We All Gain Weight When We Age, And This Study Explains Why

We age, we gain weight. That has always been the way it is, at least for most of us. New research at Karolinska Institutet in Sweden tells us why: Lipid turnover in fat tissue decreases during ageing and makes it easier to gain weight, even if we have always been eating and exercising the same amount.

Over an average of 13 years, scientists observed the fat cells of 54 men and women. Regardless of whether they gained or lost weight, their fat tissue experienced a slowing in lipid turnover. Lipid turnover refers to the rate at which that fat in fat cells are removed and stored. Subjects that did not account for this slower turnover rate by consuming less energy gained weight by an average of 20 percent, according to the study which was done in collaboration with researchers at Uppsala University in Sweden and University of Lyon in France.

41 women who underwent weight loss surgery were also examined for the effect of lipid turnover rate in keeping away weight gain four to seven years after surgery. It was found that these women were only able to maintain their weight loss if prior to surgery, they had a low lipid turnover which they managed to raise post-surgery. Researchers believe that these people may have had more potential 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, professor at the Department of Medicine in Huddinge at Karolinska Institutet and one of the study's main authors. "This could open up new ways to treat obesity."

Previous studies have shown that lipid turnover may be accelerated simply by exercising more. This new research supports that idea 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, senior researcher at the Department of Cell and Molecular Biology at Karolinska Institute and 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."