[Greey]

Overweight and obese people get less out of resistance training than leaner people do, researchers said on Friday in a study that suggests the overweight may have to try harder to get results.

But it does not mean they should give up, said the researchers, who noted the differences were small.

"People who are overweight and obese experience numerous health benefits from exercise training programs even in the absence of significant amounts of weight loss or improvements in cardiopulmonary physical fitness," Linda Pescatello of the University of Connecticut and colleagues wrote in their report, published in the Journal of Strength and Conditioning Research.

They tested 687 adults aged 18 to 39, measuring their body fat and using magnetic resonance imaging to look at their muscles and fat.

The volunteers did 12 weeks of 45- to 60-minute workouts of their upper arms, working the biceps and triceps.

Everyone gained strength and muscle. But the overweight and obese volunteers gained 4 percent to 17 percent less than those of normal weight.

Differences could be genetic, the researchers said.

"People with overweight and obesity have alterations in skeletal muscle structure and function compared to those who are normal weight that could also contribute to variability in the exercise response," they wrote.