Award winning Prevent Breast Cancer research dietitian, Dr Michelle Harvie has attracted press coverage from around the world with her ground-breaking intermittent diets for women with breast cancer and women at high risk of breast cancer. Information about our intermittent diet “and our research has been published in in the book “The 2-Day Diet”. Preliminary findings from our research suggests that women could achieve and maintain weight loss and reductions in hormones levels linked to cancer risk by simply changing to this healthier diet and lifestyle plan.
We were one of the first groups to report that weight loss can reduce the risk of breast cancer. A collaborative study with the Iowa Women’s Health Study Cohort (34,000 women) in 2005 found women with modest weight loss (5% i.e. 10 pounds of weight) reduced their risk of developing breast cancer by 25-40%. We have been developing and testing innovative intermittent diets for weight loss and breast cancer prevention since 2006. Intermittent diets involve 2 days of restricted calories per week and 5 days of normal healthy eating. The initial trial compared a very simple milk and vegetable intermittent low calorie diet (650 kcal / day) for 2 days / week to a daily low calorie diet (~ 1500 kcal / day for 7 days). Weight loss was similar between the 2 diets but the key finding of this study was that intermittent diet led to greater reductions in the cancer promoting hormone insulin. On non diet days (five days after the intermittent diet) there was a 25% greater reduction in insulin with a further 25% reduction during the 2 diet days.
Our follow up study funded by Prevent Breast Cancer in 2009 – 2012 tested a new version of the intermittent diet. This 2 day diet involved 2 low carbohydrate, high protein, low calorie days which allowed a greater choice of food and protein and ensured our dieters were not hungry on their diet days. This new improved 2-Day Diet, was more effective and easier to follow than a standard daily diet and had a better compliance and success rate. Sixty – five percent of the 2 day dieters were successful and lost at least 5% of their weight compared to 40% of the daily dieters. The 2 day dieters lost on average 6 kg of fat compared to 4.9 kg in the daily dieters. The 2 day dieters adhered to the 2 day diet and also had a carryover effect which meant they reduced their calorie intake on their non diet days. The 2 day dieters had greater reductions in insulin both on non diet and diet days.
Ongoing Prevent Breast Cancer funded studies are examining the changes that occur in the breast and key fat stores in the body when women follow either an intermittent or daily diet . These detailed follow up studies will tell us whether the 2 day diet or daily restricted diets have different are likely to lead to real reductions in weight , risk of breast cancer and risk of other weight related diseases. i.e. other cancer, heart disease, stroke, diabetes and dementia.
Breast Risk Reduction Intermittent Diet Evaluation-1 study BRRIDE – 1
Low calorie diets are a potential strategy for breast cancer prevention. We have shown that a strict daily low calorie diet for 4 weeks (800 kcal 60% reduction in calorie intake) has beneficial effects on healthy breast cells within a healthy woman’s breast. Our previous study found big changes in the pattern of expression of genes (the instructions in all of the cells in our bodies) of healthy breast calls which were likely to make the cells more resistant to developing breast cancer.
This level of daily calorie restriction is not feasible in the general population. Our 2 day diet includes severe calorie restriction (60%) for just 2 day / week and is proven for weight loss and to improve blood markers of breast cancer risk. The BRRIDE-1 aims to assess whether our 2 day diet also has beneficial effects on gene expression in the breast cells which are likely to make the cells more resistant to developing breast cancer. Some genes may become active and switched on and some inactive and switched off.
What happens on the project?
Twenty five high risk women aged 35 – 45 will be asked to follow a 2 day diet for one month. We will examine the effects on gene expression within healthy breast cells before and after the 2 day diet to see if any genes become more active and switched or become inactive and switched off. We will also assess any changes brought about with the 2 day diet on genes expression in circulating white blood cells and levels of metabolites in the blood and urine to see whether changes in the blood compare to those we see in the breast cells.
What impact will this project have?
Beneficial effects of the 2 day diet within breast cells and / or any of the blood markers will indicate whether the diet is likely to help reduce risk of breast cancer.
Breast Risk Reduction Intermittent Diet Evaluation-2 study BRRIDE – 2
Overweight women often have large fat cells in their breast which increase the amount of oestrogen and inflammation within the breast. Overweight women can also store fat in the liver and the abdomen where it increases inflammation and increases circulating levels of insulin, sex hormones, fat produced hormones and inflammation. These changes in the breast and liver are all important in the development of breast cancer
Low calorie diets reduce the fat stores in the liver and abdomen and reduce insulin levels hence reduce cancer risk. Intermittent dieting is an increasingly popular method of dieting (2 day diet book, Harvie & Howell,) which leads to a great reduction in insulin resistance than daily dieting with comparable weight loss.
This study is testing whether an intermittent low calorie diet will lead to a greater reduction in liver fat compared to a calorie matched daily low calorie diet. This study will define the metabolic effects of intermittent compared to standard daily dieting and inform the value of intermittent vs daily diets as a potential cancer risk reduction strategy.
What happens on the project?
Twenty six women obese pre-menopausal women, aged 30- 45 years, with a Body Mass Index (BMI) of between 30 and 45 Kg/m2 at increased risk of breast cancer and will be identified within the regional Family History Clinic at The Prevent Breast Cancer Research Unit.
Women will be assigned to follow either eight weeks of an intermittent “2 day low calorie diet “or eight weeks of a daily low calorie diet dietary intervention. We will assess the effect s of the two different diets on fat stores in the liver, pancreas (MRI), abdomen and within the abdominal muscle. We will also compare their effects on muscle mass and metabolic rate.
The research will be carried out within The Prevent Breast Cancer Research Unit, University Hospital South Manchester, the Christies NHS Trust and the Wolfson Molecular Imaging Centre (University of Manchester) in collaboration with the Obesity and Cancer Research Group (lead: Professor Andrew Renehan), Manchester Cancer Research Centre (MCRC).
What impact will this project have?
If we can show the further benefits of The 2-Day Diet, this would confirm the effectiveness of the diet as well as it’s need, not just for people at greater risk of developing breast cancer, but for many cancers, cardiovascular diseases and diabetes.