It found that while women who ate a large amount of refined grain foods were more likely to be obese, those with the greatest whole grain consumption weighed less and are less likely to gain weight.
The study, published in November's American Journal of Clinical Nutrition (vol 78, no 5, pp 920-927), investigated the relation between intake of dietary fibre and whole- or refined-grain products with weight gain over time.
They used a prospective cohort study on more than 74,000 US female nurses, aged 38-63 years in 1984 and free of known cardiovascular disease, cancer, and diabetes at baseline. Their dietary habits were assessed in 1984, 1986, 1990, and 1994 with validated food-frequency questionnaires.
Average weight, body mass index, long-term weight changes, and the odds ratio of developing obesity (BMI of 30) according to change in dietary intake were recorded.
The researchers from the Brigham and Women's Hospital and Harvard Medical School found that women who consumed more whole grains consistently weighed less than women who consumed less whole grains.
Over 12 years, those with the greatest increase in intake of dietary fibre gained an average of 1.52 kg less than did those with the smallest increase in intake of dietary fibre independent of body weight at baseline and age.
Women in the highest quintile of dietary fibre intake had a 49 per cent lower risk of major weight gain than did women in the lowest quintile.
The team concludes that "weight gain was inversely associated with the intake of high-fibre, whole-grain foods but positively related to the intake of refined-grain foods, which indicated the importance of distinguishing whole-grain products from refined-grain products to aid in weight control".