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.
Breast Cancer Risk
Behavioral: Combined exercise- + diet-induced weight loss
|Study Design:||Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Open Label
Primary Purpose: Basic Science
|Official Title:||The Effects of Equivalent Weight Loss With or Without Exercise Training on Breast Cancer Risk Biomarkers in Postmenopausal Women: the SHAPE-2 Study|
- serum sex hormone levels [ Time Frame: 21 weeks ] [ Designated as safety issue: No ]Estradiol (total, free), estrone, testosterone, sex hormone binding globulin.
- anthropometrics and physical fitness. [ Time Frame: 21 weeks ] [ Designated as safety issue: No ]BMI, weight, waist- and hip-circumference, total body fat (DEXA scan), abdominal fat (subcutaneous and visceral, MRI-abdomen) and physical fitness (maximal exercise capacity test by the ramp protocol).
|Study Start Date:||February 2012|
|Estimated Study Completion Date:||June 2013|
|Estimated Primary Completion Date:||June 2013 (Final data collection date for primary outcome measure)|
Experimental: Diet-induced weight loss
The diet-induced weight loss group will follow a calorie restricted diet. They are asked to keep their habitual sedentary lifestyle. The aim of this group is to loose 5-6 kg of body weight in 14 weeks time.
Energy restricted diet, according the national guidelines for healthy nutrition, creating a mean energy deficit of 500 kCal/day.
Experimental: Combined exercise- + diet-induced weight loss
Participants in the exercise- plus diet-induced weight loss group are enrolled in an exercise programme. Next to the exercise programme, they will follow a calorie restricted diet.
The aim of this group is to loose 5-6 kg of body weight in 14 weeks time.
Behavioral: Combined exercise- + diet-induced weight loss
Exercise programme of 2 hours per week fitness containing endurance and resistance training. And 2 hours of Nordic Walking. Equivalent to an energy expenditure of 350 kCal/day.
Next to the exercise programme participants will follow an energy restricted diet according to the national guidelines of healthy nutrition creating an extra energy deficit of 250 kCal/day.
No Intervention: Control, stable weight
The control group is asked to follow a baseline isocaloric diet and to not change their habitual sedentary lifestyle.
Postmenopausal women who are sedentary or overweight, have an increased breast cancer risk. It is suggested that these two factors mediate breast cancer risk mainly through sex hormone-related pathways. However, an inactive lifestyle and obesity are highly correlated and it is not clear which is most relevant to risk.
Literature shows that weight loss/ fat loss reduces postmenopausal sex hormone levels, but the question is if there is an additional beneficial effect on hormones of reaching this weight loss by physical activity instead of nutritional interventions.
In this three-armed, two-center intervention study, 250 sedentary postmenopausal women who are aged 50-69 years will first enter a run-in period of 5 weeks. During this period, all participants get a diet, adapted to the guidelines for healthy nutrition, meeting their energy expenditures to maintain stable weight. After this run-in phase they are randomly allocated to a (1) diet induced weight loss group, (2) a combined exercise and diet induced weight loss group or (3) a control group. Participants allocated to the dietgroup will get a calorie restricted diet of -500 kCal/day, they will remain their habitual exercise pattern. Participants in the combined group will follow an exercise programme (combined endurance and strength) of 4 hours of sports per week with an average energy expenditure of 350 kCal/day and a, less strict. And a calorie restricted diet of -250 kCal/day. The aim of both intervention groups is to loose 5-6 kg of body weight during the 14 week intervention period. Participants in the control group are requested to retain the baseline diet and their habitual exercise pattern. Primary study parameters measured at baseline and after 21 weeks are: serum concentrations of endogenous estrogens, endogenous androgens and sex hormone binding globulin. Other study parameters include: body fat distribution, amount of total and abdominal fat, weight, BMI, physical fitness, blood pressure and lifestyle factors.
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. Furthermore, we are specifically interested whether weight loss mainly due to physical exercise induces greater amounts of fat loss (total and abdominal) and subsequently results in more favourable effects on these hormones compared to equivalent diet-induced weight loss.