It's time to take out the measuring tape.
A new study is adding to the growing evidence that waist circumference – not just body mass index (BMI) – is a key predictor for heart disease, cancer, respiratory problems and premature death.
The study, conducted by researchers at the Mayo Clinic and published in this month's Mayo Clinic Proceedings, found that people who have large waist circumferences are more likely to die younger and suffer a host of health-related problems than their peers with smaller waists.
The results are consistent in all people, including those that have "normal" BMIs, the study found.
The findings are significant because they reflect a shift away from the fixation solely on BMI as a predictor of future health. (BMI uses a person's weight and height to come up with a number that can be used to indicate how much fat he or she is carrying.)
"Carrying a large belly even in the normal weight range has health implications," said Dr. James Cerhan, lead author of the study and professor of epidemiology at the Mayo Clinic in Rochester, Minn.
Instead, many researchers are drawing attention to abdominal fat as the issue more people should be focusing on, rather than their total weight alone. Abdominal fat is considered dangerous because it gets stored near internal organs, where it can cause major disruptions and lead to a marked increase in disease risk. Cerhan described it as "metabolically active" fat that can interfere with a number of important processes, such as glucose control.
A person's BMI may still be able to give them important information about their body weight. But many health experts say it can also be a flawed model that doesn't give people the full picture of their health.
What that basically means is a person may look relatively slim and could have a normal BMI. But if they are carrying extra weight in their abdomen, they are also at an increased risk for premature death, heart disease, stroke and other conditions.
The Heart and Stroke Foundation provides an online tool that people can use to measure their waist circumference and determine if they are at risk. The foundation says that for people of Caucasian, sub-Saharan African, Eastern Mediterranean and Middle Eastern descent, a healthy circumference is below 102 centimetres (40 inches) for men and 88 cm (35 inches) for women. For South Asian, Malaysian, Asian, Chinese, Japanese and ethnic South and Central Americans, the cutoff is 90 cm (35 inches) for men and 80 cm (32 inches) for women.
In the new study, researchers looked at data from 11 different studies that included more than 600,000 people around the world. They found that men who had waists that were 109 cm (43 inches) or larger had twice the mortality risk than men with waists smaller than 89 cm (35 inches).
For men with larger waists, this translated to a life expectancy that was three years shorter than their peers after age 40.
Women with a waist circumference of 94 cm (37 inches) had an 80 per cent higher mortality risk than those with waists that were 69 cm (27 inches) or less. For women with larger waists, that translates to a life expectancy five years shorter after age 40.
Cerhan noted that sit-ups won't help people lose abdominal fat. The key is to increase the amount of physical activity to shed those pounds.