A person of normal body weight who has excess belly fat is more likely to die prematurely than an obese person with a fair spread of fat around the body, researchers from the Mayo Clinic, Rochester, Minn. explained at the European Society of Cardiology Congress 2012 in Munich, Germany. Dr. Francisco Lopez-Jimenez said that people with a high waist-to-hip ratio, i.e. those with big bellies, but whose BMI (body mass index) are of normal weight, are more likely to die from a cardiovascular event or any cause than anybody else.

The researchers explained that health care professionals have always known that having central obesity - big bellies - is bad for the health. However, nobody was sure what effect having a large stomach might have on people whose body weight is normal for their height and age.

Several studies this year have shown that smaller waist sizes are linked to better health. Researchers from Cass Business School, City University, London, UK, revealed that if your waist is less than half your height, you will probably live longer.

Dr. Lopes-Jimenez said:

"We knew from previous research that central obesity is bad, but what is new in this research is that the distribution of the fat is very important even in people with a normal weight. This group has the highest death rate, even higher than those who are considered obese based on body mass index. From a public health perspective, this is a significant finding."

Scientists from Imperial College London and the German Institute of Human Nutrition showed that large waists almost double premature death risk.

Dr. Lopes-Jimenez and team gathered and analyzed data on 12,785 adults from a representative sample of the American population; the Third National Health and Nutrition Examination Survey. Their average age was 44 years and 47.4% of them were men.

This database had details on each individual's hip measurement, waist size, height, weight, socioeconomic status, illnesses, etc. They matched baseline data with the National Death Index to make calculations on lifespans and reasons for early death.

By using BMI (body mass index) details, they divided the people into three categories: normal, overweight and obese. They divided waist-to-hip ratios into normal and high. They took into account factors which might affect their results, such as baseline BMI, dyslipidemia, diabetes, high blood pressure, smoking, race, sex and age. They did not include people with COPD (chronic obstructive pulmonary disease) or cancer.

Over a follow-up period of 14.3 years, there were 2,562 deaths - 1,138 of them as a result of a cardiovascular problem.

The researchers found that people of normal weight with central obesity:
  • were 2.75 times more likely to have a cardiovascular death, than normal weight people without central obesity
  • were 2.08 times more likely to die from any cause, than normal weight people without central obesity
Karine Sahakyan, M.D., Ph.D., who was also involved in the study, said:

"The high risk of death may be related to a higher visceral fat accumulation in this group, which is associated with insulin resistance and other risk factors, the limited amount of fat located on the hips and legs, which is fat with presumed protective effects, and to the relatively limited amount of muscle mass."

Dr. Lopez-Jimenez explained that it is important for people to know that a normal BMI does not necessarily mean that your risk of heart disease is low. What matters is where the fat is. This can be better determined if you work out your waist-to-hip ratio, even if your body weight is normal for your height and age, he added.

A report by English health charity, Nuffield Health, revealed that larger waist sizes in women not only increased their risk of cardiovascular diseases, but also cancer.

What is waist-to-hip ratio?

Your waist-to-hip ratio is the measurement of your waist divided by the measurement of your hips. The waist is measured just above the navel (belly button), and the hips at their widest point.

A woman with a 28-inch waist and 36-inch hips will have a WHR (waist-to-hip ratio) of 28 divided by 36 = 0.77. Below are examples of male and female WHRs and how they might affect their health.

Female WHR
  • Less than 0.8 - low risk of cardiovascular health problems
  • 0.8 to 0.89 - moderate risk of cardiovascular health problems
  • 0.9 or over - high risk of cardiovascular problems
Male WHR
  • Less than 0.9 - low risk of cardiovascular health problems
  • 0.9 to 0.99 - moderate risk of cardiovascular health problems
  • 1 or over - high risk of cardiovascular problems
Experts say that if BMI as a predictor of cardiovascular related deaths were replaced by WHR, many more people would be included in the high-risk group.

Written by Christian Nordqvist