Experts couldn’t name a safe dose.
Checks before you buy a slimming pill
- Look for the THR logo and a THR or PL number on herbal products.
- Buy medicines only from registered UK pharmacies or legitimate shops.
- Skip products on social media that promise quick fixes or have unusually low prices.
- Choose brewed green tea over green tea extract pills.
- Talk to a doctor or pharmacist before you buy slimming pills online.
- Report suspicious websites or products to the MHRA Yellow Card scheme.
More on herbs and the liver: herbal supplements and liver damage.
What works better than supplements?
The NHS says losing 5 to 10% of your body weight can improve your health. For someone who weighs 90 kg, that’s 4.5 to 9 kg.
That’s more than the 2.5 kg no herbal pill had good proof of. Here’s the NHS route to it.
What the NHS offers instead of pills from a shop
- 1
Steady changes
Eat fewer calories, move more and aim to lose 0.5 to 1 kg a week.
- 2
A weight programme
Coaching, group support or online classes. You can self-refer to some.
- 3
Medicines
Depending on your BMI and other health conditions, usually alongside diet and activity.
Source: NHS
Orlistat is a licensed medicine, not a supplement. It stops your body absorbing some fat. You can buy a lower dose from a pharmacy.
Never stop or change a prescribed medicine without your prescriber. To plan your first step, see calories to lose weight, how much weight you can lose in a month and weight loss programmes.
When to speak to a GP
Speak to a GP if:
- You keep losing weight without changing your diet or exercise.
- You feel very tired, pee more than usual (especially at night), feel thirsty all the time, or have blurred vision or cuts that heal slowly. These can be signs of type 2 diabetes.
- You worry a lot about your weight, eat very little, or make yourself sick or take laxatives after you eat. These can be symptoms of an eating disorder.
- Your BMI (weight-for-height score) is overweight or obese and you want help to lose weight.
Taken more orlistat than you were prescribed? Get help from NHS 111.