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The question

What's your opinion of fibre capsules used to aid weight loss? Are they safe? Can they help?

The answer

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Some may help – provided you're following a calorie-reduced diet. But there's no evidence that fibre supplements promote weight loss on their own.

The particular supplement that has been studied is called PGX. It is a blend of plant fibres that, once consumed, absorb water in the body. As a result, the supplement is supposed to help control your appetite so you will eat fewer calories.

There is some preliminary evidence to support this. In one study of 31 healthy weight teenagers, taking PGX 90 minutes before a pizza meal – compared to two other fibre supplements – resulted in reduced food and calorie intake. However appetite scores and food intake over the next 24 hours did not differ between the three groups.

In another small study, 29 overweight men and women who exercised, followed a 1,200 calorie diet and took PGX before meals lost on average 1-2 lbs per week during the 14 week study. However, keep in mind there was no comparison group who did not take PGX during their weight loss program. It's impossible to say to what extent, if any, PGX helped these individuals stick to their diet.

Bottom line: there really isn't any evidence that taking PGX or any other fibre supplement will help you lose more weight than diet and exercise alone. It is possible that PGX can help reduce your appetite, making it easier to follow a low calorie diet.

If you want to try PGX, it is safe for most healthy adults. The product website warns that the following people should not use it: people with kidney disease or congestive heart failure; anyone who is taking a large number of medications that must be taken with food and/or without food; anyone who has difficulty swallowing or pre-existing bowel abnormalities such as GI strictures or impaired mobility. Such people should consult their health care practitioner before use.

But in my opinion, the tried and true method for losing weight is diet and exercise – following a realistic plan that can be sustained over the long term.

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When it comes to weight loss, I'm afraid there are no magic bullets or quick fixes.

Send dietitian Leslie Beck your questions at She will answer select questions, which could appear in The Globe and Mail and/or on The Globe and Mail web site. Your name will not be published if your question is chosen.

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The content provided in The Globe and Mail's Ask a Health Expert centre is for information purposes only and is neither intended to be relied upon nor to be a substitute for professional medical advice, diagnosis or treatment.

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