If our parents are overweight, is it more likely that we are destined to be overweight too? It sure seems that way sometimes. However, like most other health phenomena, it's much more complicated than that.
Let's go back in time about ten thousand years. When human beings were basically hunters and gatherers, it would not be uncommon to go long periods without eating. Even way past that era, when man relied on farming and was a more social and civilized species, there were frequently long periods of famine and starvation. If you subscribe to the "survival of the fittest" theory, those individuals whose genes were well programmed to conserve energy, store it as fat, and survive, were the ones who were able to procreate and, hence, we as their descendants are also programmed to conserve energy and store it as fat. The problem today, is that in many industrialized developed countries, food is abundant. When was the last time you were worried about where your next meal was coming from? Couple the abundance of food with our bodies being programmed to store as much as it can and you have a recipe for - you guessed it- obesity.
So, at least as a species, it would seem that there is probably some genetics at work that would predispose toward obesity. But that's only part of the story. If that's the case, then why is obesity so variable between developed nations? Why is there not an obesity epidemic in Italy or France? Don't they have the best, most abundant, high calorie foods in the world?
Then there are families who tend to be overweight. You've seen them. Mom, Dad and kids are all obese. Were those kids doomed to be obese? Maybe. It is argued that there is some tendency in individual families toward obesity. While the individual genes have not been isolated, scientists believe they may be getting close. But just as was the case for the species, there are many inconsistencies in families. There are many individuals who are normal weight, but have obese parents and siblings and vice versa. Could it also be that families where obesity is rampant have poor eating habits? Perhaps obese parents are more likely to feed their kids high calorie foods, not encourage exercise, and, hence, you get overweight kids.
The bottom line is that it is probably a little bit of all those variables and we are just beginning to understand some of them- but there is much more research to be done. Nature vs. nurture is one of the most heated debates, not only as relates to obesity, but with other illnesses such as coronary artery disease, hypertension, diabetes and psychiatric disorders. Until there is more clarity about the topic, the rules remain the same: eat a low fat high fiber diet rich in fruits, vegetables and whole grains, exercise regularly and see your primary care provider on a regular basis.
Regardless of nature vs. nurture, you'll be better off, and feel healthier in the process.