London [UK], Feb. 9 : Researchers have found swapping white rice for its brown alternative speeds up weight loss and is the equivalent of a 30-minute brisk walk.
Making the small daily change to include more fibre can help to cut 100 calories each day, a study found.
This difference is about the same amount that would be burnt off by a brisk half-an-hour walk, experts discovered.
Researchers at Tufts University in Massachusetts took two groups of people and fed them diets similar in total energy, total fat, and the number of fruit, vegetable and protein servings.
The only difference was in the source of grain. One group ate wholegrains such as brown rice and whole wheat, while the other consumed white rice and refined white flour.
They found that the diet with more wholegrains led to people developing a faster metabolism, burning more calories.
They also absorbed fewer calories in their digestive systems. As well as these benefits there was a 'modest' improvement in their immune systems, with the people on wholegrains producing more T-cells, which deal with infections.
Numbers of beneficial gut bacteria were also found to increase. The study was conducted over eight weeks with 81 men and women aged between 40 and 65. For the first fortnight, participants ate the same food. Then the participants were split in two groups, with one eating the high fibre diet, and the others eating low fibre.
Researchers measured the weight, metabolic rate, blood glucose, calories excreted, hunger and fullness.
They found that hunger, fullness and diet satisfaction were no different between the different diets. Eating a higher fibre diet with whole grains - matching US dietary recommendations of 3oz (85g) of wholegrains for women and 4oz (113g) of wholegrains for men per day - led to the loss of an extra 100 calories a day, or 700 calories over a week.
This was caused by a higher resting metabolic rate and also lower absorption of calories in the digestive system, researchers said.
Dr Phil Karl, who led the study, said: 'Many previous studies have suggested benefits of whole grains and dietary fibre on chronic disease risk.
'This study helps to quantify how whole grains and fibre work to benefit weight management, and lend credibility to previous reported associations between increased whole grains and fibre consumption, lower body weight and better health.' Dr Susan Roberts co-author said: 'We provided all food to ensure that the composition of the diets differed only in grain source.
'The extra calories lost by those who ate whole grains was equivalent of a brisk 30 minutes walk - or enjoying an extra small cookie every day in terms of its impact.' In the UK, the recommended amount of fibre to take in is 30 grams a day for an adult, although most people eat much less - an average of around 12 grams.