But it found that every extra 4 inches (10cm) of waist size was associated with an 11% higher chance of dying prematurely.
However, many believe waist circumference is an indicator of obesity and risk for illnesses, such as type-2 diabetes and heart disease.
The new ground-breaking study was recently published in the British Medical Journal.
Tauseef Ahmad Khan was the study author from the department of nutritional sciences at the University of Toronto in Canada.
Dr Khan said: "People should be more concerned about their waist rather than focusing only on weight or BMI.
"Waist is a better indicator of belly fat and while one cannot target where one loses fat from, losing weight through diet and exercise will also reduce waist and therefore belly fat.
"Belly fat is the fat that is stored around the organs in the abdomen and its excess is linked to high cholesterol, high blood pressure, heart disease, diabetes, and stroke.
"Therefore, having more belly fat can increase the risk of dying from these diseases."
The researchers found that most measures of abdominal fat were "significantly and positively associated with a higher all-cause morality risk" even after BMI was taken into account.
They said: "We found that the associations remained significant after body mass index was accounted for, which indicated that abdominal deposition of fat, independent of overall obesity, is associated with a higher risk."
Their findings suggest that thigh and hip circumference were "inversely associated with all-cause morality risk".
Each 10cm increase in hip circumference was associated with a 10% lower risk of death from all causes.
Meanwhile, Dr Khan says hip fat is considered beneficial and thigh size is an indicator of the amount of muscle.
The risks of belly fat were the same when accounting for BMI, suggesting it increases a person's chance of death regardless of their weight.
More than 70 studies, which followed more than 2.5 million people between three and 24 years, were analysed by the researchers.
According to the NHS, regardless of height or BMI, men should try to lose weight if their waist is above 37in (94cm), while for women it's above 31.5in (80cm).
