Obese and overweight people can live as long as those with a normal weight. The question is, how disabled will they be?
Published 06/12/2007
There's some good news and some not so good news for the overweight and obese.
First the good news. Obese people are likely to live as long as people of normal weight – as long as they're fit. That's the finding of US researchers who studied 2, 603 people in their sixties and older over a 12-year period.
Participants were measured for body weight, waist size and body mass index. (Body mass index, or BMI, is a figure calculated by dividing weight in kg by height in metres squared. Normal is 20 to 25; over 30 indicates obesity.) Each person had a battery of medical tests. They also underwent treadmill exercise testing to see how fit they were.
It turned out that those who were most fit were much less likely to have diabetes, high cholesterol, and high blood pressure. And they were much more likely to be alive at the end of the study. Death rates for those at the highest fitness levels were less than half that of those at the lowest fitness levels.
But here's the interesting finding: among people who were fit, survival rates were similar for normal weight, overweight, and obese people.
In other words, a person's weight didn't affect their survival rates, but fitness levels did. The conclusion: if a person is overweight, they'll live as long as anyone else with a normal weight, as long as they're fit.
Older, but disabled
Now for the not-so-good news. Other researchers from the University of Pennsylvania, Philadelphia, agree that obese people can live as long as people with a normal weight. They say that survival rates for obese people have increased markedly since the 1960s, which they put down to better medical treatments for the conditions associated with it. The problem is, there's a greater chance they'll be living with disabilities than people of normal weight.
The researchers looked at 10, 000 people of various weight levels – some obese, some not. They measured their BMI, and also measured how well the subjects could cope with tasks of life – things like how well they could walk a quarter of a mile, walk up 10 steps, lift 10 weights, walk between rooms, and whether they had trouble moving from one place to another, eating, and dressing.
Once a person's BMI got over about 30, they experienced a big jump in difficulties with these everyday tasks. For example, those with a BMI over 40 had between five and nine times the disability of those with a normal weight.
The disabilities were due to reduced mobility from a greater body mass, and from some of the conditions associated with obesity – things like musculoskeletal disorders (arthritis, back pain), reduced muscle strength and reduced heart and lung function.
So yes, obese people are living longer, but their lives are still being affected by the disabilities associated with the condition, the researchers concluded.
What it means is that the focus for someone who's overweight should be not just on living longer, but reducing the risk of disability in those later years.
As the first study showed, some of the medical complications of obesity can be managed by keeping fit. Eating a healthy diet and having regular checks-ups with a doctor and any chronic medical conditions treated, will help.
Reducing the disability from larger than normal body mass requires not just fitness, but shedding body weight. That requires not just exercise but caloric restriction – a weight loss diet.
Interestingly, in the second study, disability became significant over a BMI of about 30, suggesting that obese people should aim to get below 30, and ideally even lower if possible.
