The 'Fat Gene'
On the genetics side, there's an element of inherited predisposition toward (or increased risk factor for) obesity. Researchers have identified a "fat mass and obesity associated," or FTO, gene that increases the likelihood that a given person with that gene will be obese by about 23 percent.
News about this so-called fat gene has given some overweight or obese individuals the idea that the dice are loaded and there's little point in even trying to lose weight; dieting is difficult enough without our heredity fighting against us.
However, before you throw up your arms and blame your genes for your growing girth, there's good news from a new study published in PLoS Medicine titled, "Physical Activity Attenuates the Influence of FTO Variants on Obesity Risk: A Meta-Analysis of 218,166 Adults and 19,268 Children."
The study found that the effect of the gene on weight gain is very small, only about 2 pounds. So, for example, if you carry the FTO gene and you're 20 pounds overweight, at best you can blame about 2 of them on your parents; the other 18 pounds (about 90 percent of your extra weight) are the result of your dieting and exercise habits (or lack thereof).