Food@Manchester


Manchester-born and fed: How our 5:2 diet is leading the fight against obesity and cancer

An interview with Michelle Harvie.

At least half of the UK population will be obese by 2050, according to current Government predictions.

Given the proven links between obesity, heart disease, diabetes and cancer, that’s a pretty terrifying forecast.

But it’s not all doom and gloom.

a diet that you’ve almost certainly heard of and may even have tried

There is a new diet that is helping many people to lose weight, and crucially, to keep weight off once it’s lost.

It’s a diet that you’ve almost certainly heard of and may even have tried yourself: the 5:2 or - as we prefer to call it - the two-day diet.

It’s not a fad created by the media or the brainchild of some Californian quack.

No, it was created right here, in Manchester, by myself and Professor Tony Howell on the back of eight years of thorough research and analytical testing at the Genesis Breast Cancer Prevention Centre.

Back in 2006 we discovered that weight loss could reduce the risk of women developing breast cancer. Just losing 5% of weight and keeping this off could reduce breast cancer by 25 – 40%

two consecutive days of a reduced calorie intake followed on the other five days of the week by a “normal” diet

This was an exciting breakthrough, but we knew that standard approaches to dieting with daily healthy eating diets and counting calories every day had a limited success, as people found them hard to stick to. Faced with the day in day out prospect of dieting, many people simply give up and go back to their old habits.

Our concept was simple: two consecutive days of a reduced calorie intake followed on the other five days of the week by a “normal” diet that offered an acceptable balance between excess and abstinence. Relieved of the psychological pressure of maintaining a daily diet, more women found it easier to develop healthier eating habits, lose weight and keep it off. The 2 day diet seemed to retrain their appetite and often gave people more energy.

Now we’re looking at how losing weight with the two-day diet can also help women who already have breast cancer by reducing the toxicity of their chemotherapy, making it more effective and limiting the unpleasant side effects at the same time. And our research is not just supporting breast cancer patients. We’re hoping it will soon be adopted by GPs and dieticians around the country as a key weapon in the fight against obesity.

Further afield, Manchester’s very own two-day diet has become an international phenomenon, helping thousands of people around the world to lose weight safely and effectively - something that we’re all very proud of!


Dr Michelle Harvie is a Research Dietician at the Genesis Breast Cancer Prevention Centre, based at the University Hospital South Manchester Trust. Her groundbreaking work in the prevention and treatment of women with breast cancer through the promotion of healthier lifestyles included creating the internationally renowned 5:2 diet.

Q & A

What is your specific field of research?

We have two parallel streams of research: the first focuses on the prevention of cancer and primarily breast cancer through a healthy diet and the second is looking at how we can make the treatment of breast cancer more effective through sustained weight loss. I’ve always been interested in the link between diet and cancer and I find the more I’ve studied it, the more interesting it’s become.

What led you to base your research here at the University of Manchester?

I graduated here in 1989 in biochemistry and then continued my studies with Professor Tony Howell on a PhD that looked at the diets of cancer patients, with a particular focus on why breast cancer patients often gain fat and lose muscle during treatment. Like a lot of big cities, there are quite a few people in Manchester who live unhealthy lifestyles so there’s a big pool of people to study! I’ve been very fortunate to work with some world-acclaimed oncologists and geneticists here at Manchester and with their support and guidance, I’ve been able to build up my own international reputation.

Why is food such an important issue at this point in time?

The irony is that as our knowledge about food and nutrition has improved, our eating habits have got worse. Since I began my research in this area in 1994 we’ve seen a significant increase in cancer rates and an increase in the number of diseases that are linked to people being overweight and unhealthy lifestyles. It seems like we’re finally waking up to how important these links are.

How does your research help meet this challenge?

We developed a brand new diet - the 5:2 diet or the two-day diet as we prefer to call it - as part of our research into preventing breast cancer and its recurrence with weight control.

Our randomized trials of two-day diets versus traditional daily diets showed that the two-day diet was more effective for sustained weight loss because the women in the trials found the 2 diet days very doable- and they often found they naturally wanted to eat less on the other days – a win-win situation which is why they lost more weight .

Our diet is designed from good nutritional principles. If you cut the calories down too much, and fast or don’t consume enough protein, you start to lose muscle mass, which is bad news for health and importantly will drop the metabolic rate and actually lead to weight gain.

On the diet days, we recommend a set number of protein portions - which also helps you feel more full - and a reduction in the amount of carbohydrates.

On the non-diet days, we don’t subscribe to the idea that you can eat whatever you want. If you did, the diet simply wouldn’t work!

Dieting on just two days makes people feel more confident about themselves and less likely to overeat on the other days of the week.

It also seems to retrain people’s appetite and eating patterns, something that we’ve failed to do with the daily diet approach.

We have found that 2 day dieters have big reductions in hormone levels such as linked to risk of cancer and other diseases. We also believe the 2 day diet could have additional beneficial effects, such as maintaining metabolic rates and muscle mass. We are testing this in our current genesis funded study

It’s certainly helped the women in our studies to reduce their risk of breast cancer, as well as helping lots of people around the world to lose weight.

Now we’re looking at whether losing weight can also help women who already have breast cancer by reducing the toxicity of their chemotherapy as one of a number of new applications of the two-day diet.

How important is collaboration?

It’s massively important. If I was just working on my own then it’s unlikely that people would sit up and listen so the fact that I can collaborate with some great scientists and clinicians both here in Manchester and around the world makes a huge difference.

Looking ahead, what are you most excited about?

I’m hoping that the two-day diet will have a real and meaningful impact on the growing trend of obesity and that it will be adopted by healthcare professionals in a clinical setting to manage the weight of all their patients, not just those at risk of or already suffering from cancer.

And what are you most concerned about?

My biggest concern is the ability to get funding to continue dietary research. Everyone has their own views on nutrition and those views tend to be quite deeply held so it’s often difficult to get backing for new and innovative approaches, particularly those that don’t involve investment in drugs. A lot of these drugs simply mimic what we’re doing with the promotion of healthy lifestyles plus they have side effects and considerable costs attached. We were very lucky with the support for our two-day diet research, but we had to go round the houses to get that funding.

By Bill Bows in interview with Michelle Harvie.