That said, the study looked at three successive generations of rats following the original parents' generation's switch to a purposefully obesogenic diet where the diet/environment was kept constant for each successive generation. The thinking was, as per prior research, altering the original parents' environment would lead to offspring more likely to have obesity by way of something called "epigenetic inheritance". The question the researchers had was whether or not that "adipogenic" trait was carried forward in their successive offspring if the environment remained constant (and obesogenic).
According to the authors, keeping the rats' successive generations' environments constant was important because it,
"bears more relevance to the human scenario in which populations worldwide are transitioning to and have subsequently continued to experience obesogenic environments"And epigenetic inheritance is certainly a hot topic in obesity these days, with some researchers suggesting it's responsible for much of why we've been struggling with weight as a society.
Well the good news here, at least if you're a rat, is that with successive generations, each facing the same obesogenic environment, body fat decreased, caloric intake decreased, male rats' ability to convert carbohydrates to body fat decreased, lean mass increased, as did the rats' ability to convert protein to lean mass.
Until I saw this study, everything I'd read regarding epigenetics and obesity had been doom and gloom. Here's hoping that this is one rat study that does point to some hope for humans, as we, like these rats, over the course of our past few generations, have seen our diets change from grain based unrefined ones, to ones rich in refined-ingredients, sugar, and fats.
(and these great graphics - they all come from Nestlé who sees epigenetic research as something worthy of investment)