Too Much Belly Fat, Apple-shaped Bodies Increase Diabetes Risk

Everyone has some fat in one or another part of their body such as right under the skin or deeper inside, around your middle or heart, lungs, liver, and other organs. While having some body fat is normal, having too much belly fat can be dangerous for our health.

Besides causing obesity, belly fat is known to increase one’s odds of getting high blood pressure, type 2 diabetes, cardiovascular disease and certain cancers, including colon cancer and breast cancer.

Now a new large study has come up with fresh evidence revealing a causal association between abdominal fat and development of heart disease and diabetes.

According to the randomized study, a genetic predisposition to higher abdominal adiposity (fat), also known as an apple-shaped body (which describes a wider waistline), was causally linked to an elevated risk for coronary heart disease (CHD) and type 2 diabetes.

The study of more than 400,000 people claims to provide the strongest evidence so far suggesting that belly fat is directly linked to the development of chronic diseases.

“Individuals with abdominal adiposity have previously been observed to have higher rates of development of coronary heart disease and type 2 diabetes,” said lead author Connor Emdin, PhD, a researcher at the Broad Institute of MIT and Harvard. “However, it was unclear if abdominal adiposity causes heart disease and diabetes or if individuals with abdominal adiposity had heart disease and diabetes for other reasons. We were therefore surprised to see a relatively large effect of abdominal adiposity on risk of coronary heart disease and type 2 diabetes.”

To investigate, Emdin and colleagues analyzed genomic data and medical records from past studies including a total of 322,154 participants, as well as data from UK Biobank including up to 111,986people. They found a strong relationship between the genetic predisposition to higher waist-to-hip ratio (a measure of abdominal obesity) adjusted for BMI and cardiometabolic quantitative traits, i.e. lipids, insulin, glucose, and systolic blood pressure as well as type 2 diabetes and CHD.

More precisely, individuals who carried combinations of genes that predisposed them to higher waist-to-hip ratios were 77 percent more likely to have diabetes, and 46 percent more likely to have CHD, compared to those who weren’t predisposed. In addition, their likelihood of having risk factors for these medical conditions, including high cholesterol, high blood pressure, and high blood glucose levels, had increased significantly.

“These results permit several conclusions. First, these findings lend human genetic support to previous observations associating abdominal adiposity with cardiometabolic disease,” the authors write in a study paper.

“Second, these results suggest that body fat distribution, beyond simple measurement of BMI, could explain part of the variation in risk of type 2 diabetes and CHD noted across individuals and subpopulations. … Third, waist-to-hip ratio adjusted for BMI might prove useful as a biomarker for the development of therapies to prevent type 2 diabetes and CHD.”

The study paper appears in the February 14 issue of JAMA (Journal of the American Medical Association).