These findings have been used to develop diet aids. In particular, dietary fibre isolated from
various plants has been used to decrease appetite. Very few scientific studies have been carried
out on this idea, and those rat have been done have found a slightly positive effect or no effect.
There is another point to remember: some components of dietary fibre are extensively broken
down by large intestine bacteria. This process can reduce short-chain fatty acids which are used as
fuel energy) by the body. Such dietary fibre has an energy value of about 13 kilojoules per gram
(3 kilocalories per gram) compared with digestible carbohydrate like sugar or starch (which can
be digested and therefore absorbed in the small intestine) at 17 kilojoules per gram (4 kilocalories
per gram). Of course, the amounts of dietary fibre used in this way may be relatively small, say 5
,10 grams, amounting to 60 to 120 kilojoules, but it is not zero.
There is a risk that some dietary fibre supplements taken in tablet form may take up water and swell after swallowing, blocking off the upper gut (oesophagus). Such forms of dietary fibre have now been banned in Australia.