Bad news for women who follow the keto diet – all that fat could be doing you more harm than good.

A long term analysis based on data from the Women’s Health Initiative in the US reveals that lowering your fat intake and upping your fruit and veg consumption lowers your chance of dying from breast cancer.

Researchers from the Los Angeles Biomedical Research Institute at the Harbor-UCLA Medical Center tracked the diets of nearly 50,000 women over 20 years. Half the participants followed their usual diet while the other half slashed their fat intake by 20% and added an extra portion of fruit, veg and grains to their diet.

Results showed the second group had a 20% lower chance of dying from breast cancer.

The findings will be presented at the American Society of Clinical Oncology in Chicago.

The diet component of the study looked at 48,835 women aged 50-79 who didn’t have breast cancer.

While its findings are promising, the study’s main goal was to see if a healthier diet lowered the risk of developing breast cancer. Unfortunately, it did not.

Breast cancer affects one in eight Australian women.

A positive outcome of the study is that it revealed a way to improve the odds of survival for those diagnosed.

“This is the first randomized trial where breast cancer was an endpoint, and we’ve been able to show a reduction in deaths,” Dr Chlebowski, who led the study, told NBC News.