Nuts: a good source of fibre. Photo: William Meppem
We know that one size doesn’t fit all when it comes to diet or exercise. But, is there just one change we could all make if we want to lose weight?
A new study suggests there is.
And it is something we should eat more of, if we want to see results.
Simply increasing your fibre intake can have “clinically meaningful weight loss” on par with a restrictive diet telling you what to eat less of, the researchers found.
It can also improve blood pressure and insulin resistance.
To come to these conclusion, researchers from the University of Massachusetts Medical School recruited 240 adults with metabolic syndrome and randomly separated them into two groups.
One group was put on the arguably more complicated American Heart Association (AHA) diet which involves maximising fruit and vegetable intake while minimising sugar, salt and alcohol.
Guidelines include consuming 50 to 55 percent of calories from carbohydrates, 15 to 20 per cent of calories from protein, and 30 to 35 per cent of calories from fat; and limiting saturated fat to less than 7 per cent of energy, trans fat to less than 1 per cent of energy.
The second group was simply instructed to increase their fibre intake, via fruit, vegetables and wholegrains, to 30 grams per day.
Neither group was told to make any changes to their exercise regime.
Over the course of 12 months, they had their weight, blood pressure, blood sugar and inflammation levels measured.
No clear differences in these measures were recorded between the groups, leading the study’s author, Dr Yunsheng Ma to comment:
“By changing one thing, people in the fibre group were able to improve their diet and lose weight and improve their overall markers for metabolic syndrome.”
Associate Professor Amanda Salis from Sydney University’s Boden Institute of Obesity, Nutrition, Exercise & Eating Disorders says the study is encouraging in its simplicity.
“It’s important to note, however, that this does not mean that fibre is the new ‘magic bullet’ for weight loss,” she says.
“Rather, it’s likely that when people focus on increasing their fibre intake, they also make other improvements to their diet, as a passive ‘side effect’.”
She notes, for example, that actively trying to increase your fibre intake means increasing your fruit and vegetable intake, which means you are less likely to have room for the kilojoule-heavy, nutrient-light fast foods and snacks.
Charlene Grosse, accredited practising dietitian and spokeswoman for the Dietitians Association of Australia (DAA), agrees.
“By increasing your high-fibre foods you are automatically leaving less room for higher calorie, lower nutrient foods,” she says.
“It’s a good message – to focus on what we can do better… In the latest survey, only about 7 per cent of Australians had the [recommended] five serves of vegetables a day.”
To reach the 30 grams of fibre a day requires some dedication.
Half a cup of cooked vegetables, for instance, contains around three grams, two slices of wholegrain bread contains a similar amount, while half a cup of legumes has about six grams.
As good as a simple message is, we still need to consider the broader picture of our diet and making a range of improvements, Grosse says.
“The other thing to note is that the study was relatively small (240 adults), and this is not enough people to be able to say with certainty that focusing on just one dietary change is as good as focusing on multiple dietary changes,” adds Salis.
This is something the study’s authors acknowledge.
“A simplified approach to weight reduction emphasising only increased fibre intake may be a reasonable alternative for persons with difficulty adhering to more complicated diet regimens,” they conclude.
Adds Salis:
“This is, however, an exciting area for further research, because anything that can make health messages more ‘do-able’ will help more people.”
FIBRE
The DAA recommend eating 25 to 30 grams of fibre a day. But, Grosse that not everyone copes with this amount. This much fibre can exacerbate symptoms in those with irritable bowel syndrome, she says.
For others, who eat very little fibre, Grosse suggests slowly increasing your intake to allow your digestive system to adjust.
Fibre helps to keep your digestive system healthy and reduce the risk of constipation, diverticular disease, haemorrhoids and bowel cancer.
There are two different types of fibre:
Insoluble fibre adds bulk and helps to keep the bowels regular. Foods high in insoluble fibre include whole grain breads and cereals, the skins of fruit and vegetables, nuts and seeds, raw lentil, kidney beans and chickpeas.
Soluble fibre slows down digestion, soluble fibre helps people feel full for longer after eating. It can also help stabilise blood glucose levels in people with diabetes and may help to lower LDL (bad) cholesterol levels.
Soluble fibre is found in fruits and vegetables, dried beans, lentils and oats.
Associate Professor Amanda Salis is seeking participants from the Sydney metropolitan area for clinical weight loss trials. For more information, contact her team on tempo.diet@sydney.edu.au