This is really interesting. It concerns a study in Science Translational Medicine that looked at DNA methylation and body mass. From Science Daily:
The team used BMI data provided by Iceland’s AGES-Reykjavik study, which archives detailed information over time about that isolated nation’s population, including body compositions and metabolic regulations. “We found a high statistical significance between 13 of these VMRs and body mass index,” Fallin says. “The level of methylation at these VMRs is, in fact, related to the person’s weight.”
The researchers focused their search on the epigenetic mark known as DNA methylation because this chemical change in DNA involves the addition of a methyl (a carbon-and-3-hydrogen atom) group, which, although not contained in the DNA sequence itself, controls when and how genes are turned on and off. Such “switches” signal cells in the body that share the same DNA to assume different functions or forms.
Overall, the team measured DNA methylation levels of 4.5 million selected sites genome-wide in the Iceland DNA samples that were taken 11 years apart, from 74 individuals, ultimately tracking down an array of genes associated with body mass index.