Could one of these pills help you slim?

‘natural’ weight-loss supplements essentially fall into four types: fat burners; appetite reducers; fat absorption blockers or blood sugar balancers. Here, we take a closer look at the science behind the claims.

FAT BURNERS

GREEN TEA: Caffeine and catechin (an antioxidant) in green tea have been shown in lab studies to speed up the rate at which our cells burn fat.

‘The problem arises when attempting to reproduce these benefits in supplement form,’ says Aidan Goggins, a pharmacist and independent adviser to the supplement industry.

A 2012 Cochrane review concluded the weight loss-promoting potential of green tea supplements was small and non-significant statistically.

Meanwhile, a 2020 review of 25 studies found slightly more pronounced weight- loss effects, but only at much higher doses (over 500mg a day). The longer-term use of high doses has now been linked to liver problems. RASPBERRY KETONE: This is the compound that gives raspberries their distinct aroma, and which advocates believe triggers the fat within cells to be broken down more effectively, helping the body burn fat faster.

But while some manufacturer-conducted studies claim to show that enormous doses (100 times the recommended amount) of raspberry ketone might increase metabolism, no clinical trials on humans have found weight loss benefits.

Raspberry ketone supplements ‘just don’t work, there’s no good science to support them’, says Mr Goggins.

APPETITE REDUCERS

GLUCOMANNAN: When ingested, this fibre from the root of the Asian konjac plant absorbs nearly 200 times its volume in water, forming a thick paste in the stomach.

This distends it, triggering the release of hormones linked to fullness and, because of this, it’s thought to act as an appetite suppressant.

However, a review by the University of Exeter in 2014 found no significant difference in weight loss between glucomannan and a placebo.

‘It certainly doesn’t have stellar result outcomes when studied,’ says Aidan Goggins, ‘so probably isn’t worth taking as a supplement.’

GUAR GUM: Another type of fibre (this time derived from the Indian cluster bean), this is thought to work by absorbing water and by physically plumping out in the gut to make you feel fuller. A small 2015 study by Nagoya Keizai University in Japan found that consuming 2g of guar gum per day reduced between-meal snacking by 20 per cent. ‘But far more studies are needed to prove it’s effective for weight loss,’ says Aidan Goggins.

FAT BLOCKERS

APPLE CIDER VINEGAR: Vinegar made from fermented apples has been hailed by some as useful for weight loss, due to its acetic acid content, said to slow the rate we absorb food. ‘Small human studies suggest apple cider vinegar can help with weight loss, but much more research is needed, and it certainly won’t “break down fat” as many claim,’ says Aidan Goggins.

‘Also, bear in mind that to get the therapeutic dose of 1.5g of acetic acid, you need 30ml of apple cider vinegar, so sufficient supplementation is only practical in liquid form, not in the many pills or gummies on the market.’ CALCIUM: Several studies have found that those who ate more dairy on average had lower levels of body fat. Some experts claim that this is thanks to the high amount of calcium in dairy, which somehow impairs the body’s ability to absorb fat from the food. ‘Although I’ve seen studies show people with high calcium diets tend to be slimmer, this effect hasn’t been replicated with taking calcium supplements,’ says Aidan Goggins.

BLOOD BALANCER

CHROMIUM: This mineral (found in wholegrains, broccoli and potatoes) plays a vital role in blood sugar regulation and helps the body to break down fat — leading to a belief that chromium supplements could help with weight loss.

However, chromium is only required in tiny amounts, with around 25mcg a day enough for adults, says the NHS.

‘Supplementation benefits have only been shown in people with chromium deficiency, which is extremely rare,’ says Aidan Goggins.

THE BOTTOM LINE: In 2021, a U.S. review of 315 trials of weight-loss supplements (in the journal Obesity) found that not only did they not result in dramatic weight loss — it was rare that people taking them lost any weight at all.