The U.S. researchers say men and women who are fit have a lower mortality risk than those of normal weight but low fitness levels.
These conclusions come as a result of a study by researchers at the University of South Carolina who tracked about 2,603 people age 60 plus in order to examine how physical fitness and body fat affected their death rates over a 12 year period; over the study period there were 450 deaths.
The groups fitness was assessed by a treadmill test, and their weight by body mass index (BMI) which is calculated from a person's weight and height as well as waist circumference and body fat percentage.
Physical education specialist Steven Blair and his colleagues found that those in the group who were overweight or obese had a lower mortality risk than those of normal weight but low fitness levels.
The researchers say those in the lowest fifth in terms of fitness had a death rate four times higher than participants ranked in the top fifth for fitness and indicates that being fit provides protection against mortality in men and women 60 and older, whether they're normal weight, overweight or obese.
The findings come at a time when obesity has become a serious issue worldwide and an increasing number of people are obese and living sedentary lifestyles and of course populations are aging.
The researchers do not deny there is an obesity epidemic but say all too often the focus is almost exclusively on obesity, and exercise and fitness are ignored.
The study demonstrates that even a modest effort to improve physical activity can provide health benefits say the researchers.
Dr. Xuemei Sui one of the study authors says people who are overweight or obese need not fear physical activity and dismiss it and drastic steps may not be needed.
Blair says even those who are overweight or obese, sedentary and unfit, can begin by taking three 10-minute walks a day for at least five days a week; they may not lose an enormous amount of weight he says, but they will be much healthier.
Blair also recommends a healthy diet including lots of fruit, vegetables and whole grains.
Previous studies have also provided evidence that obesity and physical inactivity each can produce a higher risk of death in middle-aged adults.
According to the U.S. Centers for Disease Control and Prevention (CDC) more than a third of U.S. adults are obese and the case is much the same in Britain, Australia and other developed countries.
Expert say obesity is a major risk factor for cardiovascular disease, certain types of cancer and diabetes and is implicated in many other illnesses.
The CDC says 50% of adults do not do enough regular physical exercise which reduces the risks of dying of coronary heart disease, as well as lowering the risk for stroke, colon cancer, diabetes and high blood pressure.
The researchers say the study provide further evidence regarding the complex long-term relationship between fitness, body size, and survival.
They suggest it may be possible to reduce all-cause death rates among older adults, including those who are obese, by promoting regular physical activity, such as brisk walking for 30 minutes or more on most days of the week.
This would keep most individuals out of the low-fitness category and also enable them to achieve a healthy lifestyle and enjoy a longer life in better health.
The study is published in the Journal of the American Medical Association.