A diet high in carbohydrates can lead to obesity in some patients, according to a study

Researchers have identified a frequent DNA mutation in animals that could explain why a high carbohydrate diet induces obesity and diabetes in some, but not in others. The study, published in the journal PLOS Genetics, showed a surprising difference between two groups of fruit flies when they fed on a diet alternately rich in protein and carbohydrates.

Fruit fly larvae with a noted mutation in mitochondrial DNA (mtDNA) showed a marked increase in their development when they ate a diet rich in banana carbohydrates, but stagnated under a high protein diet passion fruit, reported the study cited by the agency.

Conversely, fruit fly larvae without this mutation thrived due to the high-protein diet, but lost frequency when they were in the form of carbohydrates, the report said.

The six-year collaborative study conducted by Australian, American and Spanish researchers challenged the neutral theory of molecular evolution in which species changes at the molecular level are random, are not caused by natural selection and provide no advantage or disadvantage to the species.

According to lead author Bill Ballard of the University of New South Wales, research was a rare demonstration of positive selection at work in evolution.

Given that humans share 75% of the same genes as fruit flies and that they own the same mtDNA genes, it is likely, according to the study, that the same mutation inherited from the Human mtDNA can metabolize carbohydrates in the same way.

"But, the news is not all bad for the carriers of the mutation," Ballard said.

"You'll need to manage your carbohydrate intake when you're younger, but if you're unfortunate enough to develop Parkinson's disease, a high carbohydrate diet will help you maintain your weight," Ballard added.