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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
    http://onlinelibrary.wiley.com/doi/10.1002/oby.20958/full

    Letting your imagination run wild – genetic testing for risk of weight gain

    By Susanne Meisel, on 5 April 2013

    These are exciting times for people working in genetics.  The field has become trendy.  ‘DNA’, ‘genes’ and ‘genetic code’ are no longer specialist terms, but used casually in everyday language. The media love ‘The gene for’ stories  and attributing individual differences to biology and less to environment is becoming commonplace.  I recently read an interview with a singer who explained that she could not imagine being anything else but a singer, because singing ‘was in her DNA’. If this still does not convince you: The pop band ‘Little Mix’ recently released a new song titled ‘DNA’ (http://www.youtube.com/watch?v=D3h-lLj3xv4).

    Why the fascination with genes?  To a degree, it appears to stem from the inherent assumption that our genes can give us insights into ourselves that would otherwise remain inaccessible. Although our DNA is  99.9% identical, this is not interesting – it is all about the tiny bit of difference, the bit which sets us apart and makes us unique.

    Companies have been quick to capitalise on our curiosity of what would be possible once the Human Genome was decoded.  Genetic tests for an array of traits and conditions, including those that are common and driven by lifestyle, such as obesity or heart disease, are already available over the Internet.  So far, we are not sure about the effects of giving this type of information to people. It could be that people will use it to prevent the condition. Alternatively, it could be that they become fatalistic or complacent. I have written in more detail about the current debate in a previous blogpost ( http://tinyurl.com/bve6y2m).  I hope to add some evidence to the debate by looking at the psychological and behavioural consequences of receiving genetic test feedback using obesity as an example for a very common, very complex condition.

    Because we do not know yet how people react to knowing about their genetic susceptibility to weight gain, it would be unwise to give them this information right away.  Instead, we set up an online study where people were asked to imagine their reactions to receiving a ‘higher-risk’ or an ‘average-risk’ genetic test result for weight gain. They were then asked questions on a broad range of feelings and behaviours. We included 2 sets of people, nearly 400 students, who were predominantly of healthy weight and almost as many people from the general public who were or had been overweight.

    Results showed that people in both groups reported to be more motivated to make lifestyle changes after imagining getting a ‘higher’ genetic risk result than after imagining getting an ‘average’ genetic risk result. On average, negative feelings and feelings of fatalism were anticipated to be very low and did not differ between risk scenarios. Those who were already overweight or obese were more likely to think that in comparison with an ‘average’ genetic risk result, receiving a ‘higher’ genetic risk result would offer them an explanation for their weight status.  Finally, people in both groups thought that they would be more likely to seek out information about what their result means in the ‘higher-risk’ than in the ‘average-risk’ scenario.

    These findings are good news, because they suggest that giving people feedback for susceptibility to weight gain is unlikely to have unanticipated negative effects, and may even be motivating.  Furthermore, people who are already overweight may also benefit from genetic feedback.  However, these findings may not hold up once people are actually given genetic test feedback, because they only tell us about what people think they might do – and people find it generally quite difficult to imagine to be negatively affected by an event.  The next step is now to give people ‘real’ genetic feedback for risk of weight gain to discover the effect of this type of information.

     

    Reference:

    Meisel, S. F., Walker, C., & Wardle, J. (2011). Psychological Responses to Genetic Testing for Weight Gain: A Vignette Study. Obesity (Silver Spring); 20 (3).DOI: 10.1038/oby.2011.324

     

    ”Battling against one’s biology”: Inherited behavioural susceptibility to obesity

    By Susanne Meisel, on 30 March 2012

    As mentioned in one of our previous blog posts, talking about genes in the context of obesity is often not well received.  Those discounting their role in the development of obesity often argue that, because genes have not substantially changed over the past 200 000 years, whereas obesity levels have only been soaring over the past 20 odd years (where it became possible to mass-produce cheap, tasty food in combination with a decreased need for physical activity), obesity must be due to changes in the environment, and not genetics.

