‘Health Chatter’: Research Department of Behavioural Science and Health Blog
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    Can genetic feedback for risk of obesity prompt people to take action to prevent weight gain?

    By Susanne Meisel, on 16 February 2015

    Finally, the results of my randomized controlled trial are in.

    Just to recap, the question I tried to answer was whether knowing that having a gene related to obesity (FTO) would prompt people to take action to prevent weight gain. I tried to answer this using the ‘gold-standard’ method for this kind of question: The randomised controlled trial. I randomly (by chance) assigned over 1,000 students from UCL to one of two groups. One group received a leaflet with seven tips which would help them to prevent weight gain. The leaflet was based on Habit Theory (more about this here). The other group received the same leaflet, plus obesity gene feedback for one gene (FTO) which told them whether they were at ‘higher’ (AT/AA variant) or ‘lower’ (TT variant) genetic risk for weight gain. I found out their genetic risk using DNA from their saliva (they all had to be willing to spit into a tube!).

    One month later I sent both groups a questionnaire asking about their intentions to prevent weight gain, and any activities they were engaged in relating to weight gain prevention (e.g. eating slowly, controlling portion size, avoiding snacks, avoiding sweet drinks, exercising). They also completed a measure about their readiness to control their weight based on the stage of change theory.

    Although only 279 participants responded to my questionnaire, the study had still sufficient statistical ‘power’ to draw some meaningful conclusions. We statistically controlled for factors which could potentially explain differences between groups; in this case age, gender and BMI.

    Earlier studies have shown that genetic feedback can influence behaviour change intentions, regardless of whether the actual result is ‘low’ or ‘high’ risk. This might be because the results give personal feedback, which may itself be motivating. This is why we thought that gene feedback (vs. no feedback) would have an effect on people. And we were right – participants who received genetic feedback in addition to their weight control leaflet were more likely to think about taking some action to prevent weight gain. In particular, people who were already overweight (BMI < 25kg/m2) and received genetic feedback were more likely to report that they had started to do something to prevent weight gain than overweight people who did not receive gene feedback.

    We then looked at differences between ‘higher risk’, ‘lower risk’, and ‘no feedback’ groups. Participants who received a ‘higher’ genetic risk result were more likely to report that they were thinking about doing something to control weight gain, or that they had started than people who received ‘no feedback’. There was a small difference between people who had ‘higher’ and ‘lower’ genetic risk results. Importantly, people who got ‘lower risk’ results were just as likely to think about preventing weight gain than those receiving ‘no feedback’. However, when we looked at whether people had actually followed the weight gain prevention behaviours outlined in the leaflet, there was virtually no difference between groups; most people were not following any of the behaviours despite their intentions.

    This is the first trial that has had enough participants to show any group differences with some certainty. It also aimed to show effects in a ‘real world’ scenario, with young, healthy people who were largely unaware of their genetic risk. However it also had some very important weaknesses.

    We did not assess people’s weight control intentions when they enrolled in the study because it would logistically have been quite challenging, so we couldn’t see if people’s intentions had changed. We also used only one question to make assumptions about their weight control intention. This is not such a good idea, because people sometimes give random answers, and self-report has its own problems – in hindsight it would have been better to use more questions because that allows us to check whether people answer consistently. Another limitation was that we could not have a ‘no treatment’ control group who received neither leaflet nor gene feedback. This was mainly because our study used lots of first year students who all lived in halls together; therefore, there would have been a high chance that people assigned to a ‘control group’ would have read the leaflet anyway. In addition, lots of people did not return the questionnaire. Although we expected this, it limits what we can actually say about how most students would react. People were more likely to enrol in the study if they were not overweight, and were less likely to answer the questionnaire if they were overweight at the start of the study. This means that our results may be different for these students compared to the wider student population, but we don’t know for sure. Lastly, and perhaps most importantly, I only chose to give them feedback on one (albeit well-established) obesity gene – although we know that there are hundreds of genes which influence body weight. This means that it might not be very meaningful for an individual to know whether or not they have just one of these genes – they may have many others. However, I was mainly interested whether gene feedback could ‘in principle’ be used to help people starting to prevent weight gain early, or whether it had any negative effects.

    What to make of this? The study showed that FTO feedback can influence weight gain prevention intentions, but has no effect on actual behaviour. Sadly, showing that interventions change intentions but not behaviour is common in behaviour change research. In fact, it is so common that it has a name: The ‘intention-behaviour-gap’. I am sure that most people will be familiar with the concept: You really want to do something (i.e. going to the gym, or cleaning the bathroom), but then, for one reason or another, you fail to follow through with it. In that sense, findings from the study are in good company, since lots of other studies have shown similar things, be it on the effects of genetic test feedback, or on other topics. Unfortunately, researchers are as yet not very good in explaining how to bridge the ‘intention-behaviour-gap’. This is why we thought that genetic test feedback could be a novel way – especially since it is very compelling and rational to assume that once a person knows about their elevated risk for a condition, that they would take steps to prevent it. However, as it is so often the case with human behaviour, it seems that it is not so straightforward. A more optimistic explanation is that participants did not feel the need to act on their results at this point in time – after all, most had a healthy weight – but would keep the results in mind and take action should they gain weight. Since genetic testing for common, complex conditions is still relatively novel, data on the long-term behavioural effects is still lacking.

