During Aging, Weight Increases as Lipid Turnover Decreases

Lipid turnover in the fat tissue decreases during aging and makes it easier to gain weight, even if we don't eat more or exercise less than before, according to a paper published today in Nature Medicine by researchers at Karolinska Institutet.

The scientists studied the fat cells in 54 men and women over an average period of 13 years. In that time, all subjects, regardless of whether they gained or lost weight, showed decreases in lipid turnover in the fat tissue, that is the rate at which lipid (or fat) in the fat cells is removed and stored. Those who didn't compensate for that by eating less calories gained weight by an average of 20 percent.

The team also examined lipid turnover in 41 women who underwent bariatric surgery and how the lipid turnover rate affected their ability to keep the weight off four to seven years after surgery. The result showed that only those who had a low rate before the surgery managed to increase their lipid turnover and maintain their weight loss. The researchers believe these people may have had more room to increase their lipid turnover than those who already had a high-level pre-surgery.

"The results indicate for the first time that processes in our fat tissue regulate changes in body weight during ageing in a way that is independent of other factors," says Peter Arner, one of the study's main authors. "This could open up new ways to treat obesity."

Prior studies have shown that one way to speed up the lipid turnover in the fat tissue is to exercise more. This new research supports that notion and further indicates that the long-term result of weight-loss surgery would improve if combined with increased physical activity.

"Obesity and obesity-related diseases have become a global problem," says Kirsty Spalding, another of the study's main authors. "Understanding lipid dynamics and what regulates the size of the fat mass in humans has never been more relevant."