    However, using this argument against the heritability of obesity is somewhat flawed, because it ignores that a condition can be dormant over a period of time until the right circumstances bring it to life.  The gardeners among you will know that many plants will adjust their growth according to their surroundings – a plant in a small pot will remain small, whereas a larger pot will allow it to grow.   This, however, does not mean that the plant loses its ability to grow larger in a smaller pot; it merely remains small because its surroundings restrict its growth.  Similarly, genes predisposing to obesity may be present in an environment where little food is available, but without the right ‘medium’ (i.e. food), this is of little consequence.  In the current environment, however, where eating opportunities are plentiful, obesity genes can express their full force.

    If obesity was resulting purely from environmental change, all individuals exposed to this change would become overweight.  Yet, this is not the case. In fact, the proportion of lean people has not substantially changed, but large people are becoming even larger.  This suggests that people respond to the food environment differently.  However, undoubtedly, to gain more weight than is healthy, food must not only be available in sufficient quantities, but one must ingest more of it than necessary.  Therefore, researchers started to look at differences in eating behaviours, such as how much we are drawn to food and how quickly we feel full, to see what is going on.

    Twins can help to untangle the influence of genes and environment on obesity, because identical twins are 100% genetically identical, whereas non-identical twins only share approximately half of their genes (like normal siblings); both, however, grow up in a very similar environment.  This means that researchers can compare identical twins’ resemblance for weight with that of non-identical twins; if genetically identical twins are more similar in a trait than non-identical twins, it is evidence for genes being responsible for the trait.

    Using twins, researchers from our department wanted to see whether genes that influence weight also influence appetite.  If the same genes that influence weight also influence appetite, it suggests that genes influence weight through their effects on appetite – i.e. individuals who inherit more avid appetites might be more susceptible to overeating in the modern food environment, and consequently  more likely to gain excessive weight.  They looked at this in infants, because infants are exclusively milk-fed, which ruled out that other factors such as preference for certain foods would influence the results.   The researchers used questionnaires to ask parents about how fast their twins fed, how easily they got full and how big their appetite was, and related the answers to the babies’ weight.   Because they used a sample of identical and non-identical twins the researchers were able to explore the extent to which appetite is heritable, and the extent to which appetite and weight are caused by the same genes.

    They found that identical twins were not only very similar in weight, but shared many more similarities in appetite than non-identical twins, suggesting a strong genetic basis to both appetite and weight.  In addition, the results  showed that a substantial proportion of the genes that are responsible for weight are also responsible for appetite, in line with the idea that genes influence weight through appetite.  These findings lend evidence to the idea that some of us are more likely to overeat in the current environment because of a larger appetite, which is ultimately driven by genes.

    These discoveries will hopefully contribute to reducing the stigma that surrounds unhealthy weight gain; because it clearly shows that those struggling with weight are in a sense ‘battling against their biology’.  This of course, does not mean that there is nothing that can be done about it; however, acknowledging these differences as real and designing strategies to ‘outsmart’ one’s genes is crucial if the battle is to be fought successfully.

     

    Article reference: http://www.ajcn.org/content/95/3/633.long

     

    Looking into the genetic crystal ball – A personal account of taking a direct-to-consumer genetic test

    By Susanne Meisel, on 25 November 2011

    There it sits, on the counter, the vial which holds the key to knowledge, everything from ancestral lineage over earwax texture to my memory capacity. My strengths and weaknesses, the key to who I am…at least in genetic terms.

    Proponents for direct to consumer genetic testing claim that a bit of spit contains everything I could possibly want to know about myself. The skeptics call it a genetic horoscope, as most results are no more accurate than traits attributed to star signs.

    In recent years, companies emerged which offer genetic testing over the internet and promise to tell you more about your health and ancestry than you ever imagined.  With a couple of mouse clicks you can order one of their test kits, spit into a collection tube, seal it, send it back and within a few weeks you receive an email containing the link to a website which reveals your risk for a myriad of traits and diseases, half of which I would have trouble spelling, let alone pronounce.

