Are you clueless as to why your best friend eats whatever she wants and still fits into a skimpy dress and you, on the other hand, gain five pounds by just looking at a chocolate cake? Well, the culprit behind this conspiracy is your genetic makeup.
According to a new study by Tel Aviv University researchers, a woman's waistline may have less to do with rigorous exercise and abstaining from sweets than it does with the genes of her parents.
The team has determined that thinness -- like your smile or the color of your eyes -- is an inheritable trait.
In the study, Prof. Gregory Livshits from the Sackler Faculty of Medicine at Tel Aviv University and colleagues from King's College in London have found a scientific link between the lean body mass of a woman and her genes.
"The bad news is that many of our physical features, including our weight, are dependent on our genes. The good news is that women still have an opportunity to go against their genetic constitution and do something about it," said Livshits.
Until now, scientists were not sure to what extent environmental influences and genetics played a role in a woman's body size. When controlling for the variance of age, the differences in womens' body sizes can be predicted in the genes more than 50 percent of the time, the researchers found.
In the study more than 3,000 middle-aged women who belonged to either an identical or fraternal twin pair were examined.
Livshits measured the volunteers' "total lean mass", one of the three major components of body weight, and compared it to markers in their genes.
Those without the lean genes, however, will always find it harder to stay slim, predicts Prof. Livshits.
The study is published in the Journal of Clinical Endocrinology and metabolism.
