Weight loss that comes about as a result of bariatric surgery may reverse the premature ageing that is linked with obesity, a new study suggests.

Bariatric surgery is a procedure carried out on people who are obese to help them lose weight. An example of this is the insertion of a gastric band, which reduces the size of the stomach.

According to Austrian researchers, obese people are ‘prematurely old'.

"They have an increased level of inflammation, with higher levels of inflammatory cytokines (small proteins that are important in cell signalling) in their fat tissue. Obese people also have shorter telomeres at the end of their chromosomes," explained the study's lead author, Dr Philipp Hohensinner, of the Medical University of Vienna.

Telomerea are found at the end of chromosomes and their function is to protect the chromosomes from being damaged.

Over the course of a person's life, telomeres become shorter, leaving people more susceptible to cell damage and diseases such as heart disease. As a result, their length is considered a marker of a person's biological age.

Previous research found that obese women had shorter telomeres compared to women of a healthy weight. In real terms, this meant that the women of a healthy weight could expect to live an average of eight years longer than the obese women.

This latest study set out to assess whether bariatric surgery could reverse this apparent premature ageing in obese people.

It involved 76 patients with an average age of 40 and an average body mass index (BMI) of 44. A BMI of 30 or more is considered obese, while a BMI over 40 is considered severely obese.

All patients had failed to lose weight through lifestyle interventions and had been referred for bariatric surgery.

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

The researchers analysed blood samples before surgery and one and two years after surgery to compare the levels of premature ageing markers.

They found that a year after surgery, the BMI of the participants had fallen significantly, to an average of 27, which amounted to 38% of their entire body weight.

This appeared to decrease the amount of pro-inflammatory cytokines and increase the amount of anti-inflammatory cytokines in the body.

Furthermore, two years after the bariatric surgery, the patients' telomeres were 80% longer than they had been before the surgery.

The researchers also looked at a process called telomere oxidation, which causes telomeres to break and get shorter. Two years after the bariatric surgery, this type of damage had reduced three-fold.

"We think the cells appear to be getting younger, with longer telomeres, because there is less breakage from telomere oxidation. 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," Dr Hohensinner said.

He described this as ‘positive news' for people who undergo bariatric surgery ‘because it shows that the damage from obesity can be reversed'.

"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 ageing," he added.

Details of these findings were presented at the Frontiers in CardioVascular Biology (FCVB) congress in Italy, which was organised by the European Society of Cardiology.