Impact of weight loss on insulin resistance in breast cancer survivors

This study aimed to evaluate the effects of a behavior-based weight loss program on insulin resistance for breast cancer survivors. This study found that breast cancer survivors who achieved 5% or more weight loss saw a significant reduction of insulin resistance.

Breast cancer survivors with excess weight are more likely to have negative breast cancer outcomes.  Insulin resistance is often related to excess weight. Insulin is a hormone needed to break down the sugar taken in from food. In those who are insulin resistant, more and more insulin is needed. Insulin resistance is associated with type 2 diabetes. 

Insulin resistance is also associated with an increase in certain blood markers associated with an increased risk of breast cancer. It is not clear whether a behavior-based weight loss program could reduce insulin resistance, or whether it would have an effect on blood marker levels.

This study included 51 early stage breast cancer patients, who had completed treatment and were also overweight, Patients took part in a six-month behavior based weight loss program. This program consisted of calorie reduction, exercise and behavior change. Biomarkers related to insulin resistance were obtained before and after the weight loss program. Results from participants who achieved 5% or more weight loss were compared to those who lost less weight.

69% of all participants were considered to have pre-diabetes or diabetes at the start of the program. Participants who achieved a 5% or more weight loss had significantly lower fasting insulin and other blood markers related to insulin. 

This study found that breast cancer survivors who achieved at least a 5% weight loss demonstrated significant reduction of insulin resistance.

A diagnosis of diabetes was an excluding factor for this trial. However, a high proportion met criteria for pre-diabetes or diabetes at baseline. Pre-diabetes appears to be under recognized in overweight breast cancer survivors.