Weight, cancer and the 2 day diet

Dr Michelle HarvieThis is the third in a series of four blog posts that explore key research topics from our recent conference: Obesity, physical activity and cancer.  

Dr Michelle Harvie is a research dietitian from the Genesis Breast Cancer Prevention Centre, University Hospital South Manchester Trust. Her research covers optimum diet and exercise strategies to prevent breast cancer and its recurrence.

One of the biggest threats to a person’s health is putting on weight as they get older. In the UK the average person will gain around 14 pounds (7 kg) as they age with many gaining more than this. A bit of extra weight may stop us looking older by padding out wrinkles, but extra weight has major effects within our cells which can lead to the development and spread of cancer, as well as many other diseases.

The weighty problem

Being overweight is not just bad for health. At 42 pounds of weight gain, breast cancer risk doubles, heart disease risk triples and a person is 12 times more likely to get diabetes. The problem is compounded by the fact that once the weight is on, losing it is a challenge. Typically only 20-40% of people who try to lose weight are successful in the short term and many regain the weight they have lost.

Evidence-based weight loss

The best weight loss diet to follow for reducing cancer risk is the diet that a person can successfully keep. Some find that they can limit their calorie intake better when the low calorie diet includes plenty of filling protein foods (including white and oily fish, seafood, lean meat, chicken, and eggs), low-fat dairy foods and plenty of vegetables, some fruit and high fibre. Others find they can lose weight by following a low-fat diet. Research has shown that heavier women who lose at least 5-15% of their weight reduce their risk of breast cancer by 20-40%.

2 day diet

We have seen weight loss success with an “intermittent diet” approach called the 2 day diet. It involves two days of intense dieting with a low carb diet and 5 days of normal unrestricted healthy eating each week, which a lot of people seem to find easier to keep to, than the daily grind of dieting every day. We tested the 2 day diet compared with daily calorie controlled healthy eating in a clinical trial. The findings were published in the British Journal of Nutrition on the day I presented the results of the trial at the WCRF/IASO conference.

We found that 65% of the 2 day dieters successfully lost weight compared with 40% of the daily dieters. The 2 day dieters lost nearly twice as much fat – 3.7kg compared with 2.0 kg in 3 months. They also had greater reductions in insulin resistance, which is key for reducing risk of breast cancer, and potentially six other weight-related cancers, diabetes, heart disease and dementia.

In February, we published the 2 day diet book which explains how the diet works and describes its potential benefits. The next step is to see how the 2 day diet affects someone with cancer. We are currently researching breast cancer patients going through adjuvant chemotherapy treatment and the 2 day diet to see if there is any impact on their health.