A widening waistline can harm the health of older women, even if they avoid obesity, new research suggests.
It's a condition known as "central obesity" – a concentration of fat around the abdomen. Central obesity can occur even if it's not enough to shift a person's body mass index (BMI) into the obese range, explained researchers led by Wei Bao, a professor of epidemiology at the University of Iowa.
Body shape also important
His study found that a large waist size – about 35 inches (88.9cm) or more – significantly increased the risk of an early death for women over 49, even when they had a normal BMI.
The study findings suggest that doctors "look not only at body weight but also body shape when assessing a patient's health risks," Bao concluded in a university news release.
One expert who reviewed the new study agreed.
"How does measuring waist circumference help us understand body composition? A higher waist circumference assumes an accumulation of fat in the abdominal region," explained Ashley Baumohl, a clinical dietitian at Lenox Hill Hospital in New York City.
"So for those that have a normal BMI but a larger waist circumference, we can assume that a higher percentage of that weight is coming from fat rather than muscle," she added. And all that fat can take a toll on health.
In the new study, Bao's group tracked data from more than 156 000 US women, aged 50 to 79, whose health was tracked from 1993 to 2017 as part of a large national study.
Heart disease and cancer
Women who were considered to have normal BMI but had a large waist size had a 31% higher risk of dying during the study period, compared to those with a normal BMI but a smaller waist.
That hike in risk is comparable to the 30% increased odds for death observed among obese people with central obesity, who were in the highest risk group, the researchers said.
The two main causes of death in people with normal BMI but large waist size were heart disease and obesity-related cancers, according to the report published online in JAMA Network Open.
Right now, clinical guidelines say doctors need rely only on a person's BMI to determine their obesity-related health risk, Bao noted. So people who are in a high-risk group because of other risk factors, such as percentage of body fat, might still believe they're "healthy".
Another expert, Dr Guy Mintz, said, "This study serves as a wake-up call to physicians to not be satisfied with just a BMI, but to look at fat distribution and waist circumference." In doing so, doctors can spot "a group of patients that might be otherwise overlooked", he noted.
And, "once central obesity is identified, patient education is essential to change diet, exercise and flatten our abdomens," said Mintz, who directs cardiovascular health at Northwell Health's Sandra Atlas Bass Heart Hospital in Manhasset, New York.
Mintz added that, "while the article looked at an older female population, I personally feel it holds true in younger patients as well".
How could the accumulation of fat around the tummy increase early death risk? According to Mintz, this type of "visceral" fat is closely tied to chronic inflammation, the excess production of insulin, and insulin resistance – a precursor to diabetes. Together, those three factors can trigger diabetes, hardening of the arteries and heart disease, he explained.
These states can be turned around, however. Weight reduction is crucial, Baumohl said, even if it's not always easy.
"It is important to point out that we as humans cannot target specific areas of our body to lose weight from; a phenomenon commonly referred to as 'spot reduction'," she said.
"There are hundreds of fad diets out there promising quick and easy tricks to get that flat stomach and to lose those love handles," Baumohl said. However, "at this time, the only prescription for losing weight, no matter where on the body, is nutrition education, a supportive environment and personal motivation."
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