For some women the 5:2 diet may help protect against breast cancer

    17 June 2016

    Women who reduce their intake of calories for just two days a week lower their risk of breast cancer, according to a study published in the journal Breast Cancer Research.

    The researchers behind the study, a collaboration between the Genesis Prevention Centre in Manchester and Edinburgh University, performed breast biopsies on 20 women before and after they spent four weeks following the 5:2 diet.

    On average participants lost half a stone in weight, and 55 per cent of participants experienced a positive change in their breast cells.

    The 5:2 diet is a form of intermittent fasting, and involves eating about a quarter of the recommended calories for two days a week.

    Dr Michelle Harvie, the study’s lead author, said: ‘We know weight loss can reduce the risk of diseases such as breast cancer. However, people often find sticking to a continuous low-calorie diet difficult and can “fall off the wagon”, so to speak, very quickly.

    ‘While the study used a relatively small sample size, all participants were monitored very closely, with regular check-ups and consultations taking place so we knew they were definitely following the diet.

    ‘There are a number of reasons why some of the women didn’t experience changes in the breast; for example, they may have needed to spend a longer period of time on the diet or perhaps follow a different version of the two-day diet.’

    Instant analysis
    This was a prospective cohort study of obese women at high risk of developing breast cancer (defined as a risk exceeding one in six). Its aim was to assess any changes in breast gene expression as well as biochemical markers associated with the development of breast cancer.

    Intermittent energy restriction (two days of restricted calorie intake followed by five days of relaxed calorie intake of a Mediterranean diet and repeated four times a month), in the style of a 5:2 diet, was associated with mild degree of weight loss, total fat loss, and reduced insulin levels and insulin resistance, all of which reached statistical significance. Cellular changes in breast tissue were also seen, with half of patients exhibiting gene expression associated with increased catabolism (breakdown) and decreased anabolism (build-up) of cells in breast tissue.

    All these changes have been associated with a decreased risk of breast cancer in other studies.

    This interesting short-term study suggests potential in the management of patients at high risk of breast cancer. Intermittent fasting cannot yet be touted as a preventative measure given the short follow-up period. A study in which patient compliance is not an issue and long-term follow-up is performed would definitively answer the question of whether it could be.

    One of the major risk factors for breast cancer is obesity. This study indicates that even in the short-term there are alterations biochemically and body composition-wise associated with an improved method of eating, something that should increase compliance in those fed up of failing on traditional low-fat, calorie-restricted diets.
    Research score: 4/5