Despite eating a "normal" diet, animals can still become obese if their ancestors were undernourished for several generations because of genetic adaptations controlling the way their bodies store fat, according to a new study.

Researchers said the potential for these changes is the reason that 70 percent of people with type 2 diabetes by 2030 will be residents of developing nations.

"People in developing countries have faced multigenerational undernutrition and are currently undergoing major lifestyle changes, contributing to an epidemic of metabolic diseases, though the underlying mechanisms remain unclear," researchers wrote in the study, published in Cell Metabolism.

Two groups of rats were studied by researchers in the study, one group eating a normal diet for 52 generations and the other being undernourished for their first 50 generations before being given a normal diet for the final two generations.

At the end of the study, the rats who'd been undernourished for 50 generations were more likely to develop diabetes and other metabolic defects because their bodies had expressed genes over time to store fat in certain ways based on their diets.

"Their adverse metabolic state was not reversed by two generations of nutrient recuperation through a normal diet," said Anandwardhan Hardikar, an associate professor at the University of Sydney, in a press release. "Instead this newly prosperous population favored storage of the excess nutrients as fat leading to increased obesity, cardiovascular disease and metabolic risk for diabetes when compared to their 'developed world' counterparts."

Hardikar said that lower B12 levels in the undernourished rats could be contributing to the higher risk factor for obesity and diabetes, and that further studies would be needed to determine if a B12 supplement could correct for the risk for metabolic diseases in future generations.