Diet & Fitness 

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Do diet pills work?

It’s a dream come true: a pill that helps you lose weight. But should you buy in?

Conjugated linoleic acid

Anna, aged 40, has been trying to lose weight for the past year, but hasn’t been able to shift the final 12 pounds needed to achieve her goal. A friend recommended that she try a diet supplement containing conjugated linoleic acid (CLA). She has now been taking four 500mg capsules a day for the past month and has lost several pounds.

So, what does CLA claim to do? CLA is a fatty acid that is produced by bacteria in the gut of animals such as sheep, cows and turkeys. It is also found in small amounts in plants such as sunflowers and safflowers. It is thought that humans can also make CLA, given the right balance of bacteria in their gut and a healthy diet. Its function is to help transport, store and metabolise fats in the body.

Most of the research into CLA has involved studying its anti-cancer properties in animals and human volunteers. More recently, studies have looked into CLA’s ability to increase lean tissue (build muscle), while reducing fatty tissue in the body.

So far, scientific research on CLA's weight loss claims have been mainly based on animal studies, although these have shown an improvement in the muscle-to-fat ratio i.e. fat loss and muscle gain, very few studies have been conducted using human volunteers, whilst some have shown a loss in fat, others have shown either negligible effects or even in increase in fat mass. We are still awaiting data from long-term studies involving humans before we can draw conclusions as to its efficiency and safety in helping people lose weight. In the meantime, I would suggest caution in taking CLA supplements and for pregnant and breastfeeding mums to avoid this altogether.

Fat magnets
Pat, aged 28, has been yo-yo dieting since she was a teenager. She has tried numerous diet and herbal pills to help her lose weight, the latest being fat magnets. Pat has lost a couple of pounds in the last week.

So, how do fat magnets work? The principal ingredient of fat magnets is chitosan – that’s crushed-up shellfish shells to you and me. It is claimed that chitosan has a positive ionic charge, which attracts negatively charged fat like a magnet, reducing the absorption of fat from the gut and thus reducing the absorption of cholesterol.

Again much of the scientific evidence for chitosan has been drawn from experiments using rats. A handful of studies have been published involving human volunteers, no significant weight differences were shown among subjects taking chitosan and those taking a dummy pill. Another study found that the amount of fat removed by chitosan was insignificant and therefore have no effect in contributing to weight loss. One potential problem with chitosan is that it may block the absorption of fat-soluble vitamins such as vitamins A, D and K, which means long-term use may lead to a deficiency. My advice is: don't bother to waste your money on these.

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