Women who go on a low carb diet just two days per week have a lower risk of developing breast cancer compared to those who follow a standard calorie-restricted diet every day of the week, in order to lose weight and lower their insulin blood levels. Long-term high blood insulin levels are known to raise cancer risk. These findings were presented by scientists from Genesis Prevention Center at University Hospital in South Manchester, England, at the 2011 CTRC-AACR San Antonio Breast Cancer Symposium.

The researchers stressed that a larger, longer-term additional study is required.

Michelle Harvie, Ph.D., SRD, a research dietician at the Genesis Prevention Center, who presented the study said:

“Weight loss and reduced insulin levels are required for breast cancer prevention, but [these levels] are difficult to achieve and maintain with conventional dietary approaches.”

Harvie and her team set out to compare three different 4-month-long diets to assess the effects on weight loss and blood markers of breast cancer risk in 115 women who had a family history of breast cancer. The researchers randomly assigned patients into three groups:

  • The low cal/carb group – they followed a calorie-restricted, low-carbohydrate diet
  • The part-time low-carb group – they followed an “ad lib” low-carbohydrate diet whereby patients were allowed to consume unlimited proteins and healthy fats, like lean meats, olives and nuts for 2 days per week
  • The Mediterranean diet group – a standard, calorie-restricted daily Mediterranean diet for seven days per week

Both low-carb diets were found to be more effective than the Mediterranean diet in achieving weight loss, reducing body fat, and lowering insulin resistance.

  • Weight loss – in the two low-carb groups the participants lost an average of 4kg (approx. 9 pounds) compared to 2.4kg (approx 5 pounds) in the Mediterranean diet group.
  • Insulin resistance – this went down 22% in the low cal/carb group, 14% in the part-time low-carb group, and 4% in the Mediterranean diet group.

Harvie said:

“It is interesting that the diet that only restricts carbohydrates but allows protein and fats is as effective as the calorie-restricted, low-carbohydrate diet.”

Harvie and her team are planning on studying carbohydrate intake and breast cancer.

Written by Petra Rattue