Common FTO gene variants may increase body fat through increased adipose tissue energy expenditure or effects on central nervous system circuits regulating food intake.

“we think it's affecting genes that do encode something and we think we know at least what one of those genes is and what I would like to see is what the consequences of these variants are on the functional activity of the system that we think is mediating the effects of these genes because I again for reasons that are quite technical I think that one of the major impacts of this gene or these variants in this gene is actually on the structure of the nervous system so I think their impact is occurring early in the development of the brain and that what it's doing is changing the circuitry slightly in a very maybe subtle way probably subtle way that favors the increased food intake that you've just described”