Obese people age more quickly than people of normal weight, but an Austrian study found that losing weight following bariatric surgery reverses premature aging.

"Obese people are prematurely old," said lead author Dr Philipp Hohensinner, a researcher at the Medical University of Vienna. "They have an increased level of inflammation, with higher levels of inflammatory cytokines (small proteins important in cell signaling) in their fat tissue. Obese people also have shorter telomeres at the end of their chromosomes."

Telomeres are the pieces of DNA that act as protective caps on the ends of chromosomes. Chromosomes, which protect our genes, get shorter every time a cell divides. When the telomeres get very short, the cell can no longer divide and is replenished or stays in the body as an aged cell. Many studies have shown that shortened chromosomes are associated with the diseases of aging.

Previous research found that obese women had shorter telomeres compared to women with a healthy weight, which amounted to an added eight years of life.

The current study investigated whether bariatric surgery and the resulting weight loss could reverse the premature aging in obese patients.

The study included 76 obese patients who were an average age of 40. All patients had been unable to lose weight through lifestyle changes and were referred for bariatric surgery. This procedure bypasses the gastrointestinal tract and leaves only a pouch of stomach.

"Bariatric surgery drastically reduces the amount of food patients can eat. People lose around 30 to 40 percent of their whole body weight in the first year," said Dr. Hohensinner.

One year after undergoing surgery, body mass index (BMI) dropped an average of 38 percent. In addition, there were decreases in the pro-inflammatory cytokines plasminogen activator inhibitor-1 and interleukin-6, and an increase in the anti-inflammatory cytokine interleukin-10.

"The loss of a large amount of fat seems to shift the body's system from a pro-inflammatory state towards a more healthy one," said Hohensinner.

Two years after surgery, the patients' telomeres were 80 percent longer than they had been before the procedure.

"These cells are replenished over time," said Hohensinner. "The cells we examined at two years were different cells in this new post-surgery environment. They had longer telomeres and appeared younger than the cells we measured before surgery."

The researchers also evaluated telomere oxidation, which causes the telomeres to break and get shorter. They found that two years after surgery, oxidative damage on the telomeres had reduced by three-fold.

"We think the cells appear to be getting younger, with longer telomeres, because there is less breakage from telomere oxidation," he said. "Obesity, and specifically having a lot of fat tissue, seems to put the entire body under increased stress. By losing weight and therefore adipose tissue, that stress reduces, and the body becomes younger.

"This is positive news for patients who have bariatric surgery because it shows that the damage from obesity can be reversed," he said. "Surgery is the last resort for these patients and it is good to see that not only do they lose weight, but they also reduce the stress on their body and reduce the premature aging."