Heavy seniors who want to lose extra kilos safely shouldn't skip the weight machines or the treadmill, research suggests.
Experts have worried about recommending weight loss to older, obese people because it speeds up bone and muscle loss, increasing the danger of falls and broken bones.
But a study published by the New England Journal of Medicine suggests a combination of exercises is the safest approach.
Losing weight plus aerobic activity and strength training improved people's health more than dieting plus either type of exercise alone.
It may have big implications for helping people continue to live independently as they age.
"It is the worst of both worlds, being fat and frail," said Dr Dennis Villareal of Baylor College of Medicine in Houston, who led the study.
"It's never too late to change lifelong unhealthy habits."
The study involved 141 older obese people considered frail who were randomly assigned to a diet program and told to exercise three times a week.
One group did aerobics such as treadmill walking. Another did strength training with weight machines. A third group did aerobics and strength training.
After six months, all the groups - except a control do-nothing group - had lost weight, about 19 pounds (nine kilograms) on average.
The combination and aerobics-only groups built their ability to use oxygen most efficiently, which can increase endurance.
The combination and strength-only groups preserved the most lean mass and bone.
The health differences showed up in follow-up testing where participants did a series of nine tasks including picking up a penny, standing up from a chair and climbing stairs.
Most improved was the combination group with a 21 per cent average increase.
Minor injuries such as knee pain and shoulder pain among the exercisers were not enough to outweigh the benefits, Dr Villareal said.
The study excluded people with severe heart disease and other serious health problems, so the results apply only to people well enough to start an exercise program.
