Dieting Living

N&S: Given the new evidence, is it wrong for doctors to immediately suggest medication for type 2 diabetics or pre-diabetics without suggesting intermittent fasting?

MM: I’m surprised by how many doctors haven’t heard of this approach. I think it’s wrong if they don’t look into it, or don’t at least suggest patients investigate it. There’s a fear patients will feel offended if their weight is mentioned, but actually they generally don’t.

N&S: A couple of women have told me that, when they were obese, their GPs never brought up their weight. Both wonder whether that’s because their doctors were overweight themselves. Another woman told her doctor she’d reversed her pre-diabetes [raised blood sugars] through 5:2, and the doctor didn’t show any interest.

MM: I’m surprised [the latter GP] wasn’t curious, because if a patient transformed themselves, I’d want to know how. And do you really want advice about weight loss from someone with weight issues? But please, do tell your doctors about 5:2 – that’s how these things often spread.

N&S: Dementia is expected to affect 150 million people by 2050. It’s as yet unproven that 5:2 could help prevent it?

MM: Frankly, we’re waiting on US neuroscience professor Mark Mattson’s current study to see if 5:2 can protect and boost the brains of people who are at increased risk of developing dementia. He says interim results are encouraging. His findings are expected to be out later this year. He’d previously done animal studies that show intermittent fasting can help combat memory loss and delay dementia.

N&S: You write that 5:2 can help prevent cancer, because carrying too much fat or having high insulin levels are risk factors for cancer. What if you already have cancer?

MM: It’s early days with research on that. But Dr Valter Longo, a human-ageing expert, found that time-restricted eating seemed to have a significant impact on the risk of breast cancer recurrence. He believes fasting has the potential to delay ageing and prevent the onset of diseases such as cancer and heart disease. On his “Fasting Mimicking Diet” [FMD], people eat 800 calories a day for a fixed number of consecutive days, mainly vegetables, olive oil and nuts. A dozen clinical trials worldwide are looking at FMD’s effect on various conditions, including breast cancer in women who had already had chemo.

N&S: How might 5:2 improve your heart health?

MM: First, by helping you lose weight. Second, by improving your insulin sensitivity. And a small study showed 5:2 had a significantly bigger impact on blood pressure than losing weight by another method. Watch this space.

N&S: When asked about intermittent fasting, Dr Fredrik Karpe from the Oxford Centre for Diabetes, Endocrinology and Metabolism said it’s “very important to critically investigate health plans for interventions giving great promises”. So many experts are still sceptical about intermittent fasting.

MM: I’m very sceptical by nature. But scientists have critically investigated all this – and still are. I sometimes collaborate on a few small studies. Mainly, though, I weigh up various claims and studies. People get understandably confused about conflicting evidence so, in the book, I explain different types of studies and the most reliable ones – particularly randomised, controlled trials. Government advice actually ranks amongst the weakest evidence. And I always look at, for instance, how big the trial is, who conducted it, who funded it, etcetera. Plus, I acknowledge gaps in scientific knowledge, and very much hope others will fill those gaps.

N&S: Back to the practical stuff. You’ve included lots of tips for doing 5:2, such as talking to others about the approach, writing things down, etcetera. How important are psychological techniques to success?

MM: Do your psychological techniques really matter that much if you feel starving? The practical steps are most important. For instance, actually doing the rapid weight loss stage will help change hunger hormones and suppress your appetite. However, psychology is clearly important regarding things like doing 5:2 with others, having clear goals, practising mindfulness, managing stress, and trying to sleep well.

N&S: If it’s too hard, you say take a break?

MM: Yes. Perhaps try intermittent dieting. It seems counter-intuitive but the Australian MATADOR study’s small trial of obese men showed “two weeks on, two weeks off” was beneficial. The intermittent dieters lost – and kept off – more weight than men who dieted throughout. Why? Perhaps it counters dieting fatigue.

N&S: Plus everyone on a diet needs breaks, especially over the Christmas season! You also say that, if you find 5:2 difficult, try 2:5 where you eat 800 calories a day during the week and don’t fast on weekends. That sounds much harder than 5:2.

MM: I’m being pragmatic. I’m providing a toolkit you can dip into to suit your needs. I think being overly prescriptive is unhelpful. For instance, it doesn’t matter if you’re 50 or 100 calories over or under.

N&S: On weekdays, my friend eats 1100 calories and exercises, then on the weekend eats junk food and drinks a fair bit of alcohol. Is that bad for her?

MM: Our ancestors had long periods when they wouldn’t eat much, and occasionally gorge, but there are no particular studies on this. Is she a decent weight, sleeping okay, and are her cholesterol and blood sugars under control?

N&S: Yes, and she’s got a body like Charlize Theron’s.  

MM: I wouldn’t knock her approach then!  

N&S: Should people of a healthy weight do 5:2 for health benefits?

MM: The honest truth is I don’t know. There’s some evidence it can benefit slim people, but right now I’m reluctant to suggest it. I’ve just been talking to researchers about doing a study looking at healthy people on the 5:2 diet. We just need to find funding, because slim people are not any health authority’s priority.

N&S: In the book, you note that people with certain health conditions, etcetera, shouldn’t do 5:2, or should consult their doctor. And people who once had eating disorders shouldn’t do it?

MM: I say that based on caution, not on science. One small study showed that people with current or past eating disorders actually do better on intermittent fasting, but I don’t want to put anybody at risk, because as a doctor I’ve sworn to “first, do no harm”.

N&S: You do a lot. Do you overwork yourself?

MM: I write books relatively fast but, before that, I collect data, studies, people’s stories, and talk to experts. I haven’t totted up my hours, but, blimey, I probably should slow down a bit.

N&S: Has anyone asked you if you’re just in it for book sales?

MM: Regularly. Mainly online. When one person asked that online, I replied “It’s all free online”, in my articles, and there’s a website for each book. But some people prefer something they can hold and flick through. Money has never been my main motivation. I just really want people to know this stuff.

This article was first published in the February 2019 issue of North & South.

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