Mid-life obesity may be triggered by enzyme, not poor lifestyle choices and lack of will power, study on mice shows

US researchers have identified an enzyme that may play a central role in the development of obesity in mid life.

In two groups of mice being fed high-fat foods, those who received an inhibitor that blocked the enzyme had a 40 per cent decrease in weight gain compared with those that did not receive the drug. The findings, published in the US journal Cell Metabolism, could upend current notions about why people gain weight as they age, and could one day lead to more effective weight-loss medications.

“Our society attributes the weight gain and lack of exercise at mid life (approximately 30 to 60 years) primarily to poor lifestyle choices and lack of will power, but this study shows that there is a genetic programme driven by an overactive enzyme that promotes weight gain and loss of exercise capacity at mid life,” said lead study author Jay Chung, head of the Laboratory of Obesity and Aging Research at the National Heart, Lung, and Blood Institute (NHLBI), part of the US National Institutes of Health.

Researchers have known for years that losing weight and maintaining the capacity to exercise tend to get harder beginning between ages 30 to 40 – the start of mid life. Scientists have developed new therapies for obesity, including fat-fighting pills, but many of those therapies have failed.

Chung and his associates searched for biochemical changes that occurred in middle-aged animals that are equivalent to 45 years in humans. They found that an enzyme called DNA-dependent protein kinase, or DNA-PK, increases in activity with age. In the meantime, the researchers said, middle-aged people who are fighting obesity should not abandon common practices of reducing calorie intake and boosting exercise, even if it takes a while to see results. Xinhua