If we want to help people change their eating behaviours, we need to start talking to them in terms of food rather than nutrients

16 April 2015

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Professor Susan Jebb looks at the psychology of why we overeat, and what we can do about it.

'We’ve all got what I call an ancient physiology. We evolved in a world where food was scarce and the effort to get that food was pretty enormous, so everybody stayed thin. But in today’s modern western world there is more than enough food available.'

Professor Susan Jebb is explaining her research into behavioural medicine, looking at why people eat too much, how to stop this and why fad diets are counterproductive.

'People are assaulted by food at every turn, and we’re biologically programmed to see food and eat it because there might be a famine round the corner. Now, famines don't happen in Oxford very much, but our biology hasn’t caught up with that so we’re stuck with a biological system which is ill equipped to handle the modern food environment.

'Since we can no longer just rely on our biology to control our weight, most people needsome conscious control strategy. Some people seem to do this naturally, even unconsciously, but other people need to learn to do this. So my work looks at whether we can teach people who struggle with their weight some of the strategies people who seem to successfully manage their weight do innately.'

Can you expand on what effective strategies you've come across?

'On one side there are very effective major operations like bariatric surgery. This forces you to change your life and clearly people lose a huge amount of weight. But that is only suitable for a very small number of people. What I’m interested in is much moremodest weight loss, but done in a way that is appropriate for millions and millions of people, and so can bring huge public health gains.

'For example, one trial that’s now complete shows that if your doctor refers you to one of the commercial weight-loss groups, like WeightWatchers or Slimming World, people lose (on average) twice as much weight than people who are treated by the practice nurse – and its cheaper for the NHS too. But this won't suit everybody, so we need a range of effective interventions so that the doctor will be able to have a conversation about which of these options might suit individual patients best, effectively tailoring the treatment they offer.'

What's your standpoint on the amount of conflicting information on fad diets or celebrity diets? Do you think it’s more of an issue than it used to be because of the internet?

'It’s certainly a huge problem. There is greater diversity of advice than there was, and news of the latest diet fad travels quicker than ever before, but it has always been present. I think it is incredibly unhelpful. The frustrating thing is that the general advice – eat less saturated fat, eat less salt, eat less sugar, eat more fruit and veg – has remained pretty constant. If you look at the authoritative, expert opinion from the World Health Organization or the UK Scientific Advisory Committee on Nutrition, it’s been amazingly consistent. Those bodies produce worthy (but relatively dull) reports while individuals publicise far more exciting, anecdotal stories promising to transform your life. It’s not surprising the latter appeal to people – but when it fails, they lose a bit more confidence in their ability to manage their weight successfully.

'One of the things we've started to do is to talk about food rather than nutrients. Nutritionists think in terms of nutrients: fat and sugar, protein, iron and calcium. But when you're talking to people about what they're buying at the supermarket, they think of it in terms of foods, they don’t go and buy 30% fat, 6g of salt. They go with a shopping list which has food on it. I think as nutritionists we’ve got to start talking to people in terms of foods, not nutrients, if we want to help them change their eating behaviour. We need to get back to an emphasis on the core foods in the diet – ingredients – and re-establish the principle that foods like processed meats, biscuits, cakes, confectionery, sugary drinks and alcohol should be occasional, not every day, items. That will help cut calories, saturated fat, sugar and salt – all in one go.'

What do you think about health apps and free calorie and exercise trackers? Do you think they are helpful?

'I think they probably are helpful, and certainly for some people they are very helpful. There’s a good research base that says that if you monitor your behaviours, it can help you to change those behaviours.

'So diaries are very helpful, and I think apps are just the modern way we use to track all kinds of things: whether it's tracking phone numbers or how many steps we’ve done today. There is some research evidence that suggests the use of these apps is associated with modest weight loss. Alone they may not be sufficient, but they’re a useful part of the mix, especially for people trying to self-manage their weight. It’s important to remember that we’re not looking for "the one thing", we’re looking for a range of strategies which are suitable for different people or things each person can pick and mix and put together into a plan that works for them.'

'This kind of thinking has led to a new stream of research focused on self-management of weight that one of my DPhil students is working on. Most of what we know about how people lose weight comes from clinical trials. The truth is that, in trials, we often get a very particular kind of person, not necessarily the average person, and we very often – for obesity trials – get people who have tried and failed many many times to lose weight.

'As we’ve seen, within the health service we’re currently not very good at helping people manage weight; most people don’t even think about going to their doctor to help them lose weight. Instead, a lot of people are trying to manage their weight themselves, without professional support. So the question is what do they do? And we don’t really know. Recently, together with my colleague Paul Aveyard, I’ve done a big piece of work to try and identify a whole range of behavioural strategies that people might use to manage their weight and we’ve now developed an online questionnaire: OxFAB (the Oxford Food and Activities Behaviours). We’re looking to recruit as many people as possible who are trying to manage their weight to tell us what they do. And what we’d most like is for them to continue to tell us what they're doing intermittently over the next few months or ideally a whole year. We’ll ask them each time they log in to tell us their weight, and then there will be 10 multiple choice questions.

'We hope to build up a picture of what the nation is doing to lose weight, and – ultimately – what works. And what’s really crucial to this, and why we really want the public to join us in this, is that we want to understand what doesn't work too and what goes wrong. So over time we can build up a picture of what’s going on, the strategies associated with success, and those that don’t seem to work.'

Susan Jebb delivered the Oxford London Lecture 2015 – 'Knowledge, Nudge and Nanny: Opportunities to Improve the Nation's Diet' – on March 17.

This opinion piece reflects the views of the author, and does not necessarily reflect the position of the Oxford Martin School or the University of Oxford. Any errors or omissions are those of the author.