    The good news is that a ‘lower’ risk result did not result in ‘complacency’ – the false assumption that weight gain is not possible with a ‘lower’ FTO gene result. People seem to have a pretty good idea that many genes, and the environment, act together to influence weight gain, so regardless of their result they were motivated to think about preventing weight gain as a consequence of getting feedback.

    It will now be important to find out how we can get better at communicating gene results to people, so they may have some impact on behaviour –genomics is undoubtedly here to stay, so this will be an important task for the future.
    Article reference: Meisel SF, Beeken RJ., van Jaarsveld CHM., & Wardle J Genetic susceptibility testing and readiness to control weight: results from a randomized controlled trial in university students. Obesity, 23, 2, 305-312. DOI: 10.1002/oby.20958

    What goes up, must come down?

    By Samuel Smith, on 8 September 2011

    Plans to complete a Bowel Cancer Screening test reduce after exposure to the nitty gritty of the test

    We all make plans to do things that are good for us, whether it is going for the Sunday morning jog, eating an extra spoonful of greens or saying no to that second (third or fourth!) drink in the pub. The problem is, when the time comes to actually doing whatever it is we’ve been promising ourselves and others to do, all those good intentions seem to disappear as quickly as they arrived.  For the runners among you that have woken only to be faced with a dark and drizzly January morning, you will know what it is that I’m talking about.

    So why is it that some people are able to overcome hurdles like the miserable weather, the unappealing sight boiled cabbage and the luring temptation of that extra glass of bubbly? Here at the HBRC we are particularly interested in attempting to answer that question by researching how the perception of time influences people’s behaviour. Some people are always looking towards the future and always want to be prepared for what is to come. Others just want to live for the moment and prefer not to think about what could be round the corner. Interestingly, this appears to be a relatively stable personality characteristic and it is linked to how we feel about behaving in certain ways.

    We have recently shown how plans to complete a bowel cancer screening test are affected by time perceptions. Completing a bowel cancer screening kit requires overcoming some pretty immediate obstacles (handling faeces being the most obvious to spring to mind). In addition, the benefits of doing the test won’t be experienced for at least one month (when you hopefully receive a reassuring all-clear letter), or worse, in several years’ time (when you have successfully lived for five years after your bowel cancer treatment). The question we wanted to answer was whether the same people that are able to get out of bed on a cold January morning ready for a 5 mile run, are better able to overcome the short term obstacles of a bowel cancer screening test. In other words, is the ability to look towards the future influencing decisions to complete a bowel cancer screening kit?

    We presented some snippets of information to over 200 volunteer middle aged adults (i.e. the group approaching screening age) and asked them after each statement to report ‘how likely it is that you would take part in the screening programme’ (see box 1 for the statements we showed people). Our findings showed how certain parts of the screening programme (e.g. completing it at home) were appreciated, and after finding this out the volunteers increased the strength of their plans. However, once participants were gradually informed about the nitty gritty of the test, people started to waiver. Motivation rapidly declined once people realised they had to collect a sample of faeces and hit a second low when they were informed that the test requires this to be done three times.

    Box 1 – Description of the test
    1. The NHS has introduced a screening test for men and women of a similar age group
    2. This test can detect colorectal cancer and pre-cancerous signs of colorectal cancer
    3. This test is self-administered in your own home
    4. This test provides a simple way for you to collect small samples of your bowel motions
    5. This test involves you collecting your stools in a plastic tub and sampling them for tiny amounts of blood
    6. This test involves smearing a sample of faeces onto the test kit using a cardboard stick
    7. The test involves sampling three separate bowel movements within 14 days
    8. Pictorial description of the test







    Perhaps most interestingly is that people that prefer to live for the moment were more put off by completing it three times and by some photos explaining how to complete the test kit. This enables us to pinpoint the exact stage at which motivation is reduced the most, allowing us to intervene and help people overcome these obstacles.  While this is an exciting finding (even if we do say so ourselves!), it doesn’t explain why those who prefer to stay in the present reduce their motivation faster than others. Is it because they were more put off by the short term obstacles that might affect their short term plans? Or were they just less able to see how beneficial it might be for them in the future? Our analysis seems to suggest that as always, it might be a bit of both. So back to work it is for us, but not before that five mile run I told you about. Anyone?


    Von Wagner, C., Good, A., Smith, S. G., Wardle, J. (in press) Responses to procedural information about colorectal screening using Faecal Occult Blood testing: the role of consideration of future consequences. Health Expectations. DOI: 10.1111/j.1369-7625.2011.00675.x


    Sam (Samuel.smith@ucl.ac.uk)