    Of course, doing a PhD in the subject calls for some self-experimentation, so my supervisor thought it would be a good idea for me to experience what this feels like … and this is how I ended up with a plastic tube full of spit.

    It took me 3 days to send it off (apologies to the poor person in the lab who has to open that stinky tube). Why did it take me so long, I wonder? I consider myself as a curious individual interested in the latest scientific discovery, open to adopt new technologies…so why the hesitation?

    I guess, because it felt like it could bring something to light which I might have happily left lurking in the dark. The 23andMe test I took reveals my risk for over 100 health conditions, some of which are quite severe, such as my risk for Huntington’s disease, Alzheimer’s or breast cancer. In addition, it shows my carrier status for various genetic diseases; my reaction to certain medications and finally personal traits such as memory capacity or the likelihood of ending up as an alcoholic. That, dear readers, is a lot of information. All at once, on one page.

    Do I even want to know all of this? Even if I know that no cure exists for most of the diseases listed? The answer is: sort of. But, at this stage, only very few gene results can give meaningful risk estimations; most give only a minute indication of any change in risk – be it for better or for worse. The problem is also that conditions with exclusively genetic cause, such as Huntington’s Chorea, are listed with conditions where the picture is more complicated (for example in obesity).  This makes it very hard to know how much meaning to attach to a single risk result. I know I would be better off taking a long and hard look at my family history, if I wanted to get an idea of which diseases may be befalling me one day.

    Nonetheless, I was incredibly curious to find out, and although my rational brain immediately told me that the results didn’t mean anything in the grander scope of things, they were all but unimportant. I felt something, and I definitely focused much more on the conditions where I was at a ‘higher risk’ than on those where I was classified as ‘average’ or ‘reduced risk’, regardless of what the actual risk estimation was.

    The companies which provide direct to consumer genetic testing take quite a risk: They are providing medical results with minimal advice for conditions that many people may never have heard of, with risk estimations that don’t mean much objectively, but nonetheless seem to have an emotional impact – there is a lot of room for misunderstanding here.

    For example, if I found out that my genetic risk of lung cancer is 6.8 % instead of the average of 6.2 %, then objectively that tells me that there is a whole host of factors other than my genes that play a role – however, because it is my personal  risk, it has some emotional meaning and in response

    1. I could do the wise thing and stop smoking- advocates of these tests hope that we are using the information that we received to change our behaviour and prevent eventual illness

    2. I could panic and ring my doctor for immediate 3 monthly check-ups – opponents of direct-to-consumer genetic testing fear that it might lead to unnecessary medical procedures

    3. I could think that I will get lung cancer anyway and smoke even more, because of it – another concern of those cautioning against direct-to-consumer genetic testing

    What will I do? What will other people do? I wouldn’t have been able to say before I took the test, because there is very little research on the subject to date. Now I know I will definitely not worry. But someone else might. It is an utterly individual experience, and there is certainly a good portion of narcissism attached.

    Will I change anything? At the moment I am doing quite a lot of the ‘right’ things anyway, like being fairly active and eating sensibly (let’s keep quiet about the drinking) – but I’d like to think that it will have an impact when I am older. I think that it can be a positive influence on one’s health, because it raises awareness of potential illness and may be a motivation to look after oneself. Would I recommend it? Yes, but only if one is aware of the shortcomings of these tests, and if there is good information available about what the result means.

     

    Despite all its criticisms, receiving those genetic results was a very unique experience, and I found out some things I am quite glad about. My eyes really are blue.  One thing, however, I didn’t look at: my genetic risk for Alzheimer’s disease. I think it would have been too disturbing to find out that I am more likely to get a severe illness for which there currently is no cure. But that was my individual choice. And that is what personalized genetic testing is all about.

     

     

    Would you get tested? Why? Why not? Let me know below or send an email to Susanne.meisel.09@ucl.ac.uk