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New research sheds light on the role of genetics in nation's obesity battle
Many people battling weight and obesity problems have expressed their frustration by saying "it's in my genes."
Now, scientific research is showing that genetic factors do have a significant role in determining whether people are thin or heavy.
Dr. David Allison, a leading obesity and genetics expert, will be the guest speaker Friday, April 22, for the 2011 Delta Omega Honor Society in Public Health Lecture Series by the Arnold School of Public Health.
His talk, titled "Obesity: A Look through the Kaleidoscope," will be held at 3:30 p.m. in Room 114 of the Public Health Research Center on Assembly Street. The event is free and open to the public.
A Distinguished Professor at the University of Alabama at Birmingham, Dr. Allison is Head of the Section on Statistical Genetics and Director of the NIH-funded Clinical Nutrition Research Center. His research interests include obesity, quantitative genetics, clinical trials and statistical and research methodology.
Dr. Allison recently shared information about his research and the role of genetics on obesity.
Question: What should the average person know about the link between obesity and genetics?
Answer: It is now well established that genetic differences among people within populations explain approximately 65 percent of the differences in how thin or heavy we are. Although it has only been in the last 25 years that scientists have come to accept this as a given, it was really obvious for nearly a century earlier. Farmers could selectively breed animals for greater or lesser degrees of fatness.
This ability to selectively breed shows a genetic influence on traits. We humans are no different.
Question: Why is it important to know this?
Answer: In the long run, we hope that knowledge of the specific genetic factors that influence obesity will help scientists to develop better treatments, to understand how obesity occurs and how it influences other health outcomes, to predict who is most susceptible to the adverse health effects of obesity, and to promote better treatment and prevention strategies. But we are not there yet.
Although we know obesity has a strong genetic component, the information does not currently provide us the ability to help many people directly. It may offer individuals some comfort to know that if they are suffering from obesity, it is -- to a large extent -- due to their genetic makeup. This does not mean that their obesity is inevitable and cannot be reversed, but it is a recognition of the difficult struggle they have had and will continue to have in reversing it.
This is not, as some people pejoratively put it "an excuse," but rather an honest recognition that there are important innate differences among us in our ability to maintain what is generally perceived to be a normal bodyweight with some achieving it easily and without effort and with others having to constantly fight against a genotype oriented toward increased body fatness.
Question: Even if genetics plays a role in obesity for some people, it's not the case for everyone. How can doctors and other healthcare professionals make the distinction? And what role does the individual have in taking steps to help their health?
Answer: Clearly individuals can and regularly do take charge of their own health, improve quality of their diet, their physical activity patterns, and other aspects of lifestyle to reduce bodyweight and/or improve health generally. It is generally only the individual who can make this decision for themselves and this is true regardless of their genetic propensity toward greater or lesser fatness.
Question: What have researchers discovered in recent years about obesity that will help children and adults in their battle against weight problems?
Answer: We are still not at the point where the genetic information we have learned is directly useful for most people. However, there is some promise on the near-term horizon. Specifically, new statistical approaches to whole genome prediction analysis may pave the way for important advances in personalized medicine.
Specifically, we know that some people who become obese suffer greatly from their obesity and have many ill health effects as a result. In contrast, other people who become obese hardly seem to suffer at all. If we could more effectively predict who is at greatest risk from the adverse health effects of obesity, we could provide those obese persons the greatest help in reducing their obesity.
We currently have work under way in our group to try and develop statistical methods for such prediction by adapting novel statistical approaches being used in the field of agriculture to predict the genetic value of plants and animals. It is too soon to tell how well this method and approach will work, but we are excited about the possibilities.
Question: What does your research cover in regard to obesity?
Answer: My own research is quite broad, spanning multiple species and multiple approaches. Very broadly speaking, I investigate in major areas. The first is the influence of body weight, body fatness, and caloric intake, as well as changes in each of those variables, on longevity. We are currently testing a number of novel hypotheses about how obesity, caloric intake, and body composition may be related to longevity, as well as developing new statistical methods to enhance such research.
My other broad area of research involves understanding the genetic and environmental influences on obesity. I am especially interested in the less commonly pursued causes of obesity, which include, but are not necessarily limited to, postulated causes such as decreased variability in ambient temperature to which humans are exposed, decreased sleep, increased cognitive demands in the workplace, increased light exposure, microbial infections, and other influences.
Finally, I spend some of my time conducting randomized, controlled trials of novel treatments for obesity and developing statistical approaches for the analysis of randomized trials and epidemiologic studies.
Question: Is there any evidence that people are making changes?
Answer: This is difficult to say. Evidence regarding what people eat and how physically active they are most often comes from self-reports, and such self-reports are well known among scientists to be of very limited quality. Therefore, our database on diet and activity patters among free-living humans is quite limited. There is some evidence in recent years that the steady increases in BMI that we have been seeing for the last quarter century have been leveling off.
It is not clear that the trends are reversing and going in the other direction, but perhaps they are no longer increasing. This could potentially suggest that the population in general is making positive changes with respect to diet and physical activity.
However, it is still early to be confident in this. In addition, data from other countries, such as Denmark, suggests that there may be pauses and lags in between periods of increased growth in population levels of obesity. At this point, we need to continue to monitor these trends and continue to look for additional ways to help people improve their diets, their physical activity patterns, their lifestyles in general, and their overall health and quality of life.
Dr. David Allison will speak at 3:30 p.m. Friday, April 22, for the Arnold School of Public Health’s 2011 Delta Omega Honor Society in Public Health Lecture Series.
