Losing weight can help reduce the risk of breast cancer by up to a third, a study has found.
Excess weight raises the risk of breast cancer as fat cells produce hormones that help drive tumours.
However, whether the risk could be reduced by a successful diet was not known till now.
Researchers tracked more than 61,000 women aged between 50 and 79 for 11 years.
"Relatively modest weight loss was associated with significant lowering of breast cancer incidence," said Rowan Chlebowski, lead researcher at from the Department of Medical Oncology and Therapeutics Research at City of Hope in the US.
"From this study, we have evidence that a weight loss strategy can be effective in lowering breast cancer risk in postmenopausal women," Chlebowski was quoted as saying by The Telegraph.
Researchers found that those who lost five per cent of their weight saw their breast cancer risk fall by 12 per cent.
The risk fell by 37 per cent for postmenopausal women who slimmed down by 15 per cent.