You can’t blame it all on the genes

“I can’t help being fat, it’s in my genes!’ We hear this statement quite often but is it the whole truth?  Obesity is a major global health problem. In 2005, it was estimated that at least 400 million adults were obese (BMI > 30) world-wide. By 2015, it is estimated that the number will increase to about 700 million. Genome-wide studies have identified 12 alleles (an allele is a locus on a chromosome where the DNA is different) that are associated with increased BMI. Does the possession of one or more of these alleles sentence you to a life of obesity? Or could you influence this genetic predisposition to increased obesity risk by lifestyle changes?

Researchers from Cambridge University genotyped the 12 loci in a population-based sample of 20,430 adults from the European Prospective Investigation of Cancer (EPIC)-Norfolk cohort and assessed the influence of a physically active lifestyle on the genetic predisposition to obesity in these individuals (PLoS Med 7(8): e1000332. doi:10.1371/journal.pmed.1000332). The study showed that, in a 1.70 metre tall person, every additional BMI-increasing allele was associated with an increase in BMI equivalent to 445 gm in body weight. In physically inactive individuals, the increase was 592 gm per allele. In physically active individuals, the increase was 36% lower at 379 gm per allele. In physically inactive individuals, possession of one of these obesity-susceptibility alleles increases the obesity risk by 15.8%. However, in physically active individuals the risk is 40% less at 9.5%.

While possession of the wrong genes can predispose an individual to weight gain, the trigger for weight gain is not purely genetic. We have to provide that trigger in the form of inappropriate lifestyle choices. Eating more than we need, eating foods that are high in fat and sugars, lack of physical activity due to increasingly sedentary lifestyles are all triggers to the worldwide obesity epidemic. Becoming obese not only affects self esteem and image, it also brings with it a slew of health problems such as heart disease, hypertension, diabetes, steatohepatitis, joint problems and cancer.

The next time you are about to blame your weight gain on mother nature, perhaps you might want to think again!