Washington, Mar 13 : Researchers at University of Helsinki and the National Public Health Institute have revealed that obesity leads to poor functioning of the mitochondria, which is the principle energy source of cells.
They examined 650 pairs of Finnish twins born between the years 1975 and 1979 and identified 18 pairs that at the age of 25 had developed more than a 10 kg (22 lb) difference in weight.
The body composition and metabolism of 14 of these pairs was carefully studied and a sample of their fat was also obtained.
The research used a gene-chip technology that enabled the scientists to measure the activity of all human genes.
"Identical twins share all the same genes and almost always are also identical in weight. Studying identical twins that do differ in weight is the best approach we have to get at the mechanisms involved in the interplay between genes and environment that result in obesity", said Kirsi Pietilainen research scientist from the department of Public Health at the University of Helsinki, Finland.
The results showed that the fat cells of the obese twins contained fewer copies of the DNA located in mitochondria. This DNA contains the instructions for energy use by the cell.
"If one were to compare this cellular power plant with a car engine, it could be said that the engine of the fat individual is less efficient", said Pietilainen added.
The mitochondrion dysfunction decreases branched-chain amino acids and the resultant increased concentration in the blood, was directly associated with pre-diabetic changes, fattening of the liver and the excessive release of insulin by the pancreas.
"By employing a genomewide method, biostatistics and the unique set-up of these identical twins, we were able to uncover new mechanisms behind obesity and the early diabetic changes in the metabolism of the fat twins said Jussi Naukkarinen, a scientist at the department of Molecular Medicine, National Public Health Institute of Finland.
The research appears in the latest edition of the science journal PLoS-Medicine.