For years we've been hearing about the health risks associated with obesity. As your body mass index rises, so does your risk for coronary heart disease. Obesity also can lead to stroke, diabetes and high blood pressure.
But now a new study is sending a message that at first may seem a bit topsy-turvy: that middle-aged people with a body mass index (BMI) in the category of slightly overweight have higher chances of living longer than any other weight category.
BMI is a number derived from a person's weight and height that's used to calculate body fatness.
The nationwide study of nearly 10,000 people found that those who were slightly overweight in their 50s but kept their weight relatively stable were the most likely to survive over the next 16 years. They had better survival rates than even normal-weight people whose weight increased slightly, but stayed within the normal range. On the other hand, those who started out as very obese in their 50s and whose weight continued to increase were the most likely to die during that period.
Overall, the results suggest that about 7.2 percent of deaths after the age of 51 are due to weight gain among obese people, at least among the generation in this study, said Hui Zheng, lead author of the study and assistant professor of sociology at The Ohio State University, in a press release.
"You can learn more about older people's mortality risk by looking at how their weight is changing than you can by just looking at how much they weigh at any one time," Zheng added.
Zheng emphasized that the study's results applied only to those over 50. Previous research, he noted, suggests that being overweight may not be helpful for younger people.
"Our other research suggests that the negative effect of obesity on health is greater for young people than it is for older people, so young people especially shouldn't think that being overweight is harmless," he said.
So who is being slightly overweight beneficial for older people?
"It is probably because the older population is more likely to get illnesses and disease, especially cancer, that cause dangerous weight loss," Zheng said. "In that case, a small amount of extra weight may provide protection against nutritional and energy deficiencies, metabolic stresses, the development of wasting and frailty, and loss of muscle and bone density caused by chronic diseases."
Younger people are less likely to get many of the diseases that afflict older adults, which is one reason extra weight is not good for them, he said.
But Zheng said the main takeaway for everyone, including older adults, is that packing on the pounds, especially if you're obese, can be hazardous to your health.
"Continuing to put on weight can lower your life expectancy," he said.
This new study was published online this month in the American Journal of Epidemiology.
In an analysis of 97 studies released earlier this summer, researchers from the Centers for Disease Control and Prevention (CDC) found that being overweight actually lowered a person's risk of dying from any cause by 6 percent.
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