The Effects of Equivalent Weight Loss With or Without Exercise Training on Breast Cancer Risk (SHAPE-2)

Physical inactivity and overweight are two accepted risk factors for breast cancer. However, because of their correlation it is not clear which is most relevant to risk. The investigators now set out to study whether physical activity in addition to weight loss by diet only, affects sex hormone levels, known to be related to breast cancer risk. In the SHAPE-2 study 250 healthy overweight/obese and physically inactive women are randomly allocated to a diet-induced weight loss group, a combined exercise- and diet-induced weight loss group or a control group. The aim of the first two intervention groups is to loose 5-6 kg of bodyweight, either by dieting or mainly by increased physical activity. Measurements are performed at baseline and after 21 weeks, the end of the study period. The aim of this study is to provide insight into the effect of weight loss mainly driven by exercise compared to equivalent weight loss due to nutritional calorie restriction on breast cancer biomarkers.