A brantastic way to tackle obesity

By Lauren Hoskin

It comes as no surprise that bulky fibre in the diet makes us feel full. Yet scientists have recently discovered a chemical, released by fibre-guzzling bacteria in the gut, that travels to the brain to suppress appetite. It is now thought that the chemical, called acetate is at least in part responsible for controlling our hunger.

Previous studies have investigated how fibre controls appetite, concluding that it works by a variety of mechanisms. Firstly, human enzymes cannot digest it, meaning that we can’t gain any substantial amount of calories from its intake. Secondly, chewing fibre often takes more time and effort than other foods. The extra chewing generates a greater amount of signals, transmitted to the brain to tell us that we’re full. Fibre also absorbs large quantities of water, so when our bellies feel full, we stop eating. Evidently, fibre is a wonder food for controlling weight gain.

Despite its merits, it appears that the amount of fibre we eat has decreased dramatically over the past 200 years with our changing dietary habits. Fibre can typically be found in fruit, vegetables, pulses and grains, yet these are often found in low quantities in junk food and ready meals. Along with an increased calorific intake and tendency to be couch-potatoes, all this contributes to the current obesity epidemic.

Road-side Pulse by Meena Kadri

Road-side Pulse by Meena Kadri

It is estimated that in Stone Age times, a typical diet would have included around 100g of fibre a day, whereas the modern day diet contains just around 15g. The discordancy between how our digestive systems have evolved and what we are now eating could be contributing to obesity. So how could things be different?

This new study identifies acetate as an appetite-suppressing molecule. Released in the gut, it travels through the body and accumulates in the area of the brain known for appetite suppression. This triggers a series of chemical reactions to stop us from wanting more food.

However, the chemical mechanism only works when fibre is consumed in huge quantities, meaning that people would have to make drastic changes to their diets to achieve the desired effects. Instead, the researchers behind this study suggest that acetate could be given as a drug in the future. This will require more work to determine how it could be given safely, but looks like a promising approach.