FRIDAY, Oct. 14 (HealthDay News) -- The skeletal muscle of severely obese people is specially programmed to amass fat, researchers report.

The finding suggests the muscle has a metabolic "memory" of obesity, and it may explain why obese people have such a hard time losing weight, even when they cut calories.

The study in the October issue of Cell Metabolism also suggests that exercise may be able to override this programming and improve the ability of the obese to shed unwanted pounds.

Researchers found that the fat-building enzyme stearoyl-CoA desaturase-1 (SCD-1) is three times more abundant in the muscle of obese people than the muscle of lean people. This finding provides insight into an important link between obesity, diabetes and abnormal fat buildup in muscle, the researchers said.

"Obesity and type 2 diabetes are strongly associated with abnormal lipid metabolism and the accumulation of fat droplets in muscle, but the underlying cause of these perturbations have been unknown," study author Deborah Muoio, of the Sarah W. Stedman Nutrition and Metabolism Center at Duke University Medical Center, said in a prepared statement.

"We've now shown that SCD-1 is at least a very important contributor to changes in lipid handling within muscle and the progression of obesity," she said.

She and her colleagues plan to examine whether increased physical activity can reverse levels of SCD-1 or help neutralize its effects. It's known that exercise produces changes in muscle metabolism.