Obesity Genes?

So does obesity occur as a consequence of family inheritance or genetics? You know, it's a really interesting question, isn't it? There's a big controversy about that. And it seems like more and more we're trying to pin stuff on the genes, on our heritage. Like, we somehow never had a chance to fill out an application card. We were just the unlucky recipient of bad news. So what is a real story about genes and obesity? Is there a gene that causes obesity? I think the answer is no, there is not a gene that causes obesity. There are many genetic characteristics that relate to the onset of obesity, but there is not a gene that causes obesity directly. Now, why do we know that? Well, there is a very interesting study that was just published in the December period of 2009 in which the investigators were looking at the epigenetic marks on the genome and how those regulated the transcription of the genetic message from our book of life, our inheritance into our structure and function, meaning into our metabolism. And in this particular paper published in the American Journal of Clinical Nutrition, what they reported is that there were individuals who had what you call resistance to caloric restriction or weight loss that were obese. And then they had those individuals who were equally overweight who on a caloric restricted diet, had significant response by lowering their weight. So you might say, what's the difference between the two? And. And what was found is that the epigenetic marks on the genome between the two groups was different, meaning the way the genes were being regulated in their expression, not the genes in and of themselves, but rather their regulation patterns. Now, you might say, well, what puts these marks on the genome? How do you get these different epigenetic marks? And some of those epigenetic marks are regulated by environmental exposures that could be things like diet and exercise patterns and environmental toxins and things that might have occurred even in utero that create a mark on the genome that allows for either the expression of certain things or the lack of expression of certain things, and ultimately appears in a metabolism that later translates into what we see as obesity. Now, why is this an interesting observation? It's an interesting observation because if you look at identical twins concordance studies and ask the question, do identical twins get the same degree of obesity as they grow older? The answer is that there's an association between the two twins, but there's not a statistically significant concordance. In fact, there's a discordance in the appearance in identical twins of obesity as they grow to be adults. It's a very loose association. So if we said that obesity was genetic. How could you have this difference between identical twins? And the answer is that if you look at the epigenome of those identical twins, you'll find based on different environments that they both experience, that they have different epigenetic marks, methylation patterns on their genome that regulates the expression of their genes. Now, the good news for us when we hear this is that we can regulate some of the experiences in our life that ultimately influence in how genes are expressed. So that this is not just a hardwired principle of obesity. And in fact, those genes that are regulated, according to the study, that relate to obesity are genes that have to do with the control of stress response and insulin signaling and inflammation response. Now, isn't that interesting, rather than just being too many calories, what we're saying, it may be events in the environment or in life that create different patterns of regulation of gene expression, which are modifiable by changing one's lifestyle. Exposure to toxins, reducing stress, reducing inflammation that ultimately can help regulate things like appetite, thermogenesis and body weight. So it's not just you have the parents that gave you obesity, It's a whole complex array of exposures that ultimately expresses itself through alter gene expression into the obese model. This opens the door for extraordinary opportunities for creating new and more effective programs for weight management than just calorie restriction